text: /*--------------------------------------------------------------------
   * guc.c
   *
   * Support for grand unified configuration scheme, including SET
   * command, configuration file, and command line options.
   * See src/backend/utils/misc/README for more information.
   *
   *
   * Portions Copyright (c) 2005-2010, Greenplum inc
   * Copyright (c) 2000-2009, PostgreSQL Global Development Group
   * Written by Peter Eisentraut <peter_e@gmx.net>.
   *
   * IDENTIFICATION
   *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.563 2010/07/20 00:34:44 rhaas Exp $
   *
   *--------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include <ctype.h>
  #include <float.h>
  #include <limits.h>
  #include <unistd.h>
  #include <sys/stat.h>
  #ifdef HAVE_SYSLOG
  #include <syslog.h>
  #endif
  
  #include "access/gin.h"
  #include "access/transam.h"
  #include "access/twophase.h"
  #include "access/xact.h"
  #include "catalog/namespace.h"
  #include "commands/async.h"
  #include "commands/prepare.h"
  #include "commands/vacuum.h"
  #include "commands/variable.h"
  #include "commands/trigger.h"
  #include "funcapi.h"
  #include "libpq/auth.h"
  #include "libpq/pqformat.h"
  #include "miscadmin.h"
  #include "optimizer/cost.h"
  #include "optimizer/paths.h"
  #include "optimizer/planmain.h"
  #include "parser/gramparse.h"
  #include "parser/parse_expr.h"
  #include "parser/parse_relation.h"
  #include "parser/parse_type.h"
  #include "parser/scansup.h"
  #include "pgstat.h"
  #include "postmaster/autovacuum.h"
  #include "postmaster/bgwriter.h"
  #include "postmaster/postmaster.h"
  #include "postmaster/syslogger.h"
  #include "replication/walsender.h"
  #include "replication/walreceiver.h"
  #include "postmaster/walwriter.h"
  #include "storage/fd.h"
  #include "storage/freespace.h"
  #include "tcop/tcopprot.h"
  #include "tsearch/ts_cache.h"
  #include "utils/builtins.h"
  #include "utils/guc_tables.h"
  #include "utils/memutils.h"
  #include "utils/pg_locale.h"
  #include "utils/plancache.h"
  #include "utils/portal.h"
  #include "utils/ps_status.h"
  #include "utils/tzparser.h"
  #include "utils/xml.h"
  #include "cdb/cdbdisp_query.h"
  #include "cdb/cdbvars.h"
  
  #ifdef USE_SSL
  #include <openssl/crypto.h>
  #include <openssl/err.h>
  #endif
  
  #ifndef PG_KRB_SRVTAB
  #define PG_KRB_SRVTAB ""
  #endif
  #ifndef PG_KRB_SRVNAM
  #define PG_KRB_SRVNAM ""
  #endif
  
  #define CONFIG_FILENAME "postgresql.conf"
  #define HBA_FILENAME	"pg_hba.conf"
  #define IDENT_FILENAME	"pg_ident.conf"
  
  #ifdef EXEC_BACKEND
  #define CONFIG_EXEC_PARAMS "global/config_exec_params"
  #define CONFIG_EXEC_PARAMS_NEW "global/config_exec_params.new"
  #endif
  
  #define KB_PER_MB (1024)
  #define KB_PER_GB (1024*1024)
  
  #define MS_PER_S 1000
  #define S_PER_MIN 60
  #define MS_PER_MIN (1000 * 60)
  #define MIN_PER_H 60
  #define S_PER_H (60 * 60)
  #define MS_PER_H (1000 * 60 * 60)
  #define MIN_PER_D (60 * 24)
  #define S_PER_D (60 * 60 * 24)
  #define MS_PER_D (1000 * 60 * 60 * 24)
  
  /* XXX these should appear in other modules' header files */
  extern bool Log_disconnections;
  extern int	CommitDelay;
  extern int	CommitSiblings;
  extern char *default_tablespace;
  extern char *temp_tablespaces;
  extern bool synchronize_seqscans;
  extern bool fullPageWrites;
  extern int	ssl_renegotiation_limit;
  
  #ifdef USE_SSL
  extern char *SSLCipherSuites;
  #endif
  #ifdef TRACE_SYNCSCAN
  extern bool trace_syncscan;
  #endif
  #ifdef DEBUG_BOUNDED_SORT
  extern bool optimize_bounded_sort;
  #endif
  
  #ifdef USE_SSL
  extern char *SSLCipherSuites;
  #endif
  
  
  static const char *assign_log_destination(const char *value,
  					   bool doit, GucSource source);
  
  #ifdef HAVE_SYSLOG
  static int	syslog_facility = LOG_LOCAL0;
  
  static const char *assign_syslog_facility(const char *facility,
  					   bool doit, GucSource source);
  static const char *assign_syslog_ident(const char *ident,
  					bool doit, GucSource source);
  #endif
  
  static const char *assign_defaultxactisolevel(const char *newval, bool doit,
  						   GucSource source);
  static const char *assign_session_replication_role(const char *newval, bool doit,
  								GucSource source);
  static const char *assign_log_min_messages(const char *newval, bool doit,
  						GucSource source);
  static const char *assign_client_min_messages(const char *newval,
  						   bool doit, GucSource source);
  static const char *assign_min_error_statement(const char *newval, bool doit,
  						   GucSource source);
  static const char *assign_IntervalStyle(const char *newval, bool doit,
  						   GucSource source);
  static const char *assign_log_error_verbosity(const char *newval, bool doit,
  						   GucSource source);
  static const char *assign_log_statement(const char *newval, bool doit,
  					 GucSource source);
  static const char *show_num_temp_buffers(void);
  static bool assign_phony_autocommit(bool newval, bool doit, GucSource source);
  static const char *assign_custom_variable_classes(const char *newval, bool doit,
  							   GucSource source);
  static bool assign_debug_assertions(bool newval, bool doit, GucSource source);
  static bool assign_ssl(bool newval, bool doit, GucSource source);
  static bool assign_stage_log_stats(bool newval, bool doit, GucSource source);
  static bool assign_log_stats(bool newval, bool doit, GucSource source);
  static bool assign_transaction_read_only(bool newval, bool doit, GucSource source);
  static const char *assign_canonical_path(const char *newval, bool doit, GucSource source);
  static const char *assign_backslash_quote(const char *newval, bool doit, GucSource source);
  static const char *assign_timezone_abbreviations(const char *newval, bool doit, GucSource source);
  static const char *assign_xmlbinary(const char *newval, bool doit, GucSource source);
  static const char *assign_xmloption(const char *newval, bool doit, GucSource source);
  static const char *show_archive_command(void);
  static bool assign_tcp_keepalives_idle(int newval, bool doit, GucSource source);
  static bool assign_tcp_keepalives_interval(int newval, bool doit, GucSource source);
  static bool assign_tcp_keepalives_count(int newval, bool doit, GucSource source);
  static const char *assign_pgstat_temp_directory(const char *newval, bool doit, GucSource source);
  static const char *show_IntervalStyle(void);
  static const char *show_tcp_keepalives_idle(void);
  static const char *show_tcp_keepalives_interval(void);
  static const char *show_tcp_keepalives_count(void);
  static bool assign_autovacuum_max_workers(int newval, bool doit, GucSource source);
  static bool assign_maxconnections(int newval, bool doit, GucSource source);
  
  static const char *assign_application_name(const char *newval, bool doit, GucSource source);
  
  static int	defunct_int = 0;
  static bool	defunct_bool = false;
  static double defunct_double = 0;
  
  /*
   * GUC option variables that are exported from this module
   */
  #ifdef USE_ASSERT_CHECKING
  bool		assert_enabled = true;
  #else
  bool		assert_enabled = false;
  #endif
  bool		log_duration = false;
  bool		Debug_print_plan = false;
  bool		Debug_print_parse = false;
  bool		Debug_print_rewritten = false;
  bool		Debug_pretty_print = false;
  bool		Explain_pretty_print = true;
  
  bool		log_parser_stats = false;
  bool		log_planner_stats = false;
  bool		log_executor_stats = false;
  bool		log_statement_stats = false;		/* this is sort of all three
  												 * above together */
  bool		log_btree_build_stats = false;
  
  bool		check_function_bodies = true;
  bool		default_with_oids = false;
  bool		SQL_inheritance = true;
  
  bool		Password_encryption = true;
  
  int			log_min_error_statement = ERROR;
  int			log_min_messages = WARNING;
  int			client_min_messages = NOTICE;
  int			log_min_duration_statement = -1;
  int			log_temp_files = -1;
  
  int			num_temp_buffers = 1000;
  
  char	   *ConfigFileName;
  char	   *HbaFileName;
  char	   *IdentFileName;
  char	   *external_pid_file;
  
  char	   *pgstat_temp_directory;
  
  char	   *application_name;
  
  int			tcp_keepalives_idle;
  int			tcp_keepalives_interval;
  int			tcp_keepalives_count;
  
  /*
   * These variables are all dummies that don't do anything, except in some
   * cases provide the value for SHOW to display.  The real state is elsewhere
   * and is kept in sync by assign_hooks.
   */
  static char *client_min_messages_str;
  static char *log_min_messages_str;
  static char *log_error_verbosity_str;
  static char *log_statement_str;
  static char *log_min_error_statement_str;
  static char *log_destination_string;
  
  #ifdef HAVE_SYSLOG
  static char *syslog_facility_str;
  static char *syslog_ident_str;
  #endif
  static bool phony_autocommit;
  static bool session_auth_is_superuser;
  static double phony_random_seed;
  static char *backslash_quote_string;
  static char *client_encoding_string;
  static char *IntervalStyle_string;
  static char *datestyle_string;
  static char *default_iso_level_string;
  static char *session_replication_role_string;
  static char *locale_ctype;
  static char *regex_flavor_string;
  static char *server_encoding_string;
  static char *server_version_string;
  static int	server_version_num;
  static char *timezone_string;
  static char *log_timezone_string;
  static char *timezone_abbreviations_string;
  static char *XactIsoLevel_string;
  static char *custom_variable_classes;
  static char *xmlbinary_string;
  static char *xmloption_string;
  static int	max_function_args;
  static int	max_index_keys;
  static int	max_identifier_length;
  static int	block_size;
  static bool integer_datetimes;
  //static bool standard_conforming_strings;
  static char *allow_system_table_mods_str;
  
  /* should be static, but commands/variable.c needs to get at these */
  char	   *role_string;
  char	   *session_authorization_string;
  
  static const char *
  assign_allow_system_table_mods(const char *newval,
  							   bool doit,
  							   GucSource source);
  
  static const char *
  show_allow_system_table_mods(void);
  
  
  /*
   * Displayable names for context types (enum GucContext)
   *
   * Note: these strings are deliberately not localized.
   */
  const char *const GucContext_Names[] =
  {
  	 /* PGC_INTERNAL */ "internal",
  	 /* PGC_POSTMASTER */ "postmaster",
  	 /* PGC_SIGHUP */ "sighup",
  	 /* PGC_BACKEND */ "backend",
  	 /* PGC_SUSET */ "superuser",
  	 /* PGC_USERSET */ "user"
  };
  
  /*
   * Displayable names for source types (enum GucSource)
   *
   * Note: these strings are deliberately not localized.
   */
  const char *const GucSource_Names[] =
  {
  	 /* PGC_S_DEFAULT */ "default",
  	 /* PGC_S_ENV_VAR */ "environment variable",
  	 /* PGC_S_FILE */ "configuration file",
  	 /* PGC_S_ARGV */ "command line",
  	 /* PGC_S_DATABASE */ "database",
  	 /* PGC_S_USER */ "user",
  	 /* PGC_S_CLIENT */ "client",
  	 /* PGC_S_OVERRIDE */ "override",
  	 /* PGC_S_INTERACTIVE */ "interactive",
  	 /* PGC_S_TEST */ "test",
  	 /* PGC_S_SESSION */ "session"
  };
  
  /*
   * Displayable names for the groupings defined in enum config_group
   */
  const char *const config_group_names[] =
  {
  	/* UNGROUPED */
  	gettext_noop("Ungrouped"),
  	/* FILE_LOCATIONS */
  	gettext_noop("File Locations"),
  	/* CONN_AUTH */
  	gettext_noop("Connections and Authentication"),
  	/* CONN_AUTH_SETTINGS */
  	gettext_noop("Connections and Authentication / Connection Settings"),
  	/* CONN_AUTH_SECURITY */
  	gettext_noop("Connections and Authentication / Security and Authentication"),
  	/* EXTERNAL_TABLES */
  	gettext_noop("External Tables"),
  	/* APPENDONLY_TABLES */
  	gettext_noop("Append-Only Tables"),
  	/* RESOURCES */
  	gettext_noop("Resource Usage"),
  	/* RESOURCES_MEM */
  	gettext_noop("Resource Usage / Memory"),
  	/* RESOURCES_FSM */
  	gettext_noop("Resource Usage / Free Space Map"),
  	/* RESOURCES_KERNEL */
  	gettext_noop("Resource Usage / Kernel Resources"),
  	/* RESOURCES_MGM */
  	gettext_noop("Resource Usage / Resources Management"),
  	/* WAL */
  	gettext_noop("Write-Ahead Log"),
  	/* WAL_SETTINGS */
  	gettext_noop("Write-Ahead Log / Settings"),
  	/* WAL_CHECKPOINTS */
  	gettext_noop("Write-Ahead Log / Checkpoints"),
  	/* WAL based REPLICATION */
  	gettext_noop("WAL Replication"),
  	/* QUERY_TUNING */
  	gettext_noop("Query Tuning"),
  	/* QUERY_TUNING_METHOD */
  	gettext_noop("Query Tuning / Planner Method Configuration"),
  	/* QUERY_TUNING_COST */
  	gettext_noop("Query Tuning / Planner Cost Constants"),
  	/* QUERY_TUNING_OTHER */
  	gettext_noop("Query Tuning / Other Planner Options"),
  	/* LOGGING */
  	gettext_noop("Reporting and Logging"),
  	/* LOGGING_WHERE */
  	gettext_noop("Reporting and Logging / Where to Log"),
  	/* LOGGING_WHEN */
  	gettext_noop("Reporting and Logging / When to Log"),
  	/* LOGGING_WHAT */
  	gettext_noop("Reporting and Logging / What to Log"),
  	/* STATS */
  	gettext_noop("Statistics"),
  	/* STATS_ANALYZE */
  	gettext_noop("Statistics / ANALYZE Database Contents"),
  	/* STATS_MONITORING */
  	gettext_noop("Statistics / Monitoring"),
  	/* STATS_COLLECTOR */
  	gettext_noop("Statistics / Query and Index Statistics Collector"),
  	/* AUTOVACUUM */
  	gettext_noop("Autovacuum"),
  	/* CLIENT_CONN */
  	gettext_noop("Client Connection Defaults"),
  	/* CLIENT_CONN_STATEMENT */
  	gettext_noop("Client Connection Defaults / Statement Behavior"),
  	/* CLIENT_CONN_LOCALE */
  	gettext_noop("Client Connection Defaults / Locale and Formatting"),
  	/* CLIENT_CONN_OTHER */
  	gettext_noop("Client Connection Defaults / Other Defaults"),
  	/* LOCK_MANAGEMENT */
  	gettext_noop("Lock Management"),
  	/* COMPAT_OPTIONS */
  	gettext_noop("Version and Platform Compatibility"),
  	/* COMPAT_OPTIONS_PREVIOUS */
  	gettext_noop("Version and Platform Compatibility / Previous PostgreSQL Versions"),
  	/* COMPAT_OPTIONS_CLIENT */
  	gettext_noop("Version and Platform Compatibility / Other Platforms and Clients"),
      /* COMPAT_OPTIONS_IGNORED */
      gettext_noop("Version and Platform Compatibility / Ignored"),
      /* GP_ARRAY_CONFIGURATION */
      gettext_noop(PACKAGE_NAME " / Array Configuration"),
      /* GP_ARRAY_TUNING */
      gettext_noop(PACKAGE_NAME " / Array Tuning"),
      /* GP_WORKER_IDENTITY */
      gettext_noop(PACKAGE_NAME " / Worker Process Identity"),
  	/* GP_ERROR_HANDLING */
  	gettext_noop("GPDB Error Handling"),
  	/* PRESET_OPTIONS */
  	gettext_noop("Preset Options"),
  	/* CUSTOM_OPTIONS */
  	gettext_noop("Customized Options"),
  	/* DEVELOPER_OPTIONS */
  	gettext_noop("Developer Options"),
  
  	/* DEPRECATED_OPTIONS */
  	gettext_noop("Deprecated Options"),
  	/* DEFUNCT_OPTIONS */
  	gettext_noop("Defunct Options"),
  
  	/* help_config wants this array to be null-terminated */
  	NULL
  };
  
  /*
   * Displayable names for GUC variable types (enum config_type)
   *
   * Note: these strings are deliberately not localized.
   */
  const char *const config_type_names[] =
  {
  	 /* PGC_BOOL */ "bool",
  	 /* PGC_INT */ "integer",
  	 /* PGC_REAL */ "real",
  	 /* PGC_STRING */ "string"
  };
  
  
  /*
   * Contents of GUC tables
   *
   * See src/backend/utils/misc/README for design notes.
   *
   * TO ADD AN OPTION:
   *
   * 1. Declare a global variable of type bool, int, double, or char*
   *	  and make use of it.
   *
   * 2. Decide at what times it's safe to set the option. See guc.h for
   *	  details.
   *
   * 3. Decide on a name, a default value, upper and lower bounds (if
   *	  applicable), etc.
   *
   * 4. Add a record below.
   *
   * 5. Add it to src/backend/utils/misc/postgresql.conf.sample, if
   *	  appropriate.
   *
   * 6. Don't forget to document the option (at least in config.sgml).
   *
   * 7. If it's a new GUC_LIST option you must edit pg_dumpall.c to ensure
   *	  it is not single quoted at dump time.
   */
  
  
  /******** option records follow ********/
  
  static struct config_bool ConfigureNamesBool[] =
  {
  	{
  		{"enable_seqscan", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enables the planner's use of sequential-scan plans."),
  			NULL
  		},
  		&enable_seqscan,
  		true, NULL, NULL
  	},
  	{
  		{"enable_indexscan", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enables the planner's use of index-scan plans."),
  			NULL
  		},
  		&enable_indexscan,
  		true, NULL, NULL
  	},
  	{
  		{"enable_bitmapscan", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enables the planner's use of bitmap-scan plans."),
  			NULL
  		},
  		&enable_bitmapscan,
  		true, NULL, NULL
  	},
  	{
  		{"enable_tidscan", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enables the planner's use of TID scan plans."),
  			NULL
  		},
  		&enable_tidscan,
  		true, NULL, NULL
  	},
  	{
  		{"enable_sort", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enables the planner's use of explicit sort steps."),
  			NULL
  		},
  		&enable_sort,
  		true, NULL, NULL
  	},
  	{
  		{"enable_hashagg", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enables the planner's use of hashed aggregation plans."),
  			NULL
  		},
  		&enable_hashagg,
  		true, NULL, NULL
  	},
  	{
  		{"enable_nestloop", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enables the planner's use of nested-loop join plans."),
  			NULL
  		},
  		&enable_nestloop,
  		false, NULL, NULL
  	},
  	{
  		{"enable_mergejoin", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enables the planner's use of merge join plans."),
  			NULL
  		},
  		&enable_mergejoin,
  		false, NULL, NULL
  	},
  	{
  		{"enable_hashjoin", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enables the planner's use of hash join plans."),
  			NULL
  		},
  		&enable_hashjoin,
  		true, NULL, NULL
  	},
  	{
  		{"constraint_exclusion", PGC_USERSET, QUERY_TUNING_OTHER,
  			gettext_noop("Enables the planner to use constraints to optimize queries."),
  			gettext_noop("Child table scans will be skipped if their "
  						 "constraints guarantee that no rows match the query."),
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&constraint_exclusion,
  		true, NULL, NULL
  	},
  	{
  		{"geqo", PGC_USERSET, DEFUNCT_OPTIONS,
  			gettext_noop("Unused. Syntax check only for PostgreSQL compatibility."),
              NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&defunct_bool,
  		false, NULL, NULL
  	},
  
  	{
  		/* Not for general use --- used by SET SESSION AUTHORIZATION */
  		{"is_superuser", PGC_INTERNAL, UNGROUPED,
  			gettext_noop("Shows whether the current user is a superuser."),
  			NULL,
  			GUC_REPORT | GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&session_auth_is_superuser,
  		false, NULL, NULL
  	},
  	{
  		{"ssl", PGC_POSTMASTER, CONN_AUTH_SECURITY,
  			gettext_noop("Enables SSL connections."),
  			NULL
  		},
  		&EnableSSL,
  		false, assign_ssl, NULL
  	},
  	{
  		{"fsync", PGC_SIGHUP, WAL_SETTINGS,
  			gettext_noop("Forces synchronization of updates to disk."),
  			gettext_noop("The server will use the fsync() system call in several places to make "
  			"sure that updates are physically written to disk. This insures "
  						 "that a database cluster will recover to a consistent state after "
  						 "an operating system or hardware crash."),
  		  GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL | GUC_DISALLOW_USER_SET
  		},
  		&enableFsync,
  		true, NULL, NULL
  	},
  	{
  		{"synchronous_commit", PGC_USERSET, WAL_SETTINGS,
  			gettext_noop("Sets immediate fsync at commit."),
  			NULL
  		},
  		&XactSyncCommit,
  		true, NULL, NULL
  	},
  	{
  		{"zero_damaged_pages", PGC_SUSET, DEVELOPER_OPTIONS,
  			gettext_noop("Continues processing past damaged page headers."),
  			gettext_noop("Detection of a damaged page header normally causes PostgreSQL to "
  				"report an error, aborting the current transaction. Setting "
  						 "zero_damaged_pages to true causes the system to instead report a "
  						 "warning, zero out the damaged page, and continue processing. This "
  						 "behavior will destroy data, namely all the rows on the damaged page."),
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&zero_damaged_pages,
  		false, NULL, NULL
  	},
  	{
  		{"full_page_writes", PGC_SIGHUP, WAL_SETTINGS,
  			gettext_noop("Writes full pages to WAL when first modified after a checkpoint."),
  			gettext_noop("A page write in process during an operating system crash might be "
  						 "only partially written to disk.  During recovery, the row changes "
  			  "stored in WAL are not enough to recover.  This option writes "
  						 "pages when first modified after a checkpoint to WAL so full recovery "
  						 "is possible."),
  			 GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&fullPageWrites,
  		true, NULL, NULL
  	},
  	{
  		{"silent_mode", PGC_POSTMASTER, LOGGING_WHEN,
  			gettext_noop("Runs the server silently."),
  			gettext_noop("If this parameter is set, the server will automatically run in the "
  				 "background and any controlling terminals are dissociated."),
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&SilentMode,
  		false, NULL, NULL
  	},
  	{
  		{"log_checkpoints", PGC_SIGHUP, LOGGING_WHAT,
  			gettext_noop("Logs each checkpoint."),
  			NULL
  		},
  		&log_checkpoints,
  		false, NULL, NULL
  	},
  	{
  		{"log_connections", PGC_BACKEND, LOGGING_WHAT,
  			gettext_noop("Logs each successful connection."),
  			NULL
  		},
  		&Log_connections,
  		false, NULL, NULL
  	},
  	{
  		{"log_disconnections", PGC_BACKEND, LOGGING_WHAT,
  			gettext_noop("Logs end of a session, including duration."),
  			NULL
  		},
  		&Log_disconnections,
  		false, NULL, NULL
  	},
  	{
  		{"debug_assertions", PGC_USERSET, DEVELOPER_OPTIONS,
  			gettext_noop("Turns on various assertion checks."),
  			gettext_noop("This is a debugging aid."),
  			GUC_NOT_IN_SAMPLE
  		},
  		&assert_enabled,
  #ifdef USE_ASSERT_CHECKING
  		true,
  #else
  		false,
  #endif
  		assign_debug_assertions, NULL
  	},
  	{
  		/* currently undocumented, so don't show in SHOW ALL */
  		{"exit_on_error", PGC_USERSET, UNGROUPED,
  			gettext_noop("No description available."),
  			NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&ExitOnAnyError,
  		false, NULL, NULL
  	},
  	{
  		{"log_duration", PGC_SUSET, LOGGING_WHAT,
  			gettext_noop("Logs the duration of each completed SQL statement."),
  			NULL,
  			GUC_GPDB_ADDOPT
  		},
  		&log_duration,
  		false, NULL, NULL
  	},
  	{
  		{"debug_print_parse", PGC_USERSET, LOGGING_WHAT,
  			gettext_noop("Prints the parse tree to the server log."),
  			NULL
  		},
  		&Debug_print_parse,
  		false, NULL, NULL
  	},
  	{
  		{"debug_print_rewritten", PGC_USERSET, LOGGING_WHAT,
  			gettext_noop("Prints the parse tree after rewriting to server log."),
  			NULL
  		},
  		&Debug_print_rewritten,
  		false, NULL, NULL
  	},
  	{
  		{"debug_print_plan", PGC_USERSET, LOGGING_WHAT,
  			gettext_noop("Prints the execution plan to server log."),
  			NULL
  		},
  		&Debug_print_plan,
  		false, NULL, NULL
  	},
  	{
  		{"debug_pretty_print", PGC_USERSET, LOGGING_WHAT,
  			gettext_noop("Indents parse and plan tree displays."),
  			NULL
  		},
  		&Debug_pretty_print,
  		false, NULL, NULL
  	},
  	{
  		{"log_parser_stats", PGC_SUSET, STATS_MONITORING,
  			gettext_noop("Writes parser performance statistics to the server log."),
  			NULL
  		},
  		&log_parser_stats,
  		false, assign_stage_log_stats, NULL
  	},
  	{
  		{"log_planner_stats", PGC_SUSET, STATS_MONITORING,
  			gettext_noop("Writes planner performance statistics to the server log."),
  			NULL
  		},
  		&log_planner_stats,
  		false, assign_stage_log_stats, NULL
  	},
  	{
  		{"log_executor_stats", PGC_SUSET, STATS_MONITORING,
  			gettext_noop("Writes executor performance statistics to the server log."),
  			NULL,
  			GUC_GPDB_ADDOPT
  		},
  		&log_executor_stats,
  		false, assign_stage_log_stats, NULL
  	},
  	{
  		{"log_statement_stats", PGC_SUSET, STATS_MONITORING,
  			gettext_noop("Writes cumulative performance statistics to the server log."),
  			NULL,
  			GUC_GPDB_ADDOPT
  		},
  		&log_statement_stats,
  		false, assign_log_stats, NULL
  	},
  #ifdef BTREE_BUILD_STATS
  	{
  		{"log_btree_build_stats", PGC_SUSET, DEVELOPER_OPTIONS,
  			gettext_noop("No description available."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&log_btree_build_stats,
  		false, NULL, NULL
  	},
  #endif
  
  	{
  		{"explain_pretty_print", PGC_USERSET, CLIENT_CONN_OTHER,
  			gettext_noop("Uses the indented output format for EXPLAIN VERBOSE."),
  			NULL
  		},
  		&Explain_pretty_print,
  		true, NULL, NULL
  	},
  
  	{
  		{"track_activities", PGC_SUSET, STATS_COLLECTOR,
  			gettext_noop("Collects information about executing commands."),
  			gettext_noop("Enables the collection of information on the currently "
  						 "executing command of each session, along with "
  						 "the time at which that command began execution.")
  		},
  		&pgstat_track_activities,
  		true, NULL, NULL
  	},
  	{
  		{"track_counts", PGC_SUSET, STATS_COLLECTOR,
  			gettext_noop("Collects statistics on database activity."),
  			NULL
  		},
  		&pgstat_track_counts,
  		true, NULL, NULL
  	},
  
  	{
  		{"stats_queue_level", PGC_SUSET, STATS_COLLECTOR,
  			gettext_noop("Collects resource queue-level statistics on database activity."),
  			NULL
  		},
  		&pgstat_collect_queuelevel,
  		false, NULL, NULL
  	},
  
  	{
  		{"update_process_title", PGC_SUSET, STATS_COLLECTOR,
  			gettext_noop("Updates the process title to show the active SQL command."),
  			gettext_noop("Enables updating of the process title every time a new SQL command is received by the server.")
  		},
  		&update_process_title,
  		true, NULL, NULL
  	},
  
  	{
  		{"autovacuum", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Starts the autovacuum subprocess."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&autovacuum_start_daemon,
  		/*
  		 * GPDB: The default for autovacuum is intentionally 'off', even though it's 'on'
  		 * in PostgreSQL. We may want to revisit this later, but people had bad experience
  		 * with autovacuum on GPDB 4.3 versions. Mainly, it's problematic in a cluster when
  		 * autovacuum kicks in in a single segment: the performance of the cluster is often
  		 * only as good as the slowest segment, so autovacuum running on one segment slows
  		 * down the whole system. Also, auto-analyze is problematic, because we actually
  		 * need to collect statistics across all segments in the master, rather than collect
  		 * per-segment statistics at different times in different segments.
  		 *
  		 * So, disabled by default for now. You can still turn it on manually if you know what
  		 * you're doing (e.g. it might be ok to let autovacuum handle small fact tables and
  		 * catalog tables, and schedule manual vacuums for all the big tables).
  		 */
  		false, NULL, NULL
  	},
  
  	{
  		{"trace_notify", PGC_USERSET, DEVELOPER_OPTIONS,
  			gettext_noop("Generates debugging output for LISTEN and NOTIFY."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&Trace_notify,
  		false, NULL, NULL
  	},
  
  #ifdef LOCK_DEBUG
  	{
  		{"trace_locks", PGC_SUSET, DEVELOPER_OPTIONS,
  			gettext_noop("No description available."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&Trace_locks,
  		false, NULL, NULL
  	},
  	{
  		{"trace_userlocks", PGC_SUSET, DEVELOPER_OPTIONS,
  			gettext_noop("No description available."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&Trace_userlocks,
  		false, NULL, NULL
  	},
  	{
  		{"trace_lwlocks", PGC_SUSET, DEVELOPER_OPTIONS,
  			gettext_noop("No description available."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&Trace_lwlocks,
  		false, NULL, NULL
  	},
  	{
  		{"debug_deadlocks", PGC_SUSET, DEVELOPER_OPTIONS,
  			gettext_noop("No description available."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&Debug_deadlocks,
  		false, NULL, NULL
  	},
  #endif
  
  	{
  		{"log_lock_waits", PGC_SUSET, LOGGING_WHAT,
  			gettext_noop("Logs long lock waits."),
  			NULL
  		},
  		&log_lock_waits,
  		false, NULL, NULL
  	},
  
  	{
  		{"log_hostname", PGC_SIGHUP, LOGGING_WHAT,
  			gettext_noop("Logs the host name in the connection logs."),
  			gettext_noop("By default, connection logs only show the IP address "
  						 "of the connecting host. If you want them to show the host name you "
  			  "can turn this on, but depending on your host name resolution "
  			   "setup it might impose a non-negligible performance penalty.")
  		},
  		&log_hostname,
  		false, NULL, NULL
  	},
  	{
  		{"sql_inheritance", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
  			gettext_noop("Causes subtables to be included by default in various commands."),
  			NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&SQL_inheritance,
  		true, NULL, NULL
  	},
  	{
  		{"password_encryption", PGC_USERSET, CONN_AUTH_SECURITY,
  			gettext_noop("Encrypt passwords."),
  			gettext_noop("When a password is specified in CREATE USER or "
  			   "ALTER USER without writing either ENCRYPTED or UNENCRYPTED, "
  						 "this parameter determines whether the password is to be encrypted.")
  		},
  		&Password_encryption,
  		true, NULL, NULL
  	},
  	{
  		{"transform_null_equals", PGC_USERSET, COMPAT_OPTIONS_CLIENT,
  			gettext_noop("Treats \"expr=NULL\" as \"expr IS NULL\"."),
  			gettext_noop("When turned on, expressions of the form expr = NULL "
  			   "(or NULL = expr) are treated as expr IS NULL, that is, they "
  				"return true if expr evaluates to the null value, and false "
  			   "otherwise. The correct behavior of expr = NULL is to always "
  						 "return null (unknown).")
  		},
  		&Transform_null_equals,
  		false, NULL, NULL
  	},
  	{
  		{"db_user_namespace", PGC_SIGHUP, CONN_AUTH_SECURITY,
  			gettext_noop("Enables per-database user names."),
  			NULL
  		},
  		&Db_user_namespace,
  		false, NULL, NULL
  	},
  	{
  		/* only here for backwards compatibility */
  		{"autocommit", PGC_USERSET, COMPAT_OPTIONS_IGNORED,
  			gettext_noop("This parameter doesn't do anything."),
  			gettext_noop("It's just here so that we won't choke on SET AUTOCOMMIT TO ON from 7.3-vintage clients."),
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&phony_autocommit,
  		true, assign_phony_autocommit, NULL
  	},
  	{
  		{"default_transaction_read_only", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets the default read-only status of new transactions."),
  			NULL
  		},
  		&DefaultXactReadOnly,
  		false, NULL, NULL
  	},
  	{
  		{"transaction_read_only", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets the current transaction's read-only status."),
  			NULL,
  			GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&XactReadOnly,
  		false, assign_transaction_read_only, NULL
  	},
  	{
  		{"add_missing_from", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
  			gettext_noop("Automatically adds missing table references to FROM clauses."),
  			NULL
  		},
  		&add_missing_from,
  		false, NULL, NULL
  	},
  	{
  		{"check_function_bodies", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Check function bodies during CREATE FUNCTION."),
  			NULL
  		},
  		&check_function_bodies,
  		true, NULL, NULL
  	},
  	{
  		{"array_nulls", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
  			gettext_noop("Enable input of NULL elements in arrays."),
  			gettext_noop("When turned on, unquoted NULL in an array input "
  						 "value means a null value; "
  						 "otherwise it is taken literally.")
  		},
  		&Array_nulls,
  		true, NULL, NULL
  	},
  	{
  		{"default_with_oids", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
  			gettext_noop("Create new tables with OIDs by default."),
  			NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&default_with_oids,
  		false, NULL, NULL
  	},
  	{
  		{"logging_collector", PGC_POSTMASTER, DEFUNCT_OPTIONS,
  			gettext_noop("Defunct: Start a subprocess to capture stderr output and/or csvlogs into log files."),
  			NULL
  		},
  		&Logging_collector,
  		true, NULL, NULL
  	},
  	{
  		{"log_truncate_on_rotation", PGC_SIGHUP, LOGGING_WHERE,
  			gettext_noop("Truncate existing log files of same name during log rotation."),
  			NULL
  		},
  		&Log_truncate_on_rotation,
  		false, NULL, NULL
  	},
  
  	{
  		{"trace_sort", PGC_USERSET, DEVELOPER_OPTIONS,
  			gettext_noop("Emit information about resource usage in sorting."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&trace_sort,
  		false, NULL, NULL
  	},
  
  #ifdef TRACE_SYNCSCAN
  	/* this is undocumented because not exposed in a standard build */
  	{
  		{"trace_syncscan", PGC_USERSET, DEVELOPER_OPTIONS,
  			gettext_noop("Generate debugging output for synchronized scanning."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&trace_syncscan,
  		false, NULL, NULL
  	},
  #endif
  
  #ifdef DEBUG_BOUNDED_SORT
  	/* this is undocumented because not exposed in a standard build */
  	{
  		{
  			"optimize_bounded_sort", PGC_USERSET, QUERY_TUNING_METHOD,
  			gettext_noop("Enable bounded sorting using heap sort."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&optimize_bounded_sort,
  		true, NULL, NULL
  	},
  #endif
  
  #ifdef WAL_DEBUG
  	{
  		{"wal_debug", PGC_SUSET, DEVELOPER_OPTIONS,
  			gettext_noop("Emit WAL-related debugging output."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&XLOG_DEBUG,
  		false, NULL, NULL
  	},
  #endif
  
  	{
  		{"integer_datetimes", PGC_INTERNAL, PRESET_OPTIONS,
  			gettext_noop("Datetimes are integer based."),
  			NULL,
  			GUC_REPORT | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&integer_datetimes,
  #ifdef HAVE_INT64_TIMESTAMP
  		true, NULL, NULL
  #else
  		false, NULL, NULL
  #endif
  	},
  
  	{
  		{"krb_caseins_users", PGC_POSTMASTER, CONN_AUTH_SECURITY,
  			gettext_noop("Sets whether Kerberos and GSSAPI user names should be treated as case-insensitive."),
  			NULL
  		},
  		&pg_krb_caseins_users,
  		false, NULL, NULL
  	},
  
  	{
  		{"escape_string_warning", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
  			gettext_noop("Warn about backslash escapes in ordinary string literals."),
  			NULL
  		},
  		&escape_string_warning,
  		true, NULL, NULL
  	},
  
  	{
  		{"standard_conforming_strings", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
  			gettext_noop("Causes '...' strings to treat backslashes literally."),
  			NULL,
  			GUC_REPORT
  		},
  		&standard_conforming_strings,
  		true, NULL, NULL
  	},
  
  	{
  		{"synchronize_seqscans", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
  			gettext_noop("Enable synchronized sequential scans."),
  			NULL
  		},
  		&synchronize_seqscans,
  		true, NULL, NULL
  	},
  
  	{
  		{"archive_mode", PGC_POSTMASTER, WAL_SETTINGS,
  			gettext_noop("Allows archiving of WAL files using archive_command."),
  			NULL
  		},
  		&XLogArchiveMode,
  		false, NULL, NULL
  	},
  
  	{
  		{"ignore_system_indexes", PGC_BACKEND, DEVELOPER_OPTIONS,
  			gettext_noop("Disables reading from system indexes."),
  			gettext_noop("It does not prevent updating the indexes, so it is safe "
  						 "to use.  The worst consequence is slowness."),
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&IgnoreSystemIndexes,
  		false, NULL, NULL
  	},
  
  	/* End-of-list marker */
  	{
  		{NULL, 0, 0, NULL, NULL}, NULL, false, NULL, NULL
  	}
  };
  
  
  static struct config_int ConfigureNamesInt[] =
  {
  	{
  		{"archive_timeout", PGC_SIGHUP, WAL_SETTINGS,
  			gettext_noop("Forces a switch to the next xlog file if a "
  						 "new file has not been started within N seconds."),
  			NULL,
  			GUC_UNIT_S | GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&XLogArchiveTimeout,
  		0, 0, INT_MAX / 2, NULL, NULL
  	},
  	{
  		{"post_auth_delay", PGC_BACKEND, DEVELOPER_OPTIONS,
  			gettext_noop("Waits N seconds on connection startup after authentication."),
  			gettext_noop("This allows attaching a debugger to the process."),
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL | GUC_UNIT_S
  		},
  		&PostAuthDelay,
  		0, 0, INT_MAX / 1000000, NULL, NULL
  	},
  	{
  		{"default_statistics_target", PGC_USERSET, STATS_ANALYZE,
  			gettext_noop("Sets the default statistics target."),
  			gettext_noop("This applies to table columns that have not had a "
  				"column-specific target set via ALTER TABLE SET STATISTICS.")
  		},
  		&default_statistics_target,
  		25, 1, 1000, NULL, NULL
  	},
  	{
  		{"from_collapse_limit", PGC_USERSET, QUERY_TUNING_OTHER,
  			gettext_noop("Sets the FROM-list size beyond which subqueries "
  						 "are not collapsed."),
  			gettext_noop("The planner will merge subqueries into upper "
  				"queries if the resulting FROM list would have no more than "
  						 "this many items.")
  		},
  		&from_collapse_limit,
  		20, 1, INT_MAX, NULL, NULL
  	},
  	{
  		{"join_collapse_limit", PGC_USERSET, QUERY_TUNING_OTHER,
  			gettext_noop("Sets the FROM-list size beyond which JOIN "
  						 "constructs are not flattened."),
  			gettext_noop("The planner will flatten explicit JOIN "
  						 "constructs into lists of FROM items whenever a "
  						 "list of no more than this many items would result.")
  		},
  		&join_collapse_limit,
  		20, 1, INT_MAX, NULL, NULL
  	},
  	{
  		{"geqo_threshold", PGC_USERSET, DEFUNCT_OPTIONS,
  			gettext_noop("Unused. Syntax check only for PostgreSQL compatibility."),
              NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&defunct_int,
  		12, 2, INT_MAX, NULL, NULL
  	},
  	{
  		{"geqo_effort", PGC_USERSET, DEFUNCT_OPTIONS,
  			gettext_noop("Unused. Syntax check only for PostgreSQL compatibility."),
              NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&defunct_int,
  		//DEFAULT_GEQO_EFFORT, MIN_GEQO_EFFORT, MAX_GEQO_EFFORT, NULL, NULL
  		0, 0, INT_MAX, NULL, NULL
  	},
  	{
  		{"geqo_pool_size", PGC_USERSET, DEFUNCT_OPTIONS,
  			gettext_noop("Unused. Syntax check only for PostgreSQL compatibility."),
              NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&defunct_int,
  		0, 0, INT_MAX, NULL, NULL
  	},
  	{
  		{"geqo_generations", PGC_USERSET, DEFUNCT_OPTIONS,
  			gettext_noop("Unused. Syntax check only for PostgreSQL compatibility."),
              NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&defunct_int,
  		0, 0, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"deadlock_timeout", PGC_SIGHUP, LOCK_MANAGEMENT,
  			gettext_noop("Sets the time to wait on a lock before checking for deadlock."),
  			NULL,
  			GUC_UNIT_MS
  		},
  		&DeadlockTimeout,
  		1000, 1, INT_MAX / 1000, NULL, NULL
  	},
  
  	/*
  	 * Note: There is some postprocessing done in PostmasterMain() to make
  	 * sure the buffers are at least twice the number of backends, so the
  	 * constraints here are partially unused. Similarly, the superuser
  	 * reserved number is checked to ensure it is less than the max backends
  	 * number.
  	 *
  	 * MaxBackends is limited to INT_MAX/4 because some places compute
  	 * 4*MaxBackends without any overflow check.  This check is made on
  	 * assign_maxconnections, since MaxBackends is computed as MaxConnections
  	 * + autovacuum_max_workers.
  	 *
  	 * Likewise we have to limit NBuffers to INT_MAX/2.
  	 */
  	{
  		{"max_connections", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
  			gettext_noop("Sets the maximum number of concurrent connections."),
  			NULL
  		},
  		&MaxConnections,
  		200, 10, MAX_MAX_BACKENDS, assign_maxconnections, NULL
  	},
  
  	{
  		{"superuser_reserved_connections", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
  			gettext_noop("Sets the number of connection slots reserved for superusers."),
  			NULL
  		},
  		&ReservedBackends,
  		3, 0, INT_MAX / 4, NULL, NULL
  	},
  
  	{
  		{"shared_buffers", PGC_POSTMASTER, RESOURCES_MEM,
  			gettext_noop("Sets the number of shared memory buffers used by the server."),
  			NULL,
  			GUC_UNIT_BLOCKS
  		},
  		&NBuffers,
  		4096, 16, INT_MAX / 2, NULL, NULL
  	},
  
  	{
  		{"temp_buffers", PGC_USERSET, RESOURCES_MEM,
  			gettext_noop("Sets the maximum number of temporary buffers used by each session."),
  			NULL,
  			GUC_UNIT_BLOCKS | GUC_GPDB_ADDOPT
  		},
  		&num_temp_buffers,
  		1024, 100, INT_MAX / 2, NULL, show_num_temp_buffers
  	},
  
  	{
  		{"port", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
  			gettext_noop("Sets the TCP port the server listens on."),
  			NULL
  		},
  		&PostPortNumber,
  		DEF_PGPORT, 1, 65535, NULL, NULL
  	},
  
  	{
  		{"unix_socket_permissions", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
  			gettext_noop("Sets the access permissions of the Unix-domain socket."),
  			gettext_noop("Unix-domain sockets use the usual Unix file system "
  						 "permission set. The parameter value is expected to be an numeric mode "
  						 "specification in the form accepted by the chmod and umask system "
  						 "calls. (To use the customary octal format the number must start with "
  						 "a 0 (zero).)")
  		},
  		&Unix_socket_permissions,
  		0777, 0000, 0777, NULL, NULL
  	},
  
  	{
  		{"work_mem", PGC_USERSET, DEPRECATED_OPTIONS,
  			gettext_noop("Sets the maximum memory to be used for query workspaces."),
  			gettext_noop("This much memory can be used by each internal "
  						 "sort operation and hash table before switching to "
  						 "temporary disk files."),
  			GUC_UNIT_KB | GUC_GPDB_ADDOPT
  		},
  		&work_mem,
          32768, 64, MAX_KILOBYTES, NULL, NULL
  	},
  
  	{
  		{"maintenance_work_mem", PGC_USERSET, RESOURCES_MEM,
  			gettext_noop("Sets the maximum memory to be used for maintenance operations."),
  			gettext_noop("This includes operations such as VACUUM and CREATE INDEX."),
  			GUC_UNIT_KB | GUC_GPDB_ADDOPT
  		},
  		&maintenance_work_mem,
  		65536, 1024, MAX_KILOBYTES, NULL, NULL
  	},
  
  	{
  		{"max_stack_depth", PGC_SUSET, RESOURCES_MEM,
  			gettext_noop("Sets the maximum stack depth, in kilobytes."),
  			NULL,
  			GUC_UNIT_KB
  		},
  		&max_stack_depth,
  		100, 100, MAX_KILOBYTES, assign_max_stack_depth, NULL
  	},
  
  	{
  		{"vacuum_cost_page_hit", PGC_USERSET, RESOURCES,
  			gettext_noop("Vacuum cost for a page found in the buffer cache."),
  			NULL
  		},
  		&VacuumCostPageHit,
  		1, 0, 10000, NULL, NULL
  	},
  
  	{
  		{"vacuum_cost_page_miss", PGC_USERSET, RESOURCES,
  			gettext_noop("Vacuum cost for a page not found in the buffer cache."),
  			NULL
  		},
  		&VacuumCostPageMiss,
  		10, 0, 10000, NULL, NULL
  	},
  
  	{
  		{"vacuum_cost_page_dirty", PGC_USERSET, RESOURCES,
  			gettext_noop("Vacuum cost for a page dirtied by vacuum."),
  			NULL
  		},
  		&VacuumCostPageDirty,
  		20, 0, 10000, NULL, NULL
  	},
  
  	{
  		{"vacuum_cost_limit", PGC_USERSET, RESOURCES,
  			gettext_noop("Vacuum cost amount available before napping."),
  			NULL
  		},
  		&VacuumCostLimit,
  		200, 1, 10000, NULL, NULL
  	},
  
  	{
  		{"vacuum_cost_delay", PGC_USERSET, RESOURCES,
  			gettext_noop("Vacuum cost delay in milliseconds."),
  			NULL,
  			GUC_UNIT_MS
  		},
  		&VacuumCostDelay,
  		0, 0, 1000, NULL, NULL
  	},
  
  	{
  		{"autovacuum_vacuum_cost_delay", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Vacuum cost delay in milliseconds, for autovacuum."),
  			NULL,
  			GUC_UNIT_MS | GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&autovacuum_vac_cost_delay,
  		20, -1, 1000, NULL, NULL
  	},
  
  	{
  		{"autovacuum_vacuum_cost_limit", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Vacuum cost amount available before napping, for autovacuum."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&autovacuum_vac_cost_limit,
  		-1, -1, 10000, NULL, NULL
  	},
  
  	{
  		{"max_files_per_process", PGC_POSTMASTER, RESOURCES_KERNEL,
  			gettext_noop("Sets the maximum number of simultaneously open files for each server process."),
  			NULL
  		},
  		&max_files_per_process,
  		1000, 25, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"max_prepared_transactions", PGC_POSTMASTER, RESOURCES,
  			gettext_noop("Sets the maximum number of simultaneously prepared transactions."),
              NULL
  		},
  		&max_prepared_xacts,
  		50, 1, 1000, NULL, NULL
  	},
  
  #ifdef LOCK_DEBUG
  	{
  		{"trace_lock_oidmin", PGC_SUSET, DEVELOPER_OPTIONS,
  			gettext_noop("No description available."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&Trace_lock_oidmin,
  		FirstNormalObjectId, 0, INT_MAX, NULL, NULL
  	},
  	{
  		{"trace_lock_table", PGC_SUSET, DEVELOPER_OPTIONS,
  			gettext_noop("No description available."),
  			NULL,
  			GUC_NOT_IN_SAMPLE
  		},
  		&Trace_lock_table,
  		0, 0, INT_MAX, NULL, NULL
  	},
  #endif
  
  	{
  		{"statement_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets the maximum allowed duration of any statement."),
  			gettext_noop("A value of 0 turns off the timeout."),
  			GUC_UNIT_MS | GUC_GPDB_ADDOPT
  		},
  		&StatementTimeout,
  		0, 0, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"vacuum_freeze_min_age", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Minimum age at which VACUUM should freeze a table row."),
  			NULL
  		},
  		&vacuum_freeze_min_age,
  		100000000, 0, 1000000000, NULL, NULL
  	},
  
  	{
  		{"max_fsm_relations", PGC_POSTMASTER, RESOURCES_FSM,
  			gettext_noop("Sets the maximum number of tables and indexes for which free space is tracked."),
  			NULL
  		},
  		&MaxFSMRelations,
  		1000, 100, INT_MAX, NULL, NULL
  	},
  	{
  		{"max_fsm_pages", PGC_POSTMASTER, RESOURCES_FSM,
  			gettext_noop("Sets the maximum number of disk pages for which free space is tracked."),
  			NULL
  		},
  		&MaxFSMPages,
  		20000, 1000, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"max_locks_per_transaction", PGC_POSTMASTER, LOCK_MANAGEMENT,
  			gettext_noop("Sets the maximum number of locks per transaction."),
  			gettext_noop("The shared lock table is sized on the assumption that "
  			  "at most max_locks_per_transaction * max_connections distinct "
  						 "objects will need to be locked at any one time.")
  		},
  		&max_locks_per_xact,
  		128, 10, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"authentication_timeout", PGC_SIGHUP, CONN_AUTH_SECURITY,
  			gettext_noop("Sets the maximum allowed time to complete client authentication."),
  			NULL,
  			GUC_UNIT_S
  		},
  		&AuthenticationTimeout,
  		60, 1, 600, NULL, NULL
  	},
  
  	{
  		/* Not for general use */
  		{"pre_auth_delay", PGC_SIGHUP, DEVELOPER_OPTIONS,
  			gettext_noop("Waits N seconds on connection startup before authentication."),
  			gettext_noop("This allows attaching a debugger to the process."),
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL | GUC_UNIT_S
  		},
  		&PreAuthDelay,
  		0, 0, 60, NULL, NULL
  	},
  
  	{
  		{"checkpoint_segments", PGC_SIGHUP, WAL_CHECKPOINTS,
  			gettext_noop("Sets the maximum distance in log segments between automatic WAL checkpoints."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&CheckPointSegments,
  		8, 1, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"checkpoint_timeout", PGC_SIGHUP, WAL_CHECKPOINTS,
  			gettext_noop("Sets the maximum time between automatic WAL checkpoints."),
  			NULL,
  			GUC_UNIT_S | GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL | GUC_DISALLOW_USER_SET
  		},
  		&CheckPointTimeout,
  		300, 30, 3600, NULL, NULL
  	},
  
  	{
  		{"checkpoint_warning", PGC_SIGHUP, WAL_CHECKPOINTS,
  			gettext_noop("Enables warnings if checkpoint segments are filled more "
  						 "frequently than this."),
  			gettext_noop("Write a message to the server log if checkpoints "
  			"caused by the filling of checkpoint segment files happens more "
  						 "frequently than this number of seconds. Zero turns off the warning."),
  			GUC_UNIT_S | GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&CheckPointWarning,
  		30, 0, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"wal_buffers", PGC_POSTMASTER, WAL_SETTINGS,
  			gettext_noop("Sets the number of disk-page buffers in shared memory for WAL."),
  			NULL,
  			GUC_UNIT_XBLOCKS | GUC_NOT_IN_SAMPLE
  		},
  		&XLOGbuffers,
  		8, 4, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"wal_writer_delay", PGC_SIGHUP, WAL_SETTINGS,
  			gettext_noop("WAL writer sleep time between WAL flushes."),
  			NULL,
  			GUC_UNIT_MS
  		},
  		&WalWriterDelay,
  		200, 1, 10000, NULL, NULL
  	},
  
  	{
  		{"commit_delay", PGC_USERSET, WAL_SETTINGS,
  			gettext_noop("Sets the delay in microseconds between transaction commit and "
  						 "flushing WAL to disk."),
  			NULL,
  			GUC_GPDB_ADDOPT | GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL | GUC_DISALLOW_USER_SET
  		},
  		&CommitDelay,
  		0, 0, 100000, NULL, NULL
  	},
  
  	{
  		{"commit_siblings", PGC_USERSET, WAL_SETTINGS,
  			gettext_noop("Sets the minimum concurrent open transactions before performing "
  						 "commit_delay."),
  			NULL,
  			GUC_GPDB_ADDOPT | GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL | GUC_DISALLOW_USER_SET
  		},
  		&CommitSiblings,
  		5, 1, 1000, NULL, NULL
  	},
  
  	{
  		{"extra_float_digits", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the number of digits displayed for floating-point values."),
  			gettext_noop("This affects real, double precision, and geometric data types. "
  			 "The parameter value is added to the standard number of digits "
  						 "(FLT_DIG or DBL_DIG as appropriate).")
  		},
  		&extra_float_digits,
  		0, -15, 2, NULL, NULL
  	},
  
  	{
  		{"log_min_duration_statement", PGC_SUSET, LOGGING_WHEN,
  			gettext_noop("Sets the minimum execution time above which "
  						 "statements will be logged."),
  			gettext_noop("Zero prints all queries. -1 turns this feature off."),
  			GUC_UNIT_MS | GUC_GPDB_ADDOPT
  		},
  		&log_min_duration_statement,
  		-1, -1, INT_MAX / 1000, NULL, NULL
  	},
  
  	{
  		{"log_autovacuum_min_duration", PGC_SIGHUP, LOGGING_WHAT,
  			gettext_noop("Sets the minimum execution time above which "
  						 "autovacuum actions will be logged."),
  			gettext_noop("Zero prints all actions. -1 turns autovacuum logging off."),
  			GUC_UNIT_MS
  		},
  		&Log_autovacuum_min_duration,
  		-1, -1, INT_MAX / 1000, NULL, NULL
  	},
  
  	{
  		{"bgwriter_delay", PGC_SIGHUP, RESOURCES,
  			gettext_noop("Background writer sleep time between rounds."),
  			NULL,
  			GUC_UNIT_MS | GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&BgWriterDelay,
  		200, 10, 10000, NULL, NULL
  	},
  
  	{
  		{"bgwriter_lru_maxpages", PGC_SIGHUP, RESOURCES,
  			gettext_noop("Background writer maximum number of LRU pages to flush per round."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&bgwriter_lru_maxpages,
  		100, 0, 1000, NULL, NULL
  	},
  
  	{
  		{"log_rotation_age", PGC_SIGHUP, LOGGING_WHERE,
  			gettext_noop("Automatic log file rotation will occur after N minutes."),
  			NULL,
  			GUC_UNIT_MIN
  		},
  		&Log_RotationAge,
  		HOURS_PER_DAY * MINS_PER_HOUR, 0, INT_MAX / MINS_PER_HOUR, NULL, NULL
  	},
  
  	{
  		{"log_rotation_size", PGC_SIGHUP, LOGGING_WHERE,
  			gettext_noop("Automatic log file rotation will occur after N kilobytes."),
  			NULL,
  			GUC_UNIT_KB
  		},
  		&Log_RotationSize,
  		0, 0, INT_MAX / 1024, NULL, NULL
  	},
  
  	{
  		{"max_function_args", PGC_INTERNAL, PRESET_OPTIONS,
  			gettext_noop("Shows the maximum number of function arguments."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&max_function_args,
  		FUNC_MAX_ARGS, FUNC_MAX_ARGS, FUNC_MAX_ARGS, NULL, NULL
  	},
  
  	{
  		{"max_index_keys", PGC_INTERNAL, PRESET_OPTIONS,
  			gettext_noop("Shows the maximum number of index keys."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&max_index_keys,
  		INDEX_MAX_KEYS, INDEX_MAX_KEYS, INDEX_MAX_KEYS, NULL, NULL
  	},
  
  	{
  		{"max_identifier_length", PGC_INTERNAL, PRESET_OPTIONS,
  			gettext_noop("Shows the maximum identifier length."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&max_identifier_length,
  		NAMEDATALEN - 1, NAMEDATALEN - 1, NAMEDATALEN - 1, NULL, NULL
  	},
  
  	{
  		{"block_size", PGC_INTERNAL, PRESET_OPTIONS,
  			gettext_noop("Shows the size of a disk block."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&block_size,
  		BLCKSZ, BLCKSZ, BLCKSZ, NULL, NULL
  	},
  	{
  		/* see max_connections */
  		{"autovacuum_max_workers", PGC_POSTMASTER, AUTOVACUUM,
  			gettext_noop("Sets the maximum number of simultaneously running autovacuum worker processes."),
  			NULL
  		},
  		&autovacuum_max_workers,
  		3, 1, INT_MAX / 4, assign_autovacuum_max_workers, NULL
  	},
  
  	{
  		{"autovacuum_naptime", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Time to sleep between autovacuum runs."),
  			NULL,
  			GUC_UNIT_S | GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&autovacuum_naptime,
  		60, 1, INT_MAX / 1000, NULL, NULL
  	},
  	{
  		{"autovacuum_vacuum_threshold", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Minimum number of tuple updates or deletes prior to vacuum."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&autovacuum_vac_thresh,
  		50, 0, INT_MAX, NULL, NULL
  	},
  	{
  		{"autovacuum_analyze_threshold", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Minimum number of tuple inserts, updates or deletes prior to analyze."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&autovacuum_anl_thresh,
  		50, 0, INT_MAX, NULL, NULL
  	},
  	{
  		/* see varsup.c for why this is PGC_POSTMASTER not PGC_SIGHUP */
  		{"autovacuum_freeze_max_age", PGC_POSTMASTER, DEFUNCT_OPTIONS,
  			gettext_noop("Age at which to autovacuum a table to prevent transaction ID wraparound."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&autovacuum_freeze_max_age,
  		200000000, 1000, 2000000000, NULL, NULL
  	},
  	{
  		/* see max_connections */
  		{"autovacuum_max_workers", PGC_POSTMASTER, AUTOVACUUM,
  			gettext_noop("Sets the maximum number of simultaneously running autovacuum worker processes."),
  			NULL
  		},
  		&autovacuum_max_workers,
  		3, 1, INT_MAX / 4, assign_autovacuum_max_workers, NULL
  	},
  
  	{
  		{"tcp_keepalives_idle", PGC_USERSET, CLIENT_CONN_OTHER,
  			gettext_noop("Time between issuing TCP keepalives."),
  			gettext_noop("A value of 0 uses the system default."),
  			GUC_UNIT_S
  		},
  		&tcp_keepalives_idle,
  		0, 0, INT_MAX, assign_tcp_keepalives_idle, show_tcp_keepalives_idle
  	},
  
  	{
  		{"tcp_keepalives_interval", PGC_USERSET, CLIENT_CONN_OTHER,
  			gettext_noop("Time between TCP keepalive retransmits."),
  			gettext_noop("A value of 0 uses the system default."),
  			GUC_UNIT_S
  		},
  		&tcp_keepalives_interval,
  		0, 0, INT_MAX, assign_tcp_keepalives_interval, show_tcp_keepalives_interval
  	},
  
  	{
  		{"ssl_renegotiation_limit", PGC_USERSET, CONN_AUTH_SECURITY,
  			gettext_noop("Set the amount of traffic to send and receive before renegotiating the encryption keys."),
  			NULL,
  			GUC_UNIT_KB,
  		},
  		&ssl_renegotiation_limit,
  		512 * 1024, 0, MAX_KILOBYTES, NULL, NULL
  	},
  
  	{
  		{"tcp_keepalives_count", PGC_USERSET, CLIENT_CONN_OTHER,
  			gettext_noop("Maximum number of TCP keepalive retransmits."),
  			gettext_noop("This controls the number of consecutive keepalive retransmits that can be "
  						 "lost before a connection is considered dead. A value of 0 uses the "
  						 "system default."),
  		},
  		&tcp_keepalives_count,
  		0, 0, INT_MAX, assign_tcp_keepalives_count, show_tcp_keepalives_count
  	},
  
  	/* MPP-9413: gin indexes are disabled */
  	{
  		{"gin_fuzzy_search_limit", PGC_USERSET, CLIENT_CONN_OTHER,
  			gettext_noop("Sets the maximum allowed result for exact search by GIN."),
  			NULL,
              GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&GinFuzzySearchLimit,
  		0, 0, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"effective_cache_size", PGC_USERSET, QUERY_TUNING_COST,
  			gettext_noop("Sets the planner's assumption about the size of the disk cache."),
  			gettext_noop("That is, the portion of the kernel's disk cache that "
  						 "will be used for PostgreSQL data files. This is measured in disk "
  						 "pages, which are normally 8 kB each."),
  			GUC_UNIT_BLOCKS,
  		},
  		&effective_cache_size,
  		DEFAULT_EFFECTIVE_CACHE_SIZE, 1, INT_MAX, NULL, NULL
  	},
  
  	{
  		/* Can't be set in postgresql.conf */
  		{"server_version_num", PGC_INTERNAL, PRESET_OPTIONS,
  			gettext_noop("Shows the server version as an integer."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&server_version_num,
  		PG_VERSION_NUM, PG_VERSION_NUM, PG_VERSION_NUM, NULL, NULL
  	},
  
  	{
  		{"log_temp_files", PGC_USERSET, LOGGING_WHAT,
  			gettext_noop("Log the use of temporary files larger than this number of kilobytes."),
  			gettext_noop("Zero logs all files. The default is -1 (turning this feature off)."),
  			GUC_UNIT_KB
  		},
  		&log_temp_files,
  		-1, -1, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"pgstat_track_activity_query_size", PGC_POSTMASTER, UNGROUPED,
  		gettext_noop("Maximum length of the query to be displayed in pg_stat_activity"),
  		NULL,
  		GUC_NOT_IN_SAMPLE
  		},
  		&pgstat_track_activity_query_size,
  		1024, 1024, INT_MAX,
  		NULL, NULL
  	},
  
  	{
  		{"keep_wal_segments", PGC_SIGHUP, WAL_SETTINGS,
  			gettext_noop("Sets the number of WAL files held for standby servers."),
  			NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&keep_wal_segments,
  		5, 0, INT_MAX, NULL, NULL
  	},
  
  	{
  		{"wal_receiver_status_interval", PGC_SUSET, WAL_REPLICATION,
  			gettext_noop("Sets the maximum interval between WAL receiver "
  						 "status reports to the primary. (Master Mirroring)"),
  			NULL,
  			GUC_UNIT_S
  		},
  		&wal_receiver_status_interval,
  		10, 0, INT_MAX / 1000, NULL, NULL
  	},
  
  	{
  		{"replication_timeout", PGC_SUSET, WAL_REPLICATION,
  			gettext_noop("Sets the maximum time to wait for WAL replication (Master Mirroring)"),
  			NULL,
  			GUC_UNIT_MS | GUC_SUPERUSER_ONLY
  		},
  		&replication_timeout,
  		60 * 1000, 0, INT_MAX, NULL, NULL
  	},
  
  	/* End-of-list marker */
  	{
  		{NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL
  	}
  };
  
  
  static struct config_real ConfigureNamesReal[] =
  {
  	{
  		{"seq_page_cost", PGC_USERSET, QUERY_TUNING_COST,
  			gettext_noop("Sets the planner's estimate of the cost of a "
  						 "sequentially fetched disk page."),
  			NULL
  		},
  		&seq_page_cost,
  		DEFAULT_SEQ_PAGE_COST, 0, DBL_MAX, NULL, NULL
  	},
  	{
  		{"random_page_cost", PGC_USERSET, QUERY_TUNING_COST,
  			gettext_noop("Sets the planner's estimate of the cost of a "
  						 "nonsequentially fetched disk page."),
  			NULL
  		},
  		&random_page_cost,
  		DEFAULT_RANDOM_PAGE_COST, 0, DBL_MAX, NULL, NULL
  	},
  	{
  		{"cpu_tuple_cost", PGC_USERSET, QUERY_TUNING_COST,
  			gettext_noop("Sets the planner's estimate of the cost of "
  						 "processing each tuple (row)."),
  			NULL
  		},
  		&cpu_tuple_cost,
  		DEFAULT_CPU_TUPLE_COST, 0, DBL_MAX, NULL, NULL
  	},
  	{
  		{"cpu_index_tuple_cost", PGC_USERSET, QUERY_TUNING_COST,
  			gettext_noop("Sets the planner's estimate of the cost of "
  						 "processing each index entry during an index scan."),
  			NULL
  		},
  		&cpu_index_tuple_cost,
  		DEFAULT_CPU_INDEX_TUPLE_COST, 0, DBL_MAX, NULL, NULL
  	},
  	{
  		{"cpu_operator_cost", PGC_USERSET, QUERY_TUNING_COST,
  			gettext_noop("Sets the planner's estimate of the cost of "
  						 "processing each operator or function call."),
  			NULL
  		},
  		&cpu_operator_cost,
  		DEFAULT_CPU_OPERATOR_COST, 0, DBL_MAX, NULL, NULL
  	},
  
  	{
  		{"geqo_selection_bias", PGC_USERSET, DEFUNCT_OPTIONS,
  			gettext_noop("Unused. Syntax check only for PostgreSQL compatibility."),
              NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&defunct_double,
  		1.0, 0.0, 100.0, NULL, NULL
  	},
  	{
  		{"bgwriter_lru_multiplier", PGC_SIGHUP, RESOURCES,
  			gettext_noop("Background writer multiplier on average buffers to scan per round."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&bgwriter_lru_multiplier,
  		2.0, 0.0, 10.0, NULL, NULL
  	},
  
  	{
  		{"seed", PGC_USERSET, UNGROUPED,
  			gettext_noop("Sets the seed for random-number generation."),
  			NULL,
  			GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&phony_random_seed,
  		0.5, 0.0, 1.0, assign_random_seed, show_random_seed
  	},
  
  	{
  		{"autovacuum_vacuum_scale_factor", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Number of tuple updates or deletes prior to vacuum as a fraction of reltuples."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&autovacuum_vac_scale,
  		0.2, 0.0, 100.0, NULL, NULL
  	},
  	{
  		{"autovacuum_analyze_scale_factor", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Number of tuple inserts, updates or deletes prior to analyze as a fraction of reltuples."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&autovacuum_anl_scale,
  		0.1, 0.0, 100.0, NULL, NULL
  	},
  
  	{
  		{"checkpoint_completion_target", PGC_SIGHUP, WAL_CHECKPOINTS,
  			gettext_noop("Time spent flushing dirty buffers during checkpoint, as fraction of checkpoint interval."),
  			NULL
  		},
  		&CheckPointCompletionTarget,
  		0.5, 0.0, 1.0, NULL, NULL
  	},
  
  	/* End-of-list marker */
  	{
  		{NULL, 0, 0, NULL, NULL}, NULL, 0.0, 0.0, 0.0, NULL, NULL
  	}
  };
  
  
  static struct config_string ConfigureNamesString[] =
  {
  	{
  		{"allow_system_table_mods", PGC_USERSET, CUSTOM_OPTIONS,
  			gettext_noop("Allows ddl/dml modifications of system tables."),
  			gettext_noop("Valid values are \"NONE\", \"DDL\", \"DML\", \"ALL\". " ),
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&allow_system_table_mods_str,
  		"none", assign_allow_system_table_mods, show_allow_system_table_mods
  	},
  
  	{
  		{"archive_command", PGC_SIGHUP, WAL_SETTINGS,
  			gettext_noop("Sets the shell command that will be called to archive a WAL file."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL
  		},
  		&XLogArchiveCommand,
  		"", NULL, show_archive_command
  	},
  
  	{
  		{"backslash_quote", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
  			gettext_noop("Sets whether \"\\'\" is allowed in string literals."),
  			gettext_noop("Valid values are ON, OFF, and SAFE_ENCODING.")
  		},
  		&backslash_quote_string,
  		"safe_encoding", assign_backslash_quote, NULL
  	},
  
  	{
  		{"client_encoding", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the client's character set encoding."),
  			NULL,
  			GUC_IS_NAME | GUC_REPORT
  		},
  		&client_encoding_string,
  		"SQL_ASCII", assign_client_encoding, NULL
  	},
  
  	{
  		{"client_min_messages", PGC_USERSET, LOGGING_WHEN,
  			gettext_noop("Sets the message levels that are sent to the client."),
  			gettext_noop("Valid values are DEBUG5, DEBUG4, DEBUG3, DEBUG2, "
  						 "DEBUG1, LOG, NOTICE, WARNING, and ERROR. Each level includes all the "
  						 "levels that follow it. The later the level, the fewer messages are "
  						 "sent."),
  			GUC_GPDB_ADDOPT
  		},
  		&client_min_messages_str,
  		"notice", assign_client_min_messages, NULL
  	},
  
  	{
  		{"log_min_messages", PGC_SUSET, LOGGING_WHEN,
  			gettext_noop("Sets the message levels that are logged."),
  			gettext_noop("Valid values are DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1, "
  			"INFO, NOTICE, WARNING, ERROR, LOG, FATAL, and PANIC. Each level "
  						 "includes all the levels that follow it."),
  			GUC_GPDB_ADDOPT
  		},
  		&log_min_messages_str,
  		"warning", assign_log_min_messages, NULL
  	},
  
  	{
  		{"IntervalStyle", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the display format for interval values."),
  			NULL,
  			GUC_REPORT
  		},
  		&IntervalStyle_string,
  		"postgres", assign_IntervalStyle, show_IntervalStyle
  	},
  
  	{
  		{"log_error_verbosity", PGC_SUSET, LOGGING_WHEN,
  			gettext_noop("Sets the verbosity of logged messages."),
  			gettext_noop("Valid values are \"terse\", \"default\", and \"verbose\"."),
  			GUC_GPDB_ADDOPT
  		},
  		&log_error_verbosity_str,
  		"default", assign_log_error_verbosity, NULL
  	},
  	{
  		{"log_statement", PGC_SUSET, LOGGING_WHAT,
  			gettext_noop("Sets the type of statements logged."),
  			gettext_noop("Valid values are \"none\", \"ddl\", \"mod\", and \"all\".")
  		},
  		&log_statement_str,
  		"none", assign_log_statement, NULL
  	},
  
  	{
  		{"log_min_error_statement", PGC_SUSET, LOGGING_WHEN,
  			gettext_noop("Causes all statements generating error at or above this level to be logged."),
  			gettext_noop("All SQL statements that cause an error of the "
  						 "specified level or a higher level are logged."),
  			GUC_GPDB_ADDOPT
  		},
  		&log_min_error_statement_str,
  		"error", assign_min_error_statement, NULL
  	},
  
  	{
  		{"log_line_prefix", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Controls information prefixed to each log line."),
  			gettext_noop("If blank, no prefix is used."),
  			GUC_NO_SHOW_ALL
  		},
  		&Log_line_prefix,
  		"%m|%u|%d|%p|%I|%X|:-", NULL, NULL
  	},
  
  	{
  		{"log_timezone", PGC_SIGHUP, LOGGING_WHAT,
  			gettext_noop("Sets the time zone to use in log messages."),
  			NULL
  		},
  		&log_timezone_string,
  		"UNKNOWN", assign_log_timezone, show_log_timezone
  	},
  
  	{
  		{"DateStyle", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the display format for date and time values."),
  			gettext_noop("Also controls interpretation of ambiguous "
  						 "date inputs."),
  			GUC_LIST_INPUT | GUC_REPORT | GUC_GPDB_ADDOPT
  		},
  		&datestyle_string,
  		"ISO, MDY", assign_datestyle, NULL
  	},
  
  	{
  		{"default_tablespace", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets the default tablespace to create tables and indexes in."),
  			gettext_noop("An empty string selects the database's default tablespace."),
  			GUC_IS_NAME
  		},
  		&default_tablespace,
  		"", assign_default_tablespace, NULL
  	},
  
  /*
   * GPDB_83_MERGE_FIXME: what to do with temp tablespaces in GPDB? we
   * had something similar with filespaces, I think. See also comments in
   * OpenTemporaryFile()
   */
  #if 0
  	{
  		{"temp_tablespaces", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets the tablespace(s) to use for temporary tables and sort files."),
  			NULL,
  			GUC_LIST_INPUT | GUC_LIST_QUOTE
  		},
  		&temp_tablespaces,
  		"", assign_temp_tablespaces, NULL
  	},
  #endif
  	{
  		{"default_transaction_isolation", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets the transaction isolation level of each new transaction."),
  			gettext_noop("Each SQL transaction has an isolation level, which "
  						 "can be either \"read uncommitted\", \"read committed\", \"repeatable read\", or \"serializable\"."),
  		},
  		&default_iso_level_string,
  		"read committed", assign_defaultxactisolevel, NULL
  	},
  
  	{
  		{"session_replication_role", PGC_SUSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets the session's behavior for triggers and rewrite rules."),
  			gettext_noop("Each session can be either"
  						 " \"origin\", \"replica\", or \"local\".")
  		},
  		&session_replication_role_string,
  		"origin", assign_session_replication_role, NULL
  	},
  
  	{
  		{"dynamic_library_path", PGC_SUSET, CLIENT_CONN_OTHER,
  			gettext_noop("Sets the path for dynamically loadable modules."),
  			gettext_noop("If a dynamically loadable module needs to be opened and "
  						 "the specified name does not have a directory component (i.e., the "
  						 "name does not contain a slash), the system will search this path for "
  						 "the specified file."),
  			GUC_SUPERUSER_ONLY
  		},
  		&Dynamic_library_path,
  		"$libdir", NULL, NULL
  	},
  
  	{
  		{"krb_server_keyfile", PGC_POSTMASTER, CONN_AUTH_SECURITY,
  			gettext_noop("Sets the location of the Kerberos server key file."),
  			NULL,
  			GUC_SUPERUSER_ONLY
  		},
  		&pg_krb_server_keyfile,
  		PG_KRB_SRVTAB, NULL, NULL
  	},
  
  	{
  		{"krb_srvname", PGC_SIGHUP, CONN_AUTH_SECURITY,
  			gettext_noop("Sets the name of the Kerberos service."),
  			NULL
  		},
  		&pg_krb_srvnam,
  		PG_KRB_SRVNAM, NULL, NULL
  	},
  
  	{
  		{"bonjour_name", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
  			gettext_noop("Sets the Bonjour broadcast service name."),
  			NULL
  		},
  		&bonjour_name,
  		"", NULL, NULL
  	},
  
  	/* See main.c about why defaults for LC_foo are not all alike */
  
  	{
  		{"lc_collate", PGC_INTERNAL, CLIENT_CONN_LOCALE,
  			gettext_noop("Shows the collation order locale."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&locale_collate,
  		"C", NULL, NULL
  	},
  
  	{
  		{"lc_ctype", PGC_INTERNAL, CLIENT_CONN_LOCALE,
  			gettext_noop("Shows the character classification and case conversion locale."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&locale_ctype,
  		"C", NULL, NULL
  	},
  
  	{
  		{"lc_messages", PGC_SUSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the language in which messages are displayed."),
  			NULL
  		},
  		&locale_messages,
  		"", locale_messages_assign, NULL
  	},
  
  	{
  		{"lc_monetary", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the locale for formatting monetary amounts."),
  			NULL
  		},
  		&locale_monetary,
  		"C", locale_monetary_assign, NULL
  	},
  
  	{
  		{"lc_numeric", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the locale for formatting numbers."),
  			NULL,
  			/* Please don't remove GUC_GPDB_ADDOPT or lc_numeric won't work correctly */
  			GUC_GPDB_ADDOPT
  		},
  		&locale_numeric,
  		"C", locale_numeric_assign, NULL
  	},
  
  	{
  		{"lc_time", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the locale for formatting date and time values."),
  			NULL
  		},
  		&locale_time,
  		"C", locale_time_assign, NULL
  	},
  
  	{
  		{"shared_preload_libraries", PGC_POSTMASTER, RESOURCES_KERNEL,
  			gettext_noop("Lists shared libraries to preload into server."),
  			NULL,
  			GUC_LIST_INPUT | GUC_LIST_QUOTE | GUC_SUPERUSER_ONLY
  		},
  		&shared_preload_libraries_string,
  		"", NULL, NULL
  	},
  
  	{
  		{"local_preload_libraries", PGC_BACKEND, CLIENT_CONN_OTHER,
  			gettext_noop("Lists shared libraries to preload into each backend."),
  			NULL,
  			GUC_LIST_INPUT | GUC_LIST_QUOTE
  		},
  		&local_preload_libraries_string,
  		"", NULL, NULL
  	},
  
  	{
  		{"regex_flavor", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
  			gettext_noop("Sets the regular expression \"flavor\"."),
  			gettext_noop("This can be set to advanced, extended, or basic.")
  		},
  		&regex_flavor_string,
  		"advanced", assign_regex_flavor, NULL
  	},
  
  	{
  		{"search_path", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets the schema search order for names that are not schema-qualified."),
  			NULL,
  			GUC_LIST_INPUT | GUC_LIST_QUOTE | GUC_GPDB_ADDOPT
  		},
  		&namespace_search_path,
  		"\"$user\",public", assign_search_path, NULL
  	},
  
  	{
  		/* Can't be set in postgresql.conf */
  		{"server_encoding", PGC_INTERNAL, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the server (database) character set encoding."),
  			NULL,
  			GUC_IS_NAME | GUC_REPORT | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&server_encoding_string,
  		"SQL_ASCII", NULL, NULL
  	},
  
  	{
  		/* Can't be set in postgresql.conf */
  		{"server_version", PGC_INTERNAL, PRESET_OPTIONS,
  			gettext_noop("Shows the server version."),
  			NULL,
  			GUC_REPORT | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&server_version_string,
  		PG_VERSION, NULL, NULL
  	},
  
  	{
  		/* Not for general use --- used by SET ROLE */
  		{"role", PGC_USERSET, UNGROUPED,
  			gettext_noop("Sets the current role."),
  			NULL,
  			GUC_IS_NAME | GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_NOT_WHILE_SEC_REST
  		},
  		&role_string,
  		"none", assign_role, show_role
  	},
  
  	{
  		/* Not for general use --- used by SET SESSION AUTHORIZATION */
  		{"session_authorization", PGC_USERSET, UNGROUPED,
  			gettext_noop("Sets the session user name."),
  			NULL,
  			GUC_IS_NAME | GUC_REPORT | GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_NOT_WHILE_SEC_REST
  		},
  		&session_authorization_string,
  		NULL, assign_session_authorization, show_session_authorization
  	},
  
  	{
  		{"log_destination", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Defunct: Sets the destination for server log output."),
  			gettext_noop("Valid values are combinations of \"stderr\", "
  						 "\"syslog\", \"csvlog\", and \"eventlog\", "
  						 "depending on the platform."),
  			GUC_LIST_INPUT | GUC_NO_SHOW_ALL
  		},
  		&log_destination_string,
  		"stderr", assign_log_destination, NULL
  	},
  	{
  		{"log_directory", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Defunct: Sets the destination directory for log files."),
  			gettext_noop("Can be specified as relative to the data directory "
  						 "or as absolute path."),
  			GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL
  		},
  		&Log_directory,
  		"pg_log", assign_canonical_path, NULL
  	},
  	{
  		{"log_filename", PGC_SIGHUP, LOGGING_WHERE,
  			gettext_noop("Sets the file name pattern for log files."),
  			NULL,
  			GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&Log_filename,
  		"gpdb-%Y-%m-%d_%H%M%S.csv", NULL, NULL
  	},
  
  #ifdef HAVE_SYSLOG
  	{
  		{"syslog_facility", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Sets the syslog \"facility\" to be used when syslog enabled."),
  			gettext_noop("Valid values are LOCAL0, LOCAL1, LOCAL2, LOCAL3, "
  						 "LOCAL4, LOCAL5, LOCAL6, LOCAL7."),
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&syslog_facility_str,
  		"LOCAL0", assign_syslog_facility, NULL
  	},
  	{
  		{"syslog_ident", PGC_SIGHUP, DEFUNCT_OPTIONS,
  			gettext_noop("Sets the program name used to identify PostgreSQL "
  						 "messages in syslog."),
  			NULL,
  			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&syslog_ident_str,
  		"postgres", assign_syslog_ident, NULL
  	},
  #endif
  
  	{
  		{"TimeZone", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets the time zone for displaying and interpreting time stamps."),
  			NULL,
  			GUC_REPORT | GUC_GPDB_ADDOPT
  		},
  		&timezone_string,
  		"UNKNOWN", assign_timezone, show_timezone
  	},
  	{
  		{"timezone_abbreviations", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Selects a file of time zone abbreviations."),
  			NULL,
  		},
  		&timezone_abbreviations_string,
  		"UNKNOWN", assign_timezone_abbreviations, NULL
  	},
  
  	{
  		{"transaction_isolation", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets the current transaction's isolation level."),
  			NULL,
  			GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
  		},
  		&XactIsoLevel_string,
  		NULL, assign_XactIsoLevel, show_XactIsoLevel
  	},
  
  	{
  		{"unix_socket_group", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
  			gettext_noop("Sets the owning group of the Unix-domain socket."),
  			gettext_noop("The owning user of the socket is always the user "
  						 "that starts the server.")
  		},
  		&Unix_socket_group,
  		"", NULL, NULL
  	},
  
  	{
  		{"unix_socket_directory", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
  			gettext_noop("Sets the directory where the Unix-domain socket will be created."),
  			NULL,
  			GUC_SUPERUSER_ONLY
  		},
  		&UnixSocketDir,
  		"", assign_canonical_path, NULL
  	},
  
  	{
  		{"listen_addresses", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
  			gettext_noop("Sets the host name or IP address(es) to listen to."),
  			NULL,
  			GUC_LIST_INPUT
  		},
  		&ListenAddresses,
  		"localhost", NULL, NULL
  	},
  
  	{
  		{"wal_sync_method", PGC_SIGHUP, WAL_SETTINGS,
  			gettext_noop("Selects the method used for forcing WAL updates to disk."),
  			NULL,
  			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL | GUC_DISALLOW_USER_SET
  		},
  		&XLOG_sync_method,
  		XLOG_sync_method_default, assign_xlog_sync_method, NULL
  	},
  
  	{
  		{"custom_variable_classes", PGC_SIGHUP, CUSTOM_OPTIONS,
  			gettext_noop("Sets the list of known custom variable classes."),
  			NULL,
  			GUC_LIST_INPUT | GUC_LIST_QUOTE
  		},
  		&custom_variable_classes,
  		NULL, assign_custom_variable_classes, NULL
  	},
  
  	{
  		{"data_directory", PGC_POSTMASTER, FILE_LOCATIONS,
  			gettext_noop("Sets the server's data directory."),
  			NULL,
  			GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&data_directory,
  		NULL, NULL, NULL
  	},
  
  	{
  		{"config_file", PGC_POSTMASTER, FILE_LOCATIONS,
  			gettext_noop("Sets the server's main configuration file."),
  			NULL,
  			GUC_DISALLOW_IN_FILE | GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&ConfigFileName,
  		NULL, NULL, NULL
  	},
  
  	{
  		{"hba_file", PGC_POSTMASTER, FILE_LOCATIONS,
  			gettext_noop("Sets the server's \"hba\" configuration file."),
  			NULL,
  			GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&HbaFileName,
  		NULL, NULL, NULL
  	},
  
  	{
  		{"ident_file", PGC_POSTMASTER, FILE_LOCATIONS,
  			gettext_noop("Sets the server's \"ident\" configuration file."),
  			NULL,
  			GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&IdentFileName,
  		NULL, NULL, NULL
  	},
  
  	{
  		{"xmlbinary", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets how binary values are to be encoded in XML."),
  			gettext_noop("Valid values are BASE64 and HEX.")
  		},
  		&xmlbinary_string,
  		"base64", assign_xmlbinary, NULL
  	},
  
  	{
  		{"xmloption", PGC_USERSET, CLIENT_CONN_STATEMENT,
  			gettext_noop("Sets whether XML data in implicit parsing and serialization "
  						 "operations is to be considered as documents or content fragments."),
  			gettext_noop("Valid values are DOCUMENT and CONTENT.")
  		},
  		&xmloption_string,
  		"content", assign_xmloption, NULL
  	},
  
  	{
  		{"stats_temp_directory", PGC_SIGHUP, STATS_COLLECTOR,
  			gettext_noop("Writes temporary statistics files to the specified directory."),
  			NULL,
  			GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&pgstat_temp_directory,
  		"pg_stat_tmp", assign_pgstat_temp_directory, NULL
  	},
  
  	{
  		{"default_text_search_config", PGC_USERSET, CLIENT_CONN_LOCALE,
  			gettext_noop("Sets default text search configuration."),
  			NULL
  		},
  		&TSCurrentConfig,
  		"pg_catalog.simple", assignTSCurrentConfig, NULL
  	},
  
  #ifdef USE_SSL
  	{
  		{"ssl_ciphers", PGC_POSTMASTER, CONN_AUTH_SECURITY,
  			gettext_noop("Sets the list of allowed SSL ciphers."),
  			NULL,
  			GUC_SUPERUSER_ONLY
  		},
  		&SSLCipherSuites,
  		"ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH", NULL, NULL
  	},
  #endif   /* USE_SSL */
  
  	{
  		{"application_name", PGC_USERSET, LOGGING_WHAT,
  			gettext_noop("Sets the application name to be reported in statistics and logs."),
  			NULL,
  			GUC_IS_NAME | GUC_REPORT | GUC_NOT_IN_SAMPLE
  		},
  		&application_name,
  		"", assign_application_name, NULL
  	},
  
  	{
  		{"external_pid_file", PGC_POSTMASTER, FILE_LOCATIONS,
  			gettext_noop("Writes the postmaster PID to the specified file."),
  			NULL,
  			GUC_SUPERUSER_ONLY | GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
  		},
  		&external_pid_file,
  		NULL, assign_canonical_path, NULL
  	},
  			
  	/* End-of-list marker */
  	{
  		{NULL, 0, 0, NULL, NULL}, NULL, NULL, NULL, NULL
  	}
  };
  
  
  /******** end of options list ********/
  
  
  /*
   * To allow continued support of obsolete names for GUC variables, we apply
   * the following mappings to any unrecognized name.  Note that an old name
   * should be mapped to a new one only if the new variable has very similar
   * semantics to the old.
   */
  static const char *const map_old_guc_names[] = {
  	"sort_mem", "work_mem",
  	"vacuum_mem", "maintenance_work_mem",
  	NULL
  };
  
  
  /*
   * Actual lookup of variables is done through this single, sorted array.
   */
  static struct config_generic **guc_variables;
  
  /* Current number of variables contained in the vector */
  static int	num_guc_variables;
  
  /* Vector capacity */
  static int	size_guc_variables;
  
  
  static bool guc_dirty;			/* TRUE if need to do commit/abort work */
  
  static bool reporting_enabled;	/* TRUE to enable GUC_REPORT */
  
  static int	GUCNestLevel = 0;	/* 1 when in main transaction */
  
  
  static int	guc_var_compare(const void *a, const void *b);
  static int	guc_name_compare(const char *namea, const char *nameb);
  static void push_old_value(struct config_generic * gconf, GucAction action);
  static void ReportGUCOption(struct config_generic * record);
  static void ShowGUCConfigOption(const char *name, DestReceiver *dest);
  static void ShowAllGUCConfig(DestReceiver *dest);
  static char *_ShowOption(struct config_generic * record, bool use_units);
  static bool is_newvalue_equal(struct config_generic * record, const char *newvalue);
  
  
  /*
   * Some infrastructure for checking malloc/strdup/realloc calls
   */
  static void *
  guc_malloc(int elevel, size_t size)
  {
  	void	   *data;
  
  	data = malloc(size);
  	if (data == NULL)
  		ereport(elevel,
  				(errcode(ERRCODE_OUT_OF_MEMORY),
  				 errmsg("out of memory")));
  	return data;
  }
  
  static void *
  guc_realloc(int elevel, void *old, size_t size)
  {
  	void	   *data;
  
  	data = realloc(old, size);
  	if (data == NULL)
  		ereport(elevel,
  				(errcode(ERRCODE_OUT_OF_MEMORY),
  				 errmsg("out of memory")));
  	return data;
  }
  
  static char *
  guc_strdup(int elevel, const char *src)
  {
  	char	   *data;
  
  	data = strdup(src);
  	if (data == NULL)
  		ereport(elevel,
  				(errcode(ERRCODE_OUT_OF_MEMORY),
  				 errmsg("out of memory")));
  	return data;
  }
  
  
  /*
   * Support for assigning to a field of a string GUC item.  Free the prior
   * value if it's not referenced anywhere else in the item (including stacked
   * states).
   */
  static void
  set_string_field(struct config_string * conf, char **field, char *newval)
  {
  	char	   *oldval = *field;
  	GucStack   *stack;
  
  	/* Do the assignment */
  	*field = newval;
  
  	/* Exit if any duplicate references, or if old value was NULL anyway */
  	if (oldval == NULL ||
  		oldval == *(conf->variable) ||
  		oldval == conf->reset_val ||
  		oldval == conf->boot_val)
  		return;
  	for (stack = conf->gen.stack; stack; stack = stack->prev)
  	{
  		if (oldval == stack->prior.stringval ||
  			oldval == stack->masked.stringval)
  			return;
  	}
  
  	/* Not used anymore, so free it */
  	free(oldval);
  }
  
  /*
   * Detect whether strval is referenced anywhere in a GUC string item
   */
  static bool
  string_field_used(struct config_string * conf, char *strval)
  {
  	GucStack   *stack;
  
  	if (strval == *(conf->variable) ||
  		strval == conf->reset_val ||
  		strval == conf->boot_val)
  		return true;
  	for (stack = conf->gen.stack; stack; stack = stack->prev)
  	{
  		if (strval == stack->prior.stringval ||
  			strval == stack->masked.stringval)
  			return true;
  	}
  	return false;
  }
  
  /*
   * Support for copying a variable's active value into a stack entry
   */
  static void
  set_stack_value(struct config_generic * gconf, union config_var_value * val)
  {
  	switch (gconf->vartype)
  	{
  		case PGC_BOOL:
  			val->boolval =
  				*((struct config_bool *) gconf)->variable;
  			break;
  		case PGC_INT:
  			val->intval =
  				*((struct config_int *) gconf)->variable;
  			break;
  		case PGC_REAL:
  			val->realval =
  				*((struct config_real *) gconf)->variable;
  			break;
  		case PGC_STRING:
  			/* we assume stringval is NULL if not valid */
  			set_string_field((struct config_string *) gconf,
  							 &(val->stringval),
  							 *((struct config_string *) gconf)->variable);
  			break;
  	}
  }
  
  /*
   * Support for discarding a no-longer-needed value in a stack entry
   */
  static void
  discard_stack_value(struct config_generic * gconf, union config_var_value * val)
  {
  	switch (gconf->vartype)
  	{
  		case PGC_BOOL:
  		case PGC_INT:
  		case PGC_REAL:
  			/* no need to do anything */
  			break;
  		case PGC_STRING:
  			set_string_field((struct config_string *) gconf,
  							 &(val->stringval),
  							 NULL);
  			break;
  	}
  }
  
  
  /*
   * Fetch the sorted array pointer (exported for help_config.c's use ONLY)
   */
  struct config_generic **
  get_guc_variables(void)
  {
  	return guc_variables;
  }
  int get_num_guc_variables(void)
  {
  	return num_guc_variables;
  }
  
  
  /*
   * gp_guc_list_init
   *
   * Builds global lists of interesting GUCs for use with gp_guc_list_show()...
   *
   * - gp_guc_list_for_explain: consists of planner GUCs, plus 'work_mem'
   * - gp_guc_list_for_no_plan: planner method enables for cdb_no_plan_for_query().
   */
  static void
  gp_guc_list_init(void)
  {
      int         i;
  
      if (gp_guc_list_for_explain)
      {
          list_free(gp_guc_list_for_explain);
          gp_guc_list_for_explain = NIL;
      }
      if (gp_guc_list_for_no_plan)
      {
          list_free(gp_guc_list_for_no_plan);
          gp_guc_list_for_no_plan = NIL;
      }
  
  	for (i = 0; i < num_guc_variables; i++)
  	{
  		struct config_generic  *gconf = guc_variables[i];
          bool    explain = false;
          bool    no_plan = false;
  
          switch (gconf->group)
          {
              case QUERY_TUNING:
              case QUERY_TUNING_COST:
              case QUERY_TUNING_OTHER:
                  explain = true;
                  break;
  
              case QUERY_TUNING_METHOD:
                  explain = true;
                  no_plan = true;
                  break;
  
              case RESOURCES_MEM:
                  if (0 == guc_name_compare(gconf->name, "work_mem"))
                      explain = true;
                  break;
  
              default:
                  break;
          }
  
          if (explain)
              gp_guc_list_for_explain = lappend(gp_guc_list_for_explain, gconf);
          if (no_plan)
              gp_guc_list_for_no_plan = lappend(gp_guc_list_for_no_plan, gconf);
  	}
  }                               /* gp_guc_list_init */
  
  
  /*
   * gp_guc_list_show
   *
   * Given a list of GUCs (a List of struct config_generic), appends the
   * option names and values to caller's buffer, skipping any whose
   * source <= 'excluding'.  The 'pfx' string is inserted at the
   * beginning.  The 'fmt' string must contain two occurrences of "%s",
   * which are expanded to the GUC name and value, respectively.
   *
   * Returns the length of the string appended to the buffer.
   */
  int
  gp_guc_list_show(struct StringInfoData    *buf,
                    const char               *pfx,
                    const char               *fmt,
                    GucSource                 excluding,
                    List                     *guclist)
  {
      int         oldlen = buf->len;
      ListCell   *cell;
      char       *value;
      struct config_generic  *gconf;
  
  	foreach(cell, guclist)
  	{
  		gconf = (struct config_generic *)lfirst(cell);
  		if (gconf->source > excluding)
          {
              if (pfx)
              {
                  appendStringInfoString(buf, pfx);
                  pfx = NULL;
              }
              value = _ShowOption(gconf, true);
              appendStringInfo(buf, fmt, gconf->name, value);
              pfree(value);
          }
  	}
      return buf->len - oldlen;
  }                               /* gp_guc_list_show */
  
  
  /*
   * Build the sorted array.	This is split out so that it could be
   * re-executed after startup (eg, we could allow loadable modules to
   * add vars, and then we'd need to re-sort).
   */
  void
  build_guc_variables(void)
  {
  	int			size_vars;
  	int			num_vars = 0;
  	struct config_generic **guc_vars;
  	int			i;
  
  	/* validate that the config_group array has same # of elements as config_group enumeration */
  	for ( i = 0; i < ___CONFIG_GROUP_COUNT; i++)
  	{
  	    Assert(config_group_names[i] != NULL);
  	}
  	Assert(config_group_names[___CONFIG_GROUP_COUNT] == NULL);
  
  	for (i = 0; ConfigureNamesBool[i].gen.name; i++)
  	{
  		struct config_bool *conf = &ConfigureNamesBool[i];
  
  		/* Rather than requiring vartype to be filled in by hand, do this: */
  		conf->gen.vartype = PGC_BOOL;
  		num_vars++;
  	}
  
  	for (i = 0; ConfigureNamesBool_gp[i].gen.name; i++)
  	{
  		struct config_bool *conf = &ConfigureNamesBool_gp[i];
  
  		conf->gen.vartype = PGC_BOOL;
  		num_vars++;
  	}
  
  	for (i = 0; ConfigureNamesInt[i].gen.name; i++)
  	{
  		struct config_int *conf = &ConfigureNamesInt[i];
  
  		conf->gen.vartype = PGC_INT;
  		num_vars++;
  	}
  
  	for (i = 0; ConfigureNamesInt_gp[i].gen.name; i++)
  	{
  		struct config_int *conf = &ConfigureNamesInt_gp[i];
  
  		conf->gen.vartype = PGC_INT;
  		num_vars++;
  	}
  
  	for (i = 0; ConfigureNamesReal[i].gen.name; i++)
  	{
  		struct config_real *conf = &ConfigureNamesReal[i];
  
  		conf->gen.vartype = PGC_REAL;
  		num_vars++;
  	}
  
  	for (i = 0; ConfigureNamesReal_gp[i].gen.name; i++)
  	{
  		struct config_real *conf = &ConfigureNamesReal_gp[i];
  
  		conf->gen.vartype = PGC_REAL;
  		num_vars++;
  	}
  
  	for (i = 0; ConfigureNamesString[i].gen.name; i++)
  	{
  		struct config_string *conf = &ConfigureNamesString[i];
  
  		conf->gen.vartype = PGC_STRING;
  		num_vars++;
  	}
  
  	for (i = 0; ConfigureNamesString_gp[i].gen.name; i++)
  	{
  		struct config_string *conf = &ConfigureNamesString_gp[i];
  
  		conf->gen.vartype = PGC_STRING;
  		num_vars++;
  	}
  
  	/*
  	 * Create table with 20% slack
  	 */
  	size_vars = num_vars + num_vars / 4;
  
  	guc_vars = (struct config_generic **)
  		guc_malloc(FATAL, size_vars * sizeof(struct config_generic *));
  
  	num_vars = 0;
  
  	for (i = 0; ConfigureNamesBool[i].gen.name; i++)
  		guc_vars[num_vars++] = &ConfigureNamesBool[i].gen;
  
  	for (i = 0; ConfigureNamesBool_gp[i].gen.name; i++)
  		guc_vars[num_vars++] = &ConfigureNamesBool_gp[i].gen;
  
  	for (i = 0; ConfigureNamesInt[i].gen.name; i++)
  		guc_vars[num_vars++] = &ConfigureNamesInt[i].gen;
  
  	for (i = 0; ConfigureNamesInt_gp[i].gen.name; i++)
  		guc_vars[num_vars++] = &ConfigureNamesInt_gp[i].gen;
  
  	for (i = 0; ConfigureNamesReal[i].gen.name; i++)
  		guc_vars[num_vars++] = &ConfigureNamesReal[i].gen;
  
  	for (i = 0; ConfigureNamesReal_gp[i].gen.name; i++)
  		guc_vars[num_vars++] = &ConfigureNamesReal_gp[i].gen;
  
  	for (i = 0; ConfigureNamesString[i].gen.name; i++)
  		guc_vars[num_vars++] = &ConfigureNamesString[i].gen;
  
  	for (i = 0; ConfigureNamesString_gp[i].gen.name; i++)
  		guc_vars[num_vars++] = &ConfigureNamesString_gp[i].gen;
  
  	if (guc_variables)
  		free(guc_variables);
  	guc_variables = guc_vars;
  	num_guc_variables = num_vars;
  	size_guc_variables = size_vars;
  	qsort((void *) guc_variables, num_guc_variables,
  		  sizeof(struct config_generic *), guc_var_compare);
  }
  
  /*
   * Add a new GUC variable to the list of known variables. The
   * list is expanded if needed.
   */
  static bool
  add_guc_variable(struct config_generic * var, int elevel)
  {
  	if (num_guc_variables + 1 >= size_guc_variables)
  	{
  		/*
  		 * Increase the vector by 25%
  		 */
  		int			size_vars = size_guc_variables + size_guc_variables / 4;
  		struct config_generic **guc_vars;
  
  		if (size_vars == 0)
  		{
  			size_vars = 100;
  			guc_vars = (struct config_generic **)
  				guc_malloc(elevel, size_vars * sizeof(struct config_generic *));
  		}
  		else
  		{
  			guc_vars = (struct config_generic **)
  				guc_realloc(elevel, guc_variables, size_vars * sizeof(struct config_generic *));
  		}
  
  		if (guc_vars == NULL)
  			return false;		/* out of memory */
  
  		guc_variables = guc_vars;
  		size_guc_variables = size_vars;
  	}
  	guc_variables[num_guc_variables++] = var;
  	qsort((void *) guc_variables, num_guc_variables,
  		  sizeof(struct config_generic *), guc_var_compare);
  	return true;
  }
  
  /*
   * Create and add a placeholder variable. It's presumed to belong
   * to a valid custom variable class at this point.
   */
  static struct config_generic *
  add_placeholder_variable(const char *name, int elevel)
  {
  	size_t		sz = sizeof(struct config_string) + sizeof(char *);
  	struct config_string *var;
  	struct config_generic *gen;
  
  	var = (struct config_string *) guc_malloc(elevel, sz);
  	if (var == NULL)
  		return NULL;
  	memset(var, 0, sz);
  	gen = &var->gen;
  
  	gen->name = guc_strdup(elevel, name);
  	if (gen->name == NULL)
  	{
  		free(var);
  		return NULL;
  	}
  
  	gen->context = PGC_USERSET;
  	gen->group = CUSTOM_OPTIONS;
  	gen->short_desc = "GUC placeholder variable";
  	gen->flags = GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE | GUC_CUSTOM_PLACEHOLDER;
  	gen->vartype = PGC_STRING;
  
  	/*
  	 * The char* is allocated at the end of the struct since we have no
  	 * 'static' place to point to.	Note that the current value, as well as
  	 * the boot and reset values, start out NULL.
  	 */
  	var->variable = (char **) (var + 1);
  
  	if (!add_guc_variable((struct config_generic *) var, elevel))
  	{
  		free((void *) gen->name);
  		free(var);
  		return NULL;
  	}
  
  	return gen;
  }
  
  /*
   * Detect whether the portion of "name" before dotPos matches any custom
   * variable class name listed in custom_var_classes.  The latter must be
   * formatted the way that assign_custom_variable_classes does it, ie,
   * no whitespace.  NULL is valid for custom_var_classes.
   */
  static bool
  is_custom_class(const char *name, int dotPos, const char *custom_var_classes)
  {
  	bool		result = false;
  	const char *ccs = custom_var_classes;
  
  	if (ccs != NULL)
  	{
  		const char *start = ccs;
  
  		for (;; ++ccs)
  		{
  			char		c = *ccs;
  
  			if (c == '\0' || c == ',')
  			{
  				if (dotPos == ccs - start && strncmp(start, name, dotPos) == 0)
  				{
  					result = true;
  					break;
  				}
  				if (c == '\0')
  					break;
  				start = ccs + 1;
  			}
  		}
  	}
  	return result;
  }
  
  /*
   * Look up option NAME.  If it exists, return a pointer to its record,
   * else return NULL.  If create_placeholders is TRUE, we'll create a
   * placeholder record for a valid-looking custom variable name.
   */
  static struct config_generic *
  find_option(const char *name, bool create_placeholders, int elevel)
  {
  	const char **key = &name;
  	struct config_generic **res;
  	int			i;
  
  	Assert(name);
  
  	/*
  	 * By equating const char ** with struct config_generic *, we are assuming
  	 * the name field is first in config_generic.
  	 */
  	res = (struct config_generic **) bsearch((void *) &key,
  											 (void *) guc_variables,
  											 num_guc_variables,
  											 sizeof(struct config_generic *),
  											 guc_var_compare);
  	if (res)
  		return *res;
  
  	/*
  	 * See if the name is an obsolete name for a variable.	We assume that the
  	 * set of supported old names is short enough that a brute-force search is
  	 * the best way.
  	 */
  	for (i = 0; map_old_guc_names[i] != NULL; i += 2)
  	{
  		if (guc_name_compare(name, map_old_guc_names[i]) == 0)
  			return find_option(map_old_guc_names[i + 1], false, elevel);
  	}
  
  	if (create_placeholders)
  	{
  		/*
  		 * Check if the name is qualified, and if so, check if the qualifier
  		 * matches any custom variable class.  If so, add a placeholder.
  		 */
  		const char *dot = strchr(name, GUC_QUALIFIER_SEPARATOR);
  
  		if (dot != NULL &&
  			is_custom_class(name, dot - name, custom_variable_classes))
  			return add_placeholder_variable(name, elevel);
  	}
  
  	/* Unknown name */
  	return NULL;
  }
  
  
  /*
   * comparator for qsorting and bsearching guc_variables array
   */
  static int
  guc_var_compare(const void *a, const void *b)
  {
  	struct config_generic *confa = *(struct config_generic **) a;
  	struct config_generic *confb = *(struct config_generic **) b;
  
  	return guc_name_compare(confa->name, confb->name);
  }
  
  /*
   * the bare comparison function for GUC names
   */
  static int
  guc_name_compare(const char *namea, const char *nameb)
  {
  	/*
  	 * The temptation to use strcasecmp() here must be resisted, because the
  	 * array ordering has to remain stable across setlocale() calls. So, build
  	 * our own with a simple ASCII-only downcasing.
  	 */
  	while (*namea && *nameb)
  	{
  		char		cha = *namea++;
  		char		chb = *nameb++;
  
  		if (cha >= 'A' && cha <= 'Z')
  			cha += 'a' - 'A';
  		if (chb >= 'A' && chb <= 'Z')
  			chb += 'a' - 'A';
  		if (cha != chb)
  			return cha - chb;
  	}
  	if (*namea)
  		return 1;				/* a is longer */
  	if (*nameb)
  		return -1;				/* b is longer */
  	return 0;
  }
  
  
  /*
   * Initialize GUC options during program startup.
   *
   * Note that we cannot read the config file yet, since we have not yet
   * processed command-line switches.
   */
  void
  InitializeGUCOptions(void)
  {
  	int			i;
  	char	   *env;
  	long		stack_rlimit;
  	/*
  	 * Before log_line_prefix could possibly receive a nonempty setting, make
  	 * sure that timezone processing is minimally alive (see elog.c).
  	 */
  	pg_timezone_pre_initialize();
  
  	/*
  	 * Before log_line_prefix could possibly receive a nonempty setting, make
  	 * sure that timezone processing is minimally alive (see elog.c).
  	 */
  	pg_timezone_pre_initialize();
  
  	/*
  	 * Build sorted array of all GUC variables.
  	 */
  	build_guc_variables();
  
  	/*
  	 * Load all variables with their compiled-in defaults, and initialize
  	 * status fields as needed.
  	 */
  	for (i = 0; i < num_guc_variables; i++)
  	{
  		struct config_generic *gconf = guc_variables[i];
  
  		gconf->status = 0;
  		gconf->reset_source = PGC_S_DEFAULT;
  		gconf->source = PGC_S_DEFAULT;
  		gconf->stack = NULL;
  
  		switch (gconf->vartype)
  		{
  			case PGC_BOOL:
  				{
  					struct config_bool *conf = (struct config_bool *) gconf;
  
  					if (conf->assign_hook)
  						if (!(*conf->assign_hook) (conf->boot_val, true,
  												   PGC_S_DEFAULT))
  							elog(FATAL, "failed to initialize %s to %d",
  								 conf->gen.name, (int) conf->boot_val);
  					*conf->variable = conf->reset_val = conf->boot_val;
  					break;
  				}
  			case PGC_INT:
  				{
  					struct config_int *conf = (struct config_int *) gconf;
  
  					Assert(conf->boot_val >= conf->min);
  					Assert(conf->boot_val <= conf->max);
  					if (conf->assign_hook)
  						if (!(*conf->assign_hook) (conf->boot_val, true,
  												   PGC_S_DEFAULT))
  							elog(FATAL, "failed to initialize %s to %d",
  								 conf->gen.name, conf->boot_val);
  					*conf->variable = conf->reset_val = conf->boot_val;
  					break;
  				}
  			case PGC_REAL:
  				{
  					struct config_real *conf = (struct config_real *) gconf;
  
  					Assert(conf->boot_val >= conf->min);
  					Assert(conf->boot_val <= conf->max);
  					if (conf->assign_hook)
  						if (!(*conf->assign_hook) (conf->boot_val, true,
  												   PGC_S_DEFAULT))
  							elog(FATAL, "failed to initialize %s to %g",
  								 conf->gen.name, conf->boot_val);
  					*conf->variable = conf->reset_val = conf->boot_val;
  					break;
  				}
  			case PGC_STRING:
  				{
  					struct config_string *conf = (struct config_string *) gconf;
  					char	   *str;
  
  					*conf->variable = NULL;
  					conf->reset_val = NULL;
  
  					if (conf->boot_val == NULL)
  					{
  						/* leave the value NULL, do not call assign hook */
  						break;
  					}
  
  					str = guc_strdup(FATAL, conf->boot_val);
  					conf->reset_val = str;
  
  					if (conf->assign_hook)
  					{
  						const char *newstr;
  
  						newstr = (*conf->assign_hook) (str, true,
  													   PGC_S_DEFAULT);
  						if (newstr == NULL)
  						{
  							elog(FATAL, "failed to initialize %s to \"%s\"",
  								 conf->gen.name, str);
  						}
  						else if (newstr != str)
  						{
  							free(str);
  
  							/*
  							 * See notes in set_config_option about casting
  							 */
  							str = (char *) newstr;
  							conf->reset_val = str;
  						}
  					}
  					*conf->variable = str;
  					break;
  				}
  		}
  	}
  
  	guc_dirty = false;
  
  	reporting_enabled = false;
  
  	/*
  	 * Prevent any attempt to override the transaction modes from
  	 * non-interactive sources.
  	 */
  	SetConfigOption("transaction_isolation", "default",
  					PGC_POSTMASTER, PGC_S_OVERRIDE);
  	SetConfigOption("transaction_read_only", "no",
  					PGC_POSTMASTER, PGC_S_OVERRIDE);
  
  	/*
  	 * For historical reasons, some GUC parameters can receive defaults from
  	 * environment variables.  Process those settings.	NB: if you add or
  	 * remove anything here, see also ProcessConfigFile().
  	 */
  
  	env = getenv("PGPORT");
  	if (env != NULL)
  		SetConfigOption("port", env, PGC_POSTMASTER, PGC_S_ENV_VAR);
  
  	env = getenv("PGDATESTYLE");
  	if (env != NULL)
  		SetConfigOption("datestyle", env, PGC_POSTMASTER, PGC_S_ENV_VAR);
  
  	env = getenv("PGCLIENTENCODING");
  	if (env != NULL)
  		SetConfigOption("client_encoding", env, PGC_POSTMASTER, PGC_S_ENV_VAR);
  
  	/*
  	 * rlimit isn't exactly an "environment variable", but it behaves about
  	 * the same.  If we can identify the platform stack depth rlimit, increase
  	 * default stack depth setting up to whatever is safe (but at most 2MB).
  	 */
  	stack_rlimit = get_stack_depth_rlimit();
  	if (stack_rlimit > 0)
  	{
  		int			new_limit = (stack_rlimit - STACK_DEPTH_SLOP) / 1024L;
  
  		if (new_limit > 100)
  		{
  			char		limbuf[16];
  
  			new_limit = Min(new_limit, 2048);
  			sprintf(limbuf, "%d", new_limit);
  			SetConfigOption("max_stack_depth", limbuf,
  							PGC_POSTMASTER, PGC_S_ENV_VAR);
  		}
  	}
  }
  
  
  /*
   * Select the configuration files and data directory to be used, and
   * do the initial read of postgresql.conf.
   *
   * This is called after processing command-line switches.
   *		userDoption is the -D switch value if any (NULL if unspecified).
   *		progname is just for use in error messages.
   *
   * Returns true on success; on failure, prints a suitable error message
   * to stderr and returns false.
   */
  bool
  SelectConfigFiles(const char *userDoption, const char *progname)
  {
  	char	   *configdir = NULL;
  	char	   *fname;
  	struct stat stat_buf;
  
  	/* configdir is -D option, or $PGDATA if no -D */
  	if (userDoption)
  		configdir = make_absolute_path(userDoption);
  	else
  		configdir = make_absolute_path(getenv("PGDATA"));
  
  	/*
  	 * Find the configuration file: if config_file was specified on the
  	 * command line, use it, else use configdir/postgresql.conf.  In any case
  	 * ensure the result is an absolute path, so that it will be interpreted
  	 * the same way by future backends.
  	 */
  	if (ConfigFileName)
  		fname = make_absolute_path(ConfigFileName);
  	else if (configdir)
  	{
  		fname = guc_malloc(FATAL,
  						   strlen(configdir) + strlen(CONFIG_FILENAME) + 2);
  		sprintf(fname, "%s/%s", configdir, CONFIG_FILENAME);
  	}
  	else
  	{
  		write_stderr("%s does not know where to find the server configuration file.\n"
  					 "You must specify the --config-file or -D invocation "
  					 "option or set the PGDATA environment variable.\n",
  					 progname);
  		return false;
  	}
  
  	/*
  	 * Set the ConfigFileName GUC variable to its final value, ensuring that
  	 * it can't be overridden later.
  	 */
  	SetConfigOption("config_file", fname, PGC_POSTMASTER, PGC_S_OVERRIDE);
  	free(fname);
  
  	/*
  	 * Now read the config file for the first time.
  	 */
  	if (stat(ConfigFileName, &stat_buf) != 0)
  	{
  		write_stderr("%s cannot access the server configuration file \"%s\": %s\n",
  					 progname, ConfigFileName, strerror(errno));
  		return false;
  	}
  
  	ProcessConfigFile(PGC_POSTMASTER);
  
  	/*
  	 * If the data_directory GUC variable has been set, use that as DataDir;
  	 * otherwise use configdir if set; else punt.
  	 *
  	 * Note: SetDataDir will copy and absolute-ize its argument, so we don't
  	 * have to.
  	 */
  	if (data_directory)
  		SetDataDir(data_directory);
  	else if (configdir)
  		SetDataDir(configdir);
  	else
  	{
  		write_stderr("%s does not know where to find the database system data.\n"
  					 "This can be specified as \"data_directory\" in \"%s\", "
  					 "or by the -D invocation option, or by the "
  					 "PGDATA environment variable.\n",
  					 progname, ConfigFileName);
  		return false;
  	}
  
  	/*
  	 * Reflect the final DataDir value back into the data_directory GUC var.
  	 * (If you are wondering why we don't just make them a single variable,
  	 * it's because the EXEC_BACKEND case needs DataDir to be transmitted to
  	 * child backends specially.  XXX is that still true?  Given that we now
  	 * chdir to DataDir, EXEC_BACKEND can read the config file without knowing
  	 * DataDir in advance.)
  	 */
  	SetConfigOption("data_directory", DataDir, PGC_POSTMASTER, PGC_S_OVERRIDE);
  
  	/*
  	 * Figure out where pg_hba.conf is, and make sure the path is absolute.
  	 */
  	if (HbaFileName)
  		fname = make_absolute_path(HbaFileName);
  	else if (configdir)
  	{
  		fname = guc_malloc(FATAL,
  						   strlen(configdir) + strlen(HBA_FILENAME) + 2);
  		sprintf(fname, "%s/%s", configdir, HBA_FILENAME);
  	}
  	else
  	{
  		write_stderr("%s does not know where to find the \"hba\" configuration file.\n"
  					 "This can be specified as \"hba_file\" in \"%s\", "
  					 "or by the -D invocation option, or by the "
  					 "PGDATA environment variable.\n",
  					 progname, ConfigFileName);
  		return false;
  	}
  	SetConfigOption("hba_file", fname, PGC_POSTMASTER, PGC_S_OVERRIDE);
  	free(fname);
  
  	/*
  	 * Likewise for pg_ident.conf.
  	 */
  	if (IdentFileName)
  		fname = make_absolute_path(IdentFileName);
  	else if (configdir)
  	{
  		fname = guc_malloc(FATAL,
  						   strlen(configdir) + strlen(IDENT_FILENAME) + 2);
  		sprintf(fname, "%s/%s", configdir, IDENT_FILENAME);
  	}
  	else
  	{
  		write_stderr("%s does not know where to find the \"ident\" configuration file.\n"
  					 "This can be specified as \"ident_file\" in \"%s\", "
  					 "or by the -D invocation option, or by the "
  					 "PGDATA environment variable.\n",
  					 progname, ConfigFileName);
  		return false;
  	}
  	SetConfigOption("ident_file", fname, PGC_POSTMASTER, PGC_S_OVERRIDE);
  	free(fname);
  
  	free(configdir);
  
  	return true;
  }
  
  
  /*
   * Reset all options to their saved default values (implements RESET ALL)
   */
  void
  ResetAllOptions(void)
  {
  	int			i;
  
  	for (i = 0; i < num_guc_variables; i++)
  	{
  		struct config_generic *gconf = guc_variables[i];
  
  		/* Don't reset non-SET-able values */
  		if (gconf->context != PGC_SUSET &&
  			gconf->context != PGC_USERSET)
  			continue;
  		/* Don't reset if special exclusion from RESET ALL */
  		if (gconf->flags & GUC_NO_RESET_ALL)
  			continue;
  		/* No need to reset if wasn't SET */
  		if (gconf->source <= PGC_S_OVERRIDE)
  			continue;
  
  		/* Save old value to support transaction abort */
  		push_old_value(gconf, GUC_ACTION_SET);
  
  		switch (gconf->vartype)
  		{
  			case PGC_BOOL:
  				{
  					struct config_bool *conf = (struct config_bool *) gconf;
  
  					if (conf->assign_hook)
  						if (!(*conf->assign_hook) (conf->reset_val, true,
  												   PGC_S_SESSION))
  							elog(ERROR, "failed to reset %s to %d",
  								 conf->gen.name, (int) conf->reset_val);
  					*conf->variable = conf->reset_val;
  					conf->gen.source = conf->gen.reset_source;
  					break;
  				}
  			case PGC_INT:
  				{
  					struct config_int *conf = (struct config_int *) gconf;
  
  					if (conf->assign_hook)
  						if (!(*conf->assign_hook) (conf->reset_val, true,
  												   PGC_S_SESSION))
  							elog(ERROR, "failed to reset %s to %d",
  								 conf->gen.name, conf->reset_val);
  					*conf->variable = conf->reset_val;
  					conf->gen.source = conf->gen.reset_source;
  					break;
  				}
  			case PGC_REAL:
  				{
  					struct config_real *conf = (struct config_real *) gconf;
  
  					if (conf->assign_hook)
  						if (!(*conf->assign_hook) (conf->reset_val, true,
  												   PGC_S_SESSION))
  							elog(ERROR, "failed to reset %s to %g",
  								 conf->gen.name, conf->reset_val);
  					*conf->variable = conf->reset_val;
  					conf->gen.source = conf->gen.reset_source;
  					break;
  				}
  			case PGC_STRING:
  				{
  					struct config_string *conf = (struct config_string *) gconf;
  					char	   *str;
  
  					/* We need not strdup here */
  					str = conf->reset_val;
  
  					if (conf->assign_hook && str)
  					{
  						const char *newstr;
  
  						newstr = (*conf->assign_hook) (str, true,
  													   PGC_S_SESSION);
  						if (newstr == NULL)
  							elog(ERROR, "failed to reset %s to \"%s\"",
  								 conf->gen.name, str);
  						else if (newstr != str)
  						{
  							/*
  							 * See notes in set_config_option about casting
  							 */
  							str = (char *) newstr;
  						}
  					}
  
  					set_string_field(conf, conf->variable, str);
  					conf->gen.source = conf->gen.reset_source;
  					break;
  				}
  		}
  
  		if (gconf->flags & GUC_REPORT)
  			ReportGUCOption(gconf);
  	}
  }
  
  
  /*
   * push_old_value
   *		Push previous state during transactional assignment to a GUC variable.
   */
  static void
  push_old_value(struct config_generic * gconf, GucAction action)
  {
  	GucStack   *stack;
  
  	/* If we're not inside a nest level, do nothing */
  	if (GUCNestLevel == 0)
  		return;
  
  	/* Do we already have a stack entry of the current nest level? */
  	stack = gconf->stack;
  	if (stack && stack->nest_level >= GUCNestLevel)
  	{
  		/* Yes, so adjust its state if necessary */
  		Assert(stack->nest_level == GUCNestLevel);
  		switch (action)
  		{
  			case GUC_ACTION_SET:
  				/* SET overrides any prior action at same nest level */
  				if (stack->state == GUC_SET_LOCAL)
  				{
  					/* must discard old masked value */
  					discard_stack_value(gconf, &stack->masked);
  				}
  				stack->state = GUC_SET;
  				break;
  			case GUC_ACTION_LOCAL:
  				if (stack->state == GUC_SET)
  				{
  					/* SET followed by SET LOCAL, remember SET's value */
  					set_stack_value(gconf, &stack->masked);
  					stack->state = GUC_SET_LOCAL;
  				}
  				/* in all other cases, no change to stack entry */
  				break;
  			case GUC_ACTION_SAVE:
  				/* Could only have a prior SAVE of same variable */
  				Assert(stack->state == GUC_SAVE);
  				break;
  		}
  		Assert(guc_dirty);		/* must be set already */
  		return;
  	}
  
  	/*
  	 * Push a new stack entry
  	 *
  	 * We keep all the stack entries in TopTransactionContext for simplicity.
  	 */
  	stack = (GucStack *) MemoryContextAllocZero(TopTransactionContext,
  												sizeof(GucStack));
  
  	stack->prev = gconf->stack;
  	stack->nest_level = GUCNestLevel;
  	switch (action)
  	{
  		case GUC_ACTION_SET:
  			stack->state = GUC_SET;
  			break;
  		case GUC_ACTION_LOCAL:
  			stack->state = GUC_LOCAL;
  			break;
  		case GUC_ACTION_SAVE:
  			stack->state = GUC_SAVE;
  			break;
  	}
  	stack->source = gconf->source;
  	set_stack_value(gconf, &stack->prior);
  
  	gconf->stack = stack;
  
  	/* Ensure we remember to pop at end of xact */
  	guc_dirty = true;
  }
  
  
  /*
   * Do GUC processing at main transaction start.
   */
  void
  AtStart_GUC(void)
  {
  	/*
  	 * The nest level should be 0 between transactions; if it isn't, somebody
  	 * didn't call AtEOXact_GUC, or called it with the wrong nestLevel.  We
  	 * throw a warning but make no other effort to clean up.
  	 */
  	if (GUCNestLevel != 0)
  		elog(WARNING, "GUC nest level = %d at transaction start",
  			 GUCNestLevel);
  	GUCNestLevel = 1;
  }
  
  /*
   * Enter a new nesting level for GUC values.  This is called at subtransaction
   * start and when entering a function that has proconfig settings.	NOTE that
   * we must not risk error here, else subtransaction start will be unhappy.
   */
  int
  NewGUCNestLevel(void)
  {
  	return ++GUCNestLevel;
  }
  
  /*
   * Do GUC processing at transaction or subtransaction commit or abort, or
   * when exiting a function that has proconfig settings.  (The name is thus
   * a bit of a misnomer; perhaps it should be ExitGUCNestLevel or some such.)
   * During abort, we discard all GUC settings that were applied at nesting
   * levels >= nestLevel.  nestLevel == 1 corresponds to the main transaction.
   */
  void
  AtEOXact_GUC(bool isCommit, int nestLevel)
  {
  	bool		still_dirty;
  	int			i;
  
  	/*
  	 * Note: it's possible to get here with GUCNestLevel == nestLevel-1 during
  	 * abort, if there is a failure during transaction start before
  	 * AtStart_GUC is called.
  	 */
  	Assert(nestLevel > 0 &&
  		   (nestLevel <= GUCNestLevel ||
  			(nestLevel == GUCNestLevel + 1 && !isCommit)));
  
  	/* Quick exit if nothing's changed in this transaction */
  	if (!guc_dirty)
  	{
  		GUCNestLevel = nestLevel - 1;
  		return;
  	}
  
  	still_dirty = false;
  	for (i = 0; i < num_guc_variables; i++)
  	{
  		struct config_generic *gconf = guc_variables[i];
  		GucStack   *stack;
  
  		/*
  		 * Process and pop each stack entry within the nest level.	To
  		 * simplify fmgr_security_definer(), we allow failure exit from a
  		 * function-with-SET-options to be recovered at the surrounding
  		 * transaction or subtransaction abort; so there could be more than
  		 * one stack entry to pop.
  		 */
  		while ((stack = gconf->stack) != NULL &&
  			   stack->nest_level >= nestLevel)
  		{
  			GucStack   *prev = stack->prev;
  			bool		restorePrior = false;
  			bool		restoreMasked = false;
  			bool		changed;
  
  			/*
  			 * In this next bit, if we don't set either restorePrior or
  			 * restoreMasked, we must "discard" any unwanted fields of the
  			 * stack entries to avoid leaking memory.  If we do set one of
  			 * those flags, unused fields will be cleaned up after restoring.
  			 */
  			if (!isCommit)		/* if abort, always restore prior value */
  				restorePrior = true;
  			else if (stack->state == GUC_SAVE)
  				restorePrior = true;
  			else if (stack->nest_level == 1)
  			{
  				/* transaction commit */
  				if (stack->state == GUC_SET_LOCAL)
  					restoreMasked = true;
  				else if (stack->state == GUC_SET)
  				{
  					/* we keep the current active value */
  					discard_stack_value(gconf, &stack->prior);
  				}
  				else	/* must be GUC_LOCAL */
  					restorePrior = true;
  			}
  			else if (prev == NULL ||
  					 prev->nest_level < stack->nest_level - 1)
  			{
  				/* decrement entry's level and do not pop it */
  				stack->nest_level--;
  				continue;
  			}
  			else
  			{
  				/*
  				 * We have to merge this stack entry into prev. See README for
  				 * discussion of this bit.
  				 */
  				switch (stack->state)
  				{
  					case GUC_SAVE:
  						Assert(false);	/* can't get here */
  
  					case GUC_SET:
  						/* next level always becomes SET */
  						discard_stack_value(gconf, &stack->prior);
  						if (prev->state == GUC_SET_LOCAL)
  							discard_stack_value(gconf, &prev->masked);
  						prev->state = GUC_SET;
  						break;
  
  					case GUC_LOCAL:
  						if (prev->state == GUC_SET)
  						{
  							/* LOCAL migrates down */
  							prev->masked = stack->prior;
  							prev->state = GUC_SET_LOCAL;
  						}
  						else
  						{
  							/* else just forget this stack level */
  							discard_stack_value(gconf, &stack->prior);
  						}
  						break;
  
  					case GUC_SET_LOCAL:
  						/* prior state at this level no longer wanted */
  						discard_stack_value(gconf, &stack->prior);
  						/* copy down the masked state */
  						if (prev->state == GUC_SET_LOCAL)
  							discard_stack_value(gconf, &prev->masked);
  						prev->masked = stack->masked;
  						prev->state = GUC_SET_LOCAL;
  						break;
  				}
  			}
  
  			changed = false;
  
  			if (restorePrior || restoreMasked)
  			{
  				/* Perform appropriate restoration of the stacked value */
  				union config_var_value newvalue;
  				GucSource	newsource;
  
  				if (restoreMasked)
  				{
  					newvalue = stack->masked;
  					newsource = PGC_S_SESSION;
  				}
  				else
  				{
  					newvalue = stack->prior;
  					newsource = stack->source;
  				}
  
  				switch (gconf->vartype)
  				{
  					case PGC_BOOL:
  						{
  							struct config_bool *conf = (struct config_bool *) gconf;
  							bool		newval = newvalue.boolval;
  
  							if (*conf->variable != newval)
  							{
  								if (conf->assign_hook)
  									if (!(*conf->assign_hook) (newval,
  													   true, PGC_S_OVERRIDE))
  										elog(LOG, "failed to commit %s as %d",
  											 conf->gen.name, (int) newval);
  								*conf->variable = newval;
  								changed = true;
  							}
  							break;
  						}
  					case PGC_INT:
  						{
  							struct config_int *conf = (struct config_int *) gconf;
  							int			newval = newvalue.intval;
  
  							if (*conf->variable != newval)
  							{
  								if (conf->assign_hook)
  									if (!(*conf->assign_hook) (newval,
  													   true, PGC_S_OVERRIDE))
  										elog(LOG, "failed to commit %s as %d",
  											 conf->gen.name, newval);
  								*conf->variable = newval;
  								changed = true;
  							}
  							break;
  						}
  					case PGC_REAL:
  						{
  							struct config_real *conf = (struct config_real *) gconf;
  							double		newval = newvalue.realval;
  
  							if (*conf->variable != newval)
  							{
  								if (conf->assign_hook)
  									if (!(*conf->assign_hook) (newval,
  													   true, PGC_S_OVERRIDE))
  										elog(LOG, "failed to commit %s as %g",
  											 conf->gen.name, newval);
  								*conf->variable = newval;
  								changed = true;
  							}
  							break;
  						}
  					case PGC_STRING:
  						{
  							struct config_string *conf = (struct config_string *) gconf;
  							char	   *newval = newvalue.stringval;
  
  							if (*conf->variable != newval)
  							{
  								if (conf->assign_hook && newval)
  								{
  									const char *newstr;
  
  									newstr = (*conf->assign_hook) (newval, true,
  															 PGC_S_OVERRIDE);
  									if (newstr == NULL)
  										elog(LOG, "failed to commit %s as \"%s\"",
  											 conf->gen.name, newval);
  									else if (newstr != newval)
  									{
  										/*
  										 * If newval should now be freed,
  										 * it'll be taken care of below.
  										 *
  										 * See notes in set_config_option
  										 * about casting
  										 */
  										newval = (char *) newstr;
  									}
  								}
  
  								set_string_field(conf, conf->variable, newval);
  								changed = true;
  							}
  
  							/*
  							 * Release stacked values if not used anymore. We
  							 * could use discard_stack_value() here, but since
  							 * we have type-specific code anyway, might as
  							 * well inline it.
  							 */
  							set_string_field(conf, &stack->prior.stringval, NULL);
  							set_string_field(conf, &stack->masked.stringval, NULL);
  							break;
  						}
  				}
  
  				gconf->source = newsource;
  			}
  
  			/* Finish popping the state stack */
  			gconf->stack = prev;
  			pfree(stack);
  
  			/* Report new value if we changed it */
  			if (changed && (gconf->flags & GUC_REPORT))
  				ReportGUCOption(gconf);
  		}						/* end of stack-popping loop */
  
  		if (stack != NULL)
  			still_dirty = true;
  	}
  
  	/* If there are no remaining stack entries, we can reset guc_dirty */
  	guc_dirty = still_dirty;
  
  	/* Update nesting level */
  	GUCNestLevel = nestLevel - 1;
  }
  
  
  /*
   * Start up automatic reporting of changes to variables marked GUC_REPORT.
   * This is executed at completion of backend startup.
   */
  void
  BeginReportingGUCOptions(void)
  {
  	int			i;
  
      /* Build global lists of GUCs for use by callers of gp_guc_list_show(). */
      gp_guc_list_init();
  
  	/*
  	 * Don't do anything unless talking to an interactive frontend of protocol
  	 * 3.0 or later.
  	 */
  	if (whereToSendOutput != DestRemote ||
  		PG_PROTOCOL_MAJOR(FrontendProtocol) < 3)
  		return;
  
  	reporting_enabled = true;
  
  	/* Transmit initial values of interesting variables */
  	for (i = 0; i < num_guc_variables; i++)
  	{
  		struct config_generic *conf = guc_variables[i];
  
  		if (conf->flags & GUC_REPORT)
  			ReportGUCOption(conf);
  	}
  }
  
  /*
   * ReportGUCOption: if appropriate, transmit option value to frontend
   */
  static void
  ReportGUCOption(struct config_generic * record)
  {
  	if (reporting_enabled && (record->flags & GUC_REPORT))
  	{
  		char	   *val = _ShowOption(record, false);
  		StringInfoData msgbuf;
  
  		pq_beginmessage(&msgbuf, 'S');
  		pq_sendstring(&msgbuf, record->name);
  		pq_sendstring(&msgbuf, val);
  		pq_endmessage(&msgbuf);
  
  		pfree(val);
  	}
  }
  
  
  /*
   * Try to parse value as an integer.  The accepted formats are the
   * usual decimal, octal, or hexadecimal formats, optionally followed by
   * a unit name if "flags" indicates a unit is allowed.
   *
   * If the string parses okay, return true, else false.
   * If okay and result is not NULL, return the value in *result.
   * If not okay and hintmsg is not NULL, *hintmsg is set to a suitable
   *	HINT message, or NULL if no hint provided.
   */
  bool
  parse_int(const char *value, int *result, int flags, const char **hintmsg)
  {
  	int64		val;
  	char	   *endptr;
  
  	/* To suppress compiler warnings, always set output params */
  	if (result)
  		*result = 0;
  	if (hintmsg)
  		*hintmsg = NULL;
  
  	/* We assume here that int64 is at least as wide as long */
  	errno = 0;
  	val = strtol(value, &endptr, 0);
  
  	if (endptr == value)
  		return false;			/* no HINT for integer syntax error */
  
  	if (errno == ERANGE || val != (int64) ((int32) val))
  	{
  		if (hintmsg)
  			*hintmsg = gettext_noop("Value exceeds integer range.");
  		return false;
  	}
  
  	/* allow whitespace between integer and unit */
  	while (isspace((unsigned char) *endptr))
  		endptr++;
  
  	/* Handle possible unit */
  	if (*endptr != '\0')
  	{
  		/*
  		 * Note: the multiple-switch coding technique here is a bit tedious,
  		 * but seems necessary to avoid intermediate-value overflows.
  		 *
  		 * If INT64_IS_BUSTED (ie, it's really int32) we will fail to detect
  		 * overflow due to units conversion, but there are few enough such
  		 * machines that it does not seem worth trying to be smarter.
  		 */
  		if (flags & GUC_UNIT_MEMORY)
  		{
  			/* Set hint for use if no match or trailing garbage */
  			if (hintmsg)
  				*hintmsg = gettext_noop("Valid units for this parameter are \"kB\", \"MB\", and \"GB\".");
  
  #if BLCKSZ < 1024 || BLCKSZ > (1024*1024)
  #error BLCKSZ must be between 1KB and 1MB
  #endif
  #if XLOG_BLCKSZ < 1024 || XLOG_BLCKSZ > (1024*1024)
  #error XLOG_BLCKSZ must be between 1KB and 1MB
  #endif
  
  			if (strncmp(endptr, "kB", 2) == 0)
  			{
  				endptr += 2;
  				switch (flags & GUC_UNIT_MEMORY)
  				{
  					case GUC_UNIT_BLOCKS:
  						val /= (BLCKSZ / 1024);
  						break;
  					case GUC_UNIT_XBLOCKS:
  						val /= (XLOG_BLCKSZ / 1024);
  						break;
  				}
  			}
  			else if (strncmp(endptr, "MB", 2) == 0)
  			{
  				endptr += 2;
  				switch (flags & GUC_UNIT_MEMORY)
  				{
  					case GUC_UNIT_KB:
  						val *= KB_PER_MB;
  						break;
  					case GUC_UNIT_BLOCKS:
  						val *= KB_PER_MB / (BLCKSZ / 1024);
  						break;
  					case GUC_UNIT_XBLOCKS:
  						val *= KB_PER_MB / (XLOG_BLCKSZ / 1024);
  						break;
  				}
  			}
  			else if (strncmp(endptr, "GB", 2) == 0)
  			{
  				endptr += 2;
  				switch (flags & GUC_UNIT_MEMORY)
  				{
  					case GUC_UNIT_KB:
  						val *= KB_PER_GB;
  						break;
  					case GUC_UNIT_BLOCKS:
  						val *= KB_PER_GB / (BLCKSZ / 1024);
  						break;
  					case GUC_UNIT_XBLOCKS:
  						val *= KB_PER_GB / (XLOG_BLCKSZ / 1024);
  						break;
  				}
  			}
  		}
  		else if (flags & GUC_UNIT_TIME)
  		{
  			/* Set hint for use if no match or trailing garbage */
  			if (hintmsg)
  				*hintmsg = gettext_noop("Valid units for this parameter are \"ms\", \"s\", \"min\", \"h\", and \"d\".");
  
  			if (strncmp(endptr, "ms", 2) == 0)
  			{
  				endptr += 2;
  				switch (flags & GUC_UNIT_TIME)
  				{
  					case GUC_UNIT_S:
  						val /= MS_PER_S;
  						break;
  					case GUC_UNIT_MIN:
  						val /= MS_PER_MIN;
  						break;
  				}
  			}
  			else if (strncmp(endptr, "s", 1) == 0)
  			{
  				endptr += 1;
  				switch (flags & GUC_UNIT_TIME)
  				{
  					case GUC_UNIT_MS:
  						val *= MS_PER_S;
  						break;
  					case GUC_UNIT_MIN:
  						val /= S_PER_MIN;
  						break;
  				}
  			}
  			else if (strncmp(endptr, "min", 3) == 0)
  			{
  				endptr += 3;
  				switch (flags & GUC_UNIT_TIME)
  				{
  					case GUC_UNIT_MS:
  						val *= MS_PER_MIN;
  						break;
  					case GUC_UNIT_S:
  						val *= S_PER_MIN;
  						break;
  				}
  			}
  			else if (strncmp(endptr, "h", 1) == 0)
  			{
  				endptr += 1;
  				switch (flags & GUC_UNIT_TIME)
  				{
  					case GUC_UNIT_MS:
  						val *= MS_PER_H;
  						break;
  					case GUC_UNIT_S:
  						val *= S_PER_H;
  						break;
  					case GUC_UNIT_MIN:
  						val *= MIN_PER_H;
  						break;
  				}
  			}
  			else if (strncmp(endptr, "d", 1) == 0)
  			{
  				endptr += 1;
  				switch (flags & GUC_UNIT_TIME)
  				{
  					case GUC_UNIT_MS:
  						val *= MS_PER_D;
  						break;
  					case GUC_UNIT_S:
  						val *= S_PER_D;
  						break;
  					case GUC_UNIT_MIN:
  						val *= MIN_PER_D;
  						break;
  				}
  			}
  		}
  
  		/* allow whitespace after unit */
  		while (isspace((unsigned char) *endptr))
  			endptr++;
  
  		if (*endptr != '\0')
  			return false;		/* appropriate hint, if any, already set */
  
  		/* Check for overflow due to units conversion */
  		if (val != (int64) ((int32) val))
  		{
  			if (hintmsg)
  				*hintmsg = gettext_noop("Value exceeds integer range.");
  			return false;
  		}
  	}
  
  	if (result)
  		*result = (int) val;
  	return true;
  }
  
  
  
  /*
   * Try to parse value as a floating point constant in the usual
   * format.	If the value parsed okay return true, else false.  If
   * result is not NULL, return the semantic value there.
   */
  static bool
  parse_real(const char *value, double *result)
  {
  	double		val;
  	char	   *endptr;
  
  	if (result)
  		*result = 0;			/* suppress compiler warning */
  
  	errno = 0;
  	val = strtod(value, &endptr);
  	if (endptr == value || errno == ERANGE)
  		return false;
  
  	/* allow whitespace after number */
  	while (isspace((unsigned char) *endptr))
  		endptr++;
  	if (*endptr != '\0')
  		return false;
  
  	if (result)
  		*result = val;
  	return true;
  }
  
  
  /*
   * Call a GucStringAssignHook function, being careful to free the
   * "newval" string if the hook ereports.
   *
   * This is split out of set_config_option just to avoid the "volatile"
   * qualifiers that would otherwise have to be plastered all over.
   */
  static const char *
  call_string_assign_hook(GucStringAssignHook assign_hook,
  						char *newval, bool doit, GucSource source)
  {
  	const char *result = NULL;
  
  	PG_TRY();
  	{
  		result = (*assign_hook) (newval, doit, source);
  	}
  	PG_CATCH();
  	{
  		free(newval);
  		PG_RE_THROW();
  	}
  	PG_END_TRY();
  
  	return result;
  }
  
  
  /*
   * Sets option `name' to given value. The value should be a string
   * which is going to be parsed and converted to the appropriate data
   * type.  The context and source parameters indicate in which context this
   * function is being called so it can apply the access restrictions
   * properly.
   *
   * If value is NULL, set the option to its default value (normally the
   * reset_val, but if source == PGC_S_DEFAULT we instead use the boot_val).
   *
   * action indicates whether to set the value globally in the session, locally
   * to the current top transaction, or just for the duration of a function call.
   *
   * If changeVal is false then don't really set the option but do all
   * the checks to see if it would work.
   *
   * If there is an error (non-existing option, invalid value) then an
   * ereport(ERROR) is thrown *unless* this is called in a context where we
   * don't want to ereport (currently, startup or SIGHUP config file reread).
   * In that case we write a suitable error message via ereport(LOG) and
   * return false. This is working around the deficiencies in the ereport
   * mechanism, so don't blame me.  In all other cases, the function
   * returns true, including cases where the input is valid but we chose
   * not to apply it because of context or source-priority considerations.
   *
   * See also SetConfigOption for an external interface.
   */
  bool
  set_config_option(const char *name, const char *value,
  				  GucContext context, GucSource source,
  				  GucAction action, bool changeVal)
  {
  	struct config_generic *record;
  	int			elevel;
  	bool		makeDefault;
  
  	if (context == PGC_SIGHUP || context == PGC_POSTMASTER || source == PGC_S_DEFAULT)
  	{
  		/*
  		 * To avoid cluttering the log, only the postmaster bleats loudly
  		 * about problems with the config file.
  		 */
  		elevel = IsUnderPostmaster ? DEBUG3 : LOG;
  	}
  	else if (source == PGC_S_DATABASE || source == PGC_S_USER)
  		elevel = WARNING;
  	else
  		elevel = ERROR;
  
  	record = find_option(name, true, elevel);
  	if (record == NULL)
  	{
  		ereport(elevel,
  				(errcode(ERRCODE_UNDEFINED_OBJECT),
  			   errmsg("unrecognized configuration parameter \"%s\"", name),
  			   errSendAlert(false)));
  		return false;
  	}
  
          /*
           * Check if option can be set by the user.
           */
          if (record->flags & GUC_DISALLOW_USER_SET)
   	{
                /* Only print a warning in the dispatch or utility mode */
            if (changeVal)
    	          if (Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_UTILITY)
  	              elog(WARNING, "\"%s\": can not be set by the user and will be ignored.", name);
  	      return true;
          }  /* end if (record->flags & GUC_DISALLOW_USER_SET) */
  
  	/*
  	 * If source is postgresql.conf, mark the found record with
  	 * GUC_IS_IN_FILE. This is for the convenience of ProcessConfigFile.  Note
  	 * that we do it even if changeVal is false, since ProcessConfigFile wants
  	 * the marking to occur during its testing pass.
  	 */
  	if (source == PGC_S_FILE)
  		record->status |= GUC_IS_IN_FILE;
  
  	/*
  	 * Check if the option can be set at this time. See guc.h for the precise
  	 * rules. Note that we don't want to throw errors if we're in the SIGHUP
  	 * context. In that case we just ignore the attempt and return true.
  	 */
  	switch (record->context)
  	{
  		case PGC_INTERNAL:
  			if (context == PGC_SIGHUP)
  				return true;
  			if (context != PGC_INTERNAL)
  			{
  				ereport(elevel,
  						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
  						 errmsg("parameter \"%s\" cannot be changed",
  								name)));
  				return false;
  			}
  			break;
  		case PGC_POSTMASTER:
  			if (context == PGC_SIGHUP)
  			{
  				/*
  				 * We are reading a PGC_POSTMASTER var from postgresql.conf.
  				 * We can't change the setting, so give a warning if the DBA
  				 * tries to change it.	(Throwing an error would be more
  				 * consistent, but seems overly rigid.)
  				 */
  				if (changeVal && !is_newvalue_equal(record, value))
  					ereport(elevel,
  							(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
  							 errmsg("parameter \"%s\" cannot be changed after server start; configuration file change ignored",
  									name)));
  				return true;
  			}
  			if (context != PGC_POSTMASTER)
  			{
  				ereport(elevel,
  						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
  					   errmsg("attempted change of parameter \"%s\" ignored",
  							  name),
  						 errdetail("This parameter cannot be changed after server start.")));
  				return false;
  			}
  			break;
  		case PGC_SIGHUP:
  			if (context != PGC_SIGHUP && context != PGC_POSTMASTER)
  			{
  				ereport(elevel,
  						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
  						 errmsg("parameter \"%s\" cannot be changed now",
  								name)));
  				return false;
  			}
  
  			/*
  			 * Hmm, the idea of the SIGHUP context is "ought to be global, but
  			 * can be changed after postmaster start". But there's nothing
  			 * that prevents a crafty administrator from sending SIGHUP
  			 * signals to individual backends only.
  			 */
  			break;
  		case PGC_BACKEND:
  			if (context == PGC_SIGHUP)
  			{
  				/*
  				 * If a PGC_BACKEND parameter is changed in the config file,
  				 * we want to accept the new value in the postmaster (whence
  				 * it will propagate to subsequently-started backends), but
  				 * ignore it in existing backends.	This is a tad klugy, but
  				 * necessary because we don't re-read the config file during
  				 * backend start.
  				 */
  				if (IsUnderPostmaster)
  					return true;
  			}
  			else if (context != PGC_BACKEND && context != PGC_POSTMASTER &&
  					 source != PGC_S_CLIENT)
  			{
  				ereport(elevel,
  						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
  						 errmsg("parameter \"%s\" cannot be set after connection start",
  								name)));
  				return false;
  			}
  			break;
  		case PGC_SUSET:
  			if (context == PGC_USERSET || context == PGC_BACKEND)
  			{
  				ereport(elevel,
  						(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  						 errmsg("permission denied to set parameter \"%s\"",
  								name)));
  				return false;
  			}
  			break;
  		case PGC_USERSET:
  			/* always okay */
  			break;
  	}
  
  	/* Print out warnings for the attempt to set the GUC in DEPRECATED_OPTIONS. */
  	if (record->group == DEPRECATED_OPTIONS)
  	{
  		/* Only print a warning in the dispatch or utility mode */
  		if (Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_UTILITY)
  			elog(WARNING, "\"%s\": setting is deprecated, and may be removed"
  				 " in a future release.", name);
  	}
  
  	/* Ignore attempted set if the config_group is DEFUNCT_OPTIONS.*/
  	if (record->group == DEFUNCT_OPTIONS)
  	{
  		/* Only print a warning in the dispatch or utility mode */
  		if (Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_UTILITY)
  			elog(WARNING, "\"%s\": setting is ignored because it is defunct",
  				 name);
  		return true;
  	}
  
  	/*
  	 * Disallow changing GUC_NOT_WHILE_SEC_REST values if we are inside a
  	 * security restriction context.  We can reject this regardless of
  	 * the GUC context or source, mainly because sources that it might be
  	 * reasonable to override for won't be seen while inside a function.
  	 *
  	 * Note: variables marked GUC_NOT_WHILE_SEC_REST should usually be marked
  	 * GUC_NO_RESET_ALL as well, because ResetAllOptions() doesn't check this.
  	 * An exception might be made if the reset value is assumed to be "safe".
  	 *
  	 * Note: this flag is currently used for "session_authorization" and
  	 * "role".  We need to prohibit changing these inside a local userid
  	 * context because when we exit it, GUC won't be notified, leaving things
  	 * out of sync.  (This could be fixed by forcing a new GUC nesting level,
  	 * but that would change behavior in possibly-undesirable ways.)  Also,
  	 * we prohibit changing these in a security-restricted operation because
  	 * otherwise RESET could be used to regain the session user's privileges.
  	 */
  	if (record->flags & GUC_NOT_WHILE_SEC_REST)
  	{
  		if (InLocalUserIdChange())
  		{
  			/*
  			 * Phrasing of this error message is historical, but it's the
  			 * most common case.
  			 */
  			ereport(elevel,
  					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  					 errmsg("cannot set parameter \"%s\" within security-definer function",
  							name)));
  			return false;
  		}
  		if (InSecurityRestrictedOperation())
  		{
  			ereport(elevel,
  					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  					 errmsg("cannot set parameter \"%s\" within security-restricted operation",
  							name)));
  			return false;
  		}
  	}
  
  	/*
  	 * Disallow changing GUC_NOT_WHILE_SEC_REST values if we are inside a
  	 * security restriction context.  We can reject this regardless of
  	 * the GUC context or source, mainly because sources that it might be
  	 * reasonable to override for won't be seen while inside a function.
  	 *
  	 * Note: variables marked GUC_NOT_WHILE_SEC_REST should usually be marked
  	 * GUC_NO_RESET_ALL as well, because ResetAllOptions() doesn't check this.
  	 * An exception might be made if the reset value is assumed to be "safe".
  	 *
  	 * Note: this flag is currently used for "session_authorization" and
  	 * "role".  We need to prohibit changing these inside a local userid
  	 * context because when we exit it, GUC won't be notified, leaving things
  	 * out of sync.  (This could be fixed by forcing a new GUC nesting level,
  	 * but that would change behavior in possibly-undesirable ways.)  Also,
  	 * we prohibit changing these in a security-restricted operation because
  	 * otherwise RESET could be used to regain the session user's privileges.
  	 */
  	if (record->flags & GUC_NOT_WHILE_SEC_REST)
  	{
  		if (InLocalUserIdChange())
  		{
  			/*
  			 * Phrasing of this error message is historical, but it's the
  			 * most common case.
  			 */
  			ereport(elevel,
  					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  					 errmsg("cannot set parameter \"%s\" within security-definer function",
  							name)));
  			return false;
  		}
  		if (InSecurityRestrictedOperation())
  		{
  			ereport(elevel,
  					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  					 errmsg("cannot set parameter \"%s\" within security-restricted operation",
  							name)));
  			return false;
  		}
  	}
  
  	/*
  	 * Should we set reset/stacked values?	(If so, the behavior is not
  	 * transactional.)	This is done either when we get a default value from
  	 * the database's/user's/client's default settings or when we reset a
  	 * value to its default.
  	 */
  	makeDefault = changeVal && (source <= PGC_S_OVERRIDE) &&
  		((value != NULL) || source == PGC_S_DEFAULT);
  
  	/*
  	 * Ignore attempted set if overridden by previously processed setting.
  	 * However, if changeVal is false then plow ahead anyway since we are
  	 * trying to find out if the value is potentially good, not actually use
  	 * it. Also keep going if makeDefault is true, since we may want to set
  	 * the reset/stacked values even if we can't set the variable itself.
  	 */
  	if (record->source > source)
  	{
  		if (changeVal && !makeDefault)
  		{
  			elog(DEBUG3, "\"%s\": setting ignored because previous source is higher priority",
  				 name);
  			return true;
  		}
  		changeVal = false;
  	}
  
  	/*
  	 * Evaluate value and set variable.
  	 */
  	switch (record->vartype)
  	{
  		case PGC_BOOL:
  			{
  				struct config_bool *conf = (struct config_bool *) record;
  				bool		newval;
  
  				if (value)
  				{
  					if (!parse_bool(value, &newval))
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  						  errmsg("parameter \"%s\" requires a Boolean value",
  								 name)));
  						return false;
  					}
  				}
  				else if (source == PGC_S_DEFAULT)
  					newval = conf->boot_val;
  				else
  				{
  					newval = conf->reset_val;
  					source = conf->gen.reset_source;
  				}
  
  				/* Save old value to support transaction abort */
  				if (changeVal && !makeDefault)
  					push_old_value(&conf->gen, action);
  
  				if (conf->assign_hook)
  					if (!(*conf->assign_hook) (newval, changeVal, source))
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  							 errmsg("invalid value for parameter \"%s\": %d",
  									name, (int) newval)));
  						return false;
  					}
  
  				if (changeVal)
  				{
  					*conf->variable = newval;
  					conf->gen.source = source;
  				}
  				if (makeDefault)
  				{
  					GucStack   *stack;
  
  					if (conf->gen.reset_source <= source)
  					{
  						conf->reset_val = newval;
  						conf->gen.reset_source = source;
  					}
  					for (stack = conf->gen.stack; stack; stack = stack->prev)
  					{
  						if (stack->source <= source)
  						{
  							stack->prior.boolval = newval;
  							stack->source = source;
  						}
  					}
  				}
  				break;
  			}
  
  		case PGC_INT:
  			{
  				struct config_int *conf = (struct config_int *) record;
  				int			newval;
  
  				if (value)
  				{
  					const char *hintmsg;
  
  					if (!parse_int(value, &newval, conf->gen.flags, &hintmsg))
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  						 errmsg("invalid value for parameter \"%s\": \"%s\"",
  								name, value),
  								 hintmsg ? errhint("%s", hintmsg) : 0));
  						return false;
  					}
  					if (newval < conf->min || newval > conf->max)
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  								 errmsg("%d is outside the valid range for parameter \"%s\" (%d .. %d)",
  										newval, name, conf->min, conf->max)));
  						return false;
  					}
  
  					/*
  					 * If this is for "work_mem", its value also has to be smaller than or equal to
  					 * max_work_mem setting.
  					 */
  					if (strcmp(conf->gen.name, "work_mem") == 0 &&
  						newval > max_work_mem)
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  								 errmsg("%d is outside the valid range for parameter \"%s\" (%d .. %d)",
  										newval, name, conf->min, max_work_mem)));
  						return false;
  					}
  
  					/*
  					 * If this is for "max_work_mem", its value has to be greater than or equal to
  					 * current work_mem setting.
  					 */
  					if (strcmp(conf->gen.name, "max_work_mem") == 0 &&
  						newval < work_mem)
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  								 errmsg("%d is outside the valid range for parameter \"%s\" (%d .. %d)",
  										newval, name, work_mem, conf->max)));
  						return false;
  					}
  				}
  				else if (source == PGC_S_DEFAULT)
  					newval = conf->boot_val;
  				else
  				{
  					newval = conf->reset_val;
  					source = conf->gen.reset_source;
  				}
  
  				/* Save old value to support transaction abort */
  				if (changeVal && !makeDefault)
  					push_old_value(&conf->gen, action);
  
  				if (conf->assign_hook)
  					if (!(*conf->assign_hook) (newval, changeVal, source))
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  							 errmsg("invalid value for parameter \"%s\": %d",
  									name, newval)));
  						return false;
  					}
  
  				if (changeVal)
  				{
  					*conf->variable = newval;
  					conf->gen.source = source;
  				}
  				if (makeDefault)
  				{
  					GucStack   *stack;
  
  					if (conf->gen.reset_source <= source)
  					{
  						conf->reset_val = newval;
  						conf->gen.reset_source = source;
  					}
  					for (stack = conf->gen.stack; stack; stack = stack->prev)
  					{
  						if (stack->source <= source)
  						{
  							stack->prior.intval = newval;
  							stack->source = source;
  						}
  					}
  				}
  				break;
  			}
  
  		case PGC_REAL:
  			{
  				struct config_real *conf = (struct config_real *) record;
  				double		newval;
  
  				if (value)
  				{
  					if (!parse_real(value, &newval))
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  						  errmsg("parameter \"%s\" requires a numeric value",
  								 name)));
  						return false;
  					}
  					if (newval < conf->min || newval > conf->max)
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  								 errmsg("%g is outside the valid range for parameter \"%s\" (%g .. %g)",
  										newval, name, conf->min, conf->max)));
  						return false;
  					}
  				}
  				else if (source == PGC_S_DEFAULT)
  					newval = conf->boot_val;
  				else
  				{
  					newval = conf->reset_val;
  					source = conf->gen.reset_source;
  				}
  
  				/* Save old value to support transaction abort */
  				if (changeVal && !makeDefault)
  					push_old_value(&conf->gen, action);
  
  				if (conf->assign_hook)
  					if (!(*conf->assign_hook) (newval, changeVal, source))
  					{
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  							 errmsg("invalid value for parameter \"%s\": %g",
  									name, newval)));
  						return false;
  					}
  
  				if (changeVal)
  				{
  					*conf->variable = newval;
  					conf->gen.source = source;
  				}
  				if (makeDefault)
  				{
  					GucStack   *stack;
  
  					if (conf->gen.reset_source <= source)
  					{
  						conf->reset_val = newval;
  						conf->gen.reset_source = source;
  					}
  					for (stack = conf->gen.stack; stack; stack = stack->prev)
  					{
  						if (stack->source <= source)
  						{
  							stack->prior.realval = newval;
  							stack->source = source;
  						}
  					}
  				}
  				break;
  			}
  
  		case PGC_STRING:
  			{
  				struct config_string *conf = (struct config_string *) record;
  				char	   *newval;
  
  				if (value)
  				{
  					newval = guc_strdup(elevel, value);
  					if (newval == NULL)
  						return false;
  
  					/*
  					 * The only sort of "parsing" check we need to do is apply
  					 * truncation if GUC_IS_NAME.
  					 */
  					if (conf->gen.flags & GUC_IS_NAME)
  						truncate_identifier(newval, strlen(newval), true);
  				}
  				else if (source == PGC_S_DEFAULT)
  				{
  					if (conf->boot_val == NULL)
  						newval = NULL;
  					else
  					{
  						newval = guc_strdup(elevel, conf->boot_val);
  						if (newval == NULL)
  							return false;
  					}
  				}
  				else
  				{
  					/*
  					 * We could possibly avoid strdup here, but easier to make
  					 * this case work the same as the normal assignment case;
  					 * note the possible free of newval below.
  					 */
  					if (conf->reset_val == NULL)
  						newval = NULL;
  					else
  					{
  						newval = guc_strdup(elevel, conf->reset_val);
  						if (newval == NULL)
  							return false;
  					}
  					source = conf->gen.reset_source;
  				}
  
  				/* Save old value to support transaction abort */
  				if (changeVal && !makeDefault)
  					push_old_value(&conf->gen, action);
  
  				if (conf->assign_hook && newval)
  				{
  					const char *hookresult;
  
  					/*
  					 * If the hook ereports, we have to make sure we free
  					 * newval, else it will be a permanent memory leak.
  					 */
  					hookresult = call_string_assign_hook(conf->assign_hook,
  														 newval,
  														 changeVal,
  														 source);
  					if (hookresult == NULL)
  					{
  						free(newval);
  						ereport(elevel,
  								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  						 errmsg("invalid value for parameter \"%s\": \"%s\"",
  								name, value ? value : "")));
  						return false;
  					}
  					else if (hookresult != newval)
  					{
  						free(newval);
  
  						/*
  						 * Having to cast away const here is annoying, but the
  						 * alternative is to declare assign_hooks as returning
  						 * char*, which would mean they'd have to cast away
  						 * const, or as both taking and returning char*, which
  						 * doesn't seem attractive either --- we don't want
  						 * them to scribble on the passed str.
  						 */
  						newval = (char *) hookresult;
  					}
  				}
  
  				if (changeVal)
  				{
  					set_string_field(conf, conf->variable, newval);
  					conf->gen.source = source;
  				}
  				if (makeDefault)
  				{
  					GucStack   *stack;
  
  					if (conf->gen.reset_source <= source)
  					{
  						set_string_field(conf, &conf->reset_val, newval);
  						conf->gen.reset_source = source;
  					}
  					for (stack = conf->gen.stack; stack; stack = stack->prev)
  					{
  						if (stack->source <= source)
  						{
  							set_string_field(conf, &stack->prior.stringval,
  											 newval);
  							stack->source = source;
  						}
  					}
  				}
  				/* Perhaps we didn't install newval anywhere */
  				if (newval && !string_field_used(conf, newval))
  					free(newval);
  				break;
  			}
  	}
  
  	if (changeVal && (record->flags & GUC_REPORT))
  		ReportGUCOption(record);
  
  	return true;
  }
  
  
  /*
   * Set a config option to the given value. See also set_config_option,
   * this is just the wrapper to be called from outside GUC.	NB: this
   * is used only for non-transactional operations.
   */
  void
  SetConfigOption(const char *name, const char *value,
  				GucContext context, GucSource source)
  {
  	(void) set_config_option(name, value, context, source,
  							 GUC_ACTION_SET, true);
  }
  
  
  
  /*
   * Fetch the current value of the option `name'. If the option doesn't exist,
   * throw an ereport and don't return.
   *
   * The string is *not* allocated for modification and is really only
   * valid until the next call to configuration related functions.
   */
  const char *
  GetConfigOption(const char *name)
  {
  	struct config_generic *record;
  	static char buffer[256];
  
  	record = find_option(name, false, ERROR);
  	if (record == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_OBJECT),
  			   errmsg("unrecognized configuration parameter \"%s\"", name)));
  	if ((record->flags & GUC_SUPERUSER_ONLY) && !superuser())
  		ereport(ERROR,
  				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  				 errmsg("must be superuser to examine \"%s\"", name)));
  
  	switch (record->vartype)
  	{
  		case PGC_BOOL:
  			return *((struct config_bool *) record)->variable ? "on" : "off";
  
  		case PGC_INT:
  			snprintf(buffer, sizeof(buffer), "%d",
  					 *((struct config_int *) record)->variable);
  			return buffer;
  
  		case PGC_REAL:
  			snprintf(buffer, sizeof(buffer), "%g",
  					 *((struct config_real *) record)->variable);
  			return buffer;
  
  		case PGC_STRING:
  			return *((struct config_string *) record)->variable;
  	}
  	return NULL;
  }
  
  /*
   * Get the RESET value associated with the given option.
   *
   * Note: this is not re-entrant, due to use of static result buffer;
   * not to mention that a string variable could have its reset_val changed.
   * Beware of assuming the result value is good for very long.
   */
  const char *
  GetConfigOptionResetString(const char *name)
  {
  	struct config_generic *record;
  	static char buffer[256];
  
  	record = find_option(name, false, ERROR);
  	if (record == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_OBJECT),
  			   errmsg("unrecognized configuration parameter \"%s\"", name)));
  	if ((record->flags & GUC_SUPERUSER_ONLY) && !superuser())
  		ereport(ERROR,
  				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  				 errmsg("must be superuser to examine \"%s\"", name)));
  
  	switch (record->vartype)
  	{
  		case PGC_BOOL:
  			return ((struct config_bool *) record)->reset_val ? "on" : "off";
  
  		case PGC_INT:
  			snprintf(buffer, sizeof(buffer), "%d",
  					 ((struct config_int *) record)->reset_val);
  			return buffer;
  
  		case PGC_REAL:
  			snprintf(buffer, sizeof(buffer), "%g",
  					 ((struct config_real *) record)->reset_val);
  			return buffer;
  
  		case PGC_STRING:
  			return ((struct config_string *) record)->reset_val;
  	}
  	return NULL;
  }
  
  /*
   * Detect whether the given configuration option can only be set by
   * a superuser.
   */
  bool
  IsSuperuserConfigOption(const char *name)
  {
  	struct config_generic *record;
  
  	record = find_option(name, false, ERROR);
  	/* On an unrecognized name, don't error, just return false. */
  	if (record == NULL)
  		return false;
  	return (record->context == PGC_SUSET);
  }
  
  
  /*
   * GUC_complaint_elevel
   *		Get the ereport error level to use in an assign_hook's error report.
   *
   * This should be used by assign hooks that want to emit a custom error
   * report (in addition to the generic "invalid value for option FOO" that
   * guc.c will provide).  Note that the result might be ERROR or a lower
   * level, so the caller must be prepared for control to return from ereport,
   * or not.  If control does return, return false/NULL from the hook function.
   *
   * At some point it'd be nice to replace this with a mechanism that allows
   * the custom message to become the DETAIL line of guc.c's generic message.
   */
  int
  GUC_complaint_elevel(GucSource source)
  {
  	int			elevel;
  
  	if (source == PGC_S_FILE)
  	{
  		/*
  		 * To avoid cluttering the log, only the postmaster bleats loudly
  		 * about problems with the config file.
  		 */
  		elevel = IsUnderPostmaster ? DEBUG3 : LOG;
  	}
  	else if (source == PGC_S_OVERRIDE)
  	{
  		/*
  		 * If we're a postmaster child, this is probably "undo" during
  		 * transaction abort, so we don't want to clutter the log.  There's
  		 * a small chance of a real problem with an OVERRIDE setting,
  		 * though, so suppressing the message entirely wouldn't be desirable.
  		 */
  		elevel = IsUnderPostmaster ? DEBUG5 : LOG;
  	}
  	else if (source < PGC_S_INTERACTIVE)
  		elevel = LOG;
  	else
  		elevel = ERROR;
  
  	return elevel;
  }
  
  
  /*
   * flatten_set_variable_args
   *		Given a parsenode List as emitted by the grammar for SET,
   *		convert to the flat string representation used by GUC.
   *
   * We need to be told the name of the variable the args are for, because
   * the flattening rules vary (ugh).
   *
   * The result is NULL if args is NIL (ie, SET ... TO DEFAULT), otherwise
   * a palloc'd string.
   */
  static char *
  flatten_set_variable_args(const char *name, List *args)
  {
  	struct config_generic *record;
  	int			flags;
  	StringInfoData buf;
  	ListCell   *l;
  
  	/* Fast path if just DEFAULT */
  	if (args == NIL)
  		return NULL;
  
  	/* Else get flags for the variable */
  	record = find_option(name, true, ERROR);
  	if (record == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_OBJECT),
  			   errmsg("unrecognized configuration parameter \"%s\"", name)));
  
  	flags = record->flags;
  
  	/* Complain if list input and non-list variable */
  	if ((flags & GUC_LIST_INPUT) == 0 &&
  		list_length(args) != 1)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("SET %s takes only one argument", name)));
  
  	initStringInfo(&buf);
  
  	foreach(l, args)
  	{
  		A_Const    *arg = (A_Const *) lfirst(l);
  		char	   *val;
  
  		if (l != list_head(args))
  			appendStringInfo(&buf, ", ");
  
  		if (!IsA(arg, A_Const))
  			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(arg));
  
  		switch (nodeTag(&arg->val))
  		{
  			case T_Integer:
  				appendStringInfo(&buf, "%ld", intVal(&arg->val));
  				break;
  			case T_Float:
  				/* represented as a string, so just copy it */
  				appendStringInfoString(&buf, strVal(&arg->val));
  				break;
  			case T_String:
  				val = strVal(&arg->val);
  				if (arg->typname != NULL)
  				{
  					/*
  					 * Must be a ConstInterval argument for TIME ZONE. Coerce
  					 * to interval and back to normalize the value and account
  					 * for any typmod.
  					 */
  					Oid			typoid;
  					int32		typmod;
  					Datum		interval;
  					char	   *intervalout;
  
  					typoid = typenameTypeId(NULL, arg->typname, &typmod);
  					Assert(typoid == INTERVALOID);
  
  					interval =
  						DirectFunctionCall3(interval_in,
  											CStringGetDatum(val),
  											ObjectIdGetDatum(InvalidOid),
  											Int32GetDatum(typmod));
  
  					intervalout =
  						DatumGetCString(DirectFunctionCall1(interval_out,
  															interval));
  					appendStringInfo(&buf, "INTERVAL '%s'", intervalout);
  				}
  				else
  				{
  					/*
  					 * Plain string literal or identifier.	For quote mode,
  					 * quote it if it's not a vanilla identifier.
  					 */
  					if (flags & GUC_LIST_QUOTE)
  						appendStringInfoString(&buf, quote_identifier(val));
  					else
  						appendStringInfoString(&buf, val);
  				}
  				break;
  			default:
  				elog(ERROR, "unrecognized node type: %d",
  					 (int) nodeTag(&arg->val));
  				break;
  		}
  	}
  
  	return buf.data;
  }
  
  
  /*
   * SET command
   */
  void
  ExecSetVariableStmt(VariableSetStmt *stmt)
  {
  	GucAction	action = stmt->is_local ? GUC_ACTION_LOCAL : GUC_ACTION_SET;
  
  	switch (stmt->kind)
  	{
  		case VAR_SET_VALUE:
  		case VAR_SET_CURRENT:
  			set_config_option(stmt->name,
  							  ExtractSetVariableArgs(stmt),
  							  (superuser() ? PGC_SUSET : PGC_USERSET),
  							  PGC_S_SESSION,
  							  action,
  							  true);
  			break;
  		case VAR_SET_MULTI:
  
  			/*
  			 * Special case for special SQL syntax that effectively sets more
  			 * than one variable per statement.
  			 */
  			if (strcmp(stmt->name, "TRANSACTION") == 0)
  			{
  				ListCell   *head;
  
  				foreach(head, stmt->args)
  				{
  					DefElem    *item = (DefElem *) lfirst(head);
  
  					if (strcmp(item->defname, "transaction_isolation") == 0)
  						SetPGVariable("transaction_isolation",
  									  list_make1(item->arg), stmt->is_local);
  					else if (strcmp(item->defname, "transaction_read_only") == 0)
  						SetPGVariable("transaction_read_only",
  									  list_make1(item->arg), stmt->is_local);
  					else
  						elog(ERROR, "unexpected SET TRANSACTION element: %s",
  							 item->defname);
  				}
  			}
  			else if (strcmp(stmt->name, "SESSION CHARACTERISTICS") == 0)
  			{
  				ListCell   *head;
  
  				foreach(head, stmt->args)
  				{
  					DefElem    *item = (DefElem *) lfirst(head);
  
  					if (strcmp(item->defname, "transaction_isolation") == 0)
  						SetPGVariable("default_transaction_isolation",
  									  list_make1(item->arg), stmt->is_local);
  					else if (strcmp(item->defname, "transaction_read_only") == 0)
  						SetPGVariable("default_transaction_read_only",
  									  list_make1(item->arg), stmt->is_local);
  					else
  						elog(ERROR, "unexpected SET SESSION element: %s",
  							 item->defname);
  				}
  			}
  			else
  				elog(ERROR, "unexpected SET MULTI element: %s",
  					 stmt->name);
  			break;
  		case VAR_SET_DEFAULT:
  		case VAR_RESET:
  			set_config_option(stmt->name,
  							  NULL,
  							  (superuser() ? PGC_SUSET : PGC_USERSET),
  							  PGC_S_SESSION,
  							  action,
  							  true);
  			break;
  		case VAR_RESET_ALL:
  			ResetAllOptions();
  			break;
  	}
  }
  
  /*
   * Get the value to assign for a VariableSetStmt, or NULL if it's RESET.
   * The result is palloc'd.
   *
   * This is exported for use by actions such as ALTER ROLE SET.
   */
  char *
  ExtractSetVariableArgs(VariableSetStmt *stmt)
  {
  	switch (stmt->kind)
  	{
  		case VAR_SET_VALUE:
  			return flatten_set_variable_args(stmt->name, stmt->args);
  		case VAR_SET_CURRENT:
  			return GetConfigOptionByName(stmt->name, NULL);
  		default:
  			return NULL;
  	}
  }
  
  
  
  /*
   * SetPGVariable - SET command exported as an easily-C-callable function.
   *
   * This provides access to SET TO value, as well as SET TO DEFAULT (expressed
   * by passing args == NIL), but not SET FROM CURRENT functionality.
   */
  void
  SetPGVariable(const char *name, List *args, bool is_local)
  {
  	SetPGVariableOptDispatch(name, args, is_local, true);
  }
  
  /* GPDB: Like SetPGVariable, but with extra 'gp_dispatch' parameter.  */
  void
  SetPGVariableOptDispatch(const char *name, List *args, bool is_local, bool gp_dispatch)
  {
  	char	   *argstring = flatten_set_variable_args(name, args);
  
  	/* Note SET DEFAULT (argstring == NULL) is equivalent to RESET */
  	set_config_option(name,
  					  argstring,
  					  (superuser() ? PGC_SUSET : PGC_USERSET),
  					  PGC_S_SESSION,
  					  is_local ? GUC_ACTION_LOCAL : GUC_ACTION_SET,
  					  true);
  
  	if (Gp_role == GP_ROLE_DISPATCH && !IsBootstrapProcessingMode())
  	{
  
  		ListCell * l;
  		StringInfoData buffer;
  
  		initStringInfo( &buffer );
  
          if (argstring == NULL)
          {
              appendStringInfo(&buffer, "RESET %s", name);
              args = NIL;
          }
          else
          {
              appendStringInfo(&buffer, "SET ");
  		    if (is_local)
  			    appendStringInfo(&buffer, "LOCAL ");
  
  		    appendStringInfo(&buffer, "%s TO ", name);
          }
  
  		foreach(l, args)
  		{
  			A_Const    *arg = (A_Const *) lfirst(l);
  			char	   *val;
  
  			if (l != list_head(args))
  				appendStringInfo(&buffer, ", ");
  
  			if (!IsA(arg, A_Const))
  				elog(ERROR, "unrecognized node type: %d", (int) nodeTag(arg));
  
  			switch (nodeTag(&arg->val))
  			{
  				case T_Integer:
  					appendStringInfo(&buffer, "%ld", intVal(&arg->val));
  					break;
  				case T_Float:
  					/* represented as a string, so just copy it */
  					appendStringInfoString(&buffer, strVal(&arg->val));
  					break;
  				case T_String:
  					val = strVal(&arg->val);
  
  						/*
  						 * Plain string literal or identifier., quote it
  						 */
  
  					if (val[0] != '\'')
  						appendStringInfo(&buffer, "%s", quote_literal_internal(val));
  					else
  						appendStringInfo(&buffer, "%s",val);
  
  
  					break;
  				default:
  					elog(ERROR, "unrecognized node type: %d",
  						 (int) nodeTag(&arg->val));
  					break;
  			}
  		}
  
  		if (gp_dispatch)
  		{
  			CdbSetGucOnAllGangs( buffer.data, false, /*no txn*/ false );
  		}
  	}
  }
  
  /*
   * SET command wrapped as a SQL callable function.
   */
  Datum
  set_config_by_name(PG_FUNCTION_ARGS)
  {
  	char	   *name;
  	char	   *value;
  	char	   *new_value;
  	bool		is_local;
  	text	   *result_text;
  
  	if (PG_ARGISNULL(0))
  		ereport(ERROR,
  				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
  				 errmsg("SET requires parameter name")));
  
  	/* Get the GUC variable name */
  	name = DatumGetCString(DirectFunctionCall1(textout, PG_GETARG_DATUM(0)));
  
  	/* Get the desired value or set to NULL for a reset request */
  	if (PG_ARGISNULL(1))
  		value = NULL;
  	else
  		value = DatumGetCString(DirectFunctionCall1(textout, PG_GETARG_DATUM(1)));
  
  	/*
  	 * Get the desired state of is_local. Default to false if provided value
  	 * is NULL
  	 */
  	if (PG_ARGISNULL(2))
  		is_local = false;
  	else
  		is_local = PG_GETARG_BOOL(2);
  
  	/* Note SET DEFAULT (argstring == NULL) is equivalent to RESET */
  	set_config_option(name,
  					  value,
  					  (superuser() ? PGC_SUSET : PGC_USERSET),
  					  PGC_S_SESSION,
  					  is_local ? GUC_ACTION_LOCAL : GUC_ACTION_SET,
  					  true);
  
      if (Gp_role == GP_ROLE_DISPATCH && !IsBootstrapProcessingMode())
      {
  			StringInfoData buffer;
  			initStringInfo(&buffer);
  			appendStringInfo(&buffer, "SET ");
  			if (is_local)
  					appendStringInfo(&buffer, "LOCAL ");
  			appendStringInfo(&buffer, "%s TO '%s'", name, value);
  			CdbSetGucOnAllGangs(buffer.data,
  								   false /* cancelOnError */,
  								   false /* no two phase commit */);
      }
  
  	/* get the new current value */
  	new_value = GetConfigOptionByName(name, NULL);
  
  	/* Convert return string to text */
  	result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(new_value)));
  
  	/* return it */
  	PG_RETURN_TEXT_P(result_text);
  }
  
  
  /*
   * Common code for DefineCustomXXXVariable subroutines: allocate the
   * new variable's config struct and fill in generic fields.
   */
  static struct config_generic *
  init_custom_variable(const char *name,
  					 const char *short_desc,
  					 const char *long_desc,
  					 GucContext context,
  					 enum config_type type,
  					 size_t sz)
  {
  	struct config_generic *gen;
  
  	gen = (struct config_generic *) guc_malloc(ERROR, sz);
  	memset(gen, 0, sz);
  
  	gen->name = guc_strdup(ERROR, name);
  	gen->context = context;
  	gen->group = CUSTOM_OPTIONS;
  	gen->short_desc = short_desc;
  	gen->long_desc = long_desc;
  	gen->vartype = type;
  
  	return gen;
  }
  
  /*
   * Common code for DefineCustomXXXVariable subroutines: insert the new
   * variable into the GUC variable array, replacing any placeholder.
   */
  static void
  define_custom_variable(struct config_generic * variable)
  {
  	const char *name = variable->name;
  	const char **nameAddr = &name;
  	const char *value;
  	struct config_string *pHolder;
  	struct config_generic **res;
  
  	res = (struct config_generic **) bsearch((void *) &nameAddr,
  											 (void *) guc_variables,
  											 num_guc_variables,
  											 sizeof(struct config_generic *),
  											 guc_var_compare);
  	if (res == NULL)
  	{
  		/* No placeholder to replace, so just add it */
  		add_guc_variable(variable, ERROR);
  		return;
  	}
  
  	/*
  	 * This better be a placeholder
  	 */
  	if (((*res)->flags & GUC_CUSTOM_PLACEHOLDER) == 0)
  		ereport(ERROR,
  				(errcode(ERRCODE_INTERNAL_ERROR),
  				 errmsg("attempt to redefine parameter \"%s\"", name)));
  
  	Assert((*res)->vartype == PGC_STRING);
  	pHolder = (struct config_string *) (*res);
  
  	/*
  	 * Replace the placeholder. We aren't changing the name, so no re-sorting
  	 * is necessary
  	 */
  	*res = variable;
  
  	/*
  	 * Assign the string value stored in the placeholder to the real variable.
  	 *
  	 * XXX this is not really good enough --- it should be a nontransactional
  	 * assignment, since we don't want it to roll back if the current xact
  	 * fails later.
  	 */
  	value = *pHolder->variable;
  
  	if (value)
  		set_config_option(name, value,
  						  pHolder->gen.context, pHolder->gen.source,
  						  GUC_ACTION_SET, true);
  
  	/*
  	 * Free up as much as we conveniently can of the placeholder structure
  	 * (this neglects any stack items...)
  	 */
  	set_string_field(pHolder, pHolder->variable, NULL);
  	set_string_field(pHolder, &pHolder->reset_val, NULL);
  
  	free(pHolder);
  }
  
  void
  DefineCustomBoolVariable(const char *name,
  						 const char *short_desc,
  						 const char *long_desc,
  						 bool *valueAddr,
  						 GucContext context,
  						 GucBoolAssignHook assign_hook,
  						 GucShowHook show_hook)
  {
  	struct config_bool *var;
  
  	var = (struct config_bool *)
  		init_custom_variable(name, short_desc, long_desc, context,
  							 PGC_BOOL, sizeof(struct config_bool));
  	var->variable = valueAddr;
  	var->boot_val = *valueAddr;
  	var->reset_val = *valueAddr;
  	var->assign_hook = assign_hook;
  	var->show_hook = show_hook;
  	define_custom_variable(&var->gen);
  }
  
  void
  DefineCustomIntVariable(const char *name,
  						const char *short_desc,
  						const char *long_desc,
  						int *valueAddr,
  						int minValue,
  						int maxValue,
  						GucContext context,
  						GucIntAssignHook assign_hook,
  						GucShowHook show_hook)
  {
  	struct config_int *var;
  
  	var = (struct config_int *)
  		init_custom_variable(name, short_desc, long_desc, context,
  							 PGC_INT, sizeof(struct config_int));
  	var->variable = valueAddr;
  	var->boot_val = *valueAddr;
  	var->reset_val = *valueAddr;
  	var->min = minValue;
  	var->max = maxValue;
  	var->assign_hook = assign_hook;
  	var->show_hook = show_hook;
  	define_custom_variable(&var->gen);
  }
  
  void
  DefineCustomRealVariable(const char *name,
  						 const char *short_desc,
  						 const char *long_desc,
  						 double *valueAddr,
  						 double minValue,
  						 double maxValue,
  						 GucContext context,
  						 GucRealAssignHook assign_hook,
  						 GucShowHook show_hook)
  {
  	struct config_real *var;
  
  	var = (struct config_real *)
  		init_custom_variable(name, short_desc, long_desc, context,
  							 PGC_REAL, sizeof(struct config_real));
  	var->variable = valueAddr;
  	var->boot_val = *valueAddr;
  	var->reset_val = *valueAddr;
  	var->min = minValue;
  	var->max = maxValue;
  	var->assign_hook = assign_hook;
  	var->show_hook = show_hook;
  	define_custom_variable(&var->gen);
  }
  
  void
  DefineCustomStringVariable(const char *name,
  						   const char *short_desc,
  						   const char *long_desc,
  						   char **valueAddr,
  						   GucContext context,
  						   GucStringAssignHook assign_hook,
  						   GucShowHook show_hook)
  {
  	struct config_string *var;
  
  	var = (struct config_string *)
  		init_custom_variable(name, short_desc, long_desc, context,
  							 PGC_STRING, sizeof(struct config_string));
  	var->variable = valueAddr;
  	var->boot_val = *valueAddr;
  	/* we could probably do without strdup, but keep it like normal case */
  	if (var->boot_val)
  		var->reset_val = guc_strdup(ERROR, var->boot_val);
  	var->assign_hook = assign_hook;
  	var->show_hook = show_hook;
  	define_custom_variable(&var->gen);
  }
  
  void
  EmitWarningsOnPlaceholders(const char *className)
  {
  	struct config_generic **vars = guc_variables;
  	struct config_generic **last = vars + num_guc_variables;
  
  	int			nameLen = strlen(className);
  
  	while (vars < last)
  	{
  		struct config_generic *var = *vars++;
  
  		if ((var->flags & GUC_CUSTOM_PLACEHOLDER) != 0 &&
  			strncmp(className, var->name, nameLen) == 0 &&
  			var->name[nameLen] == GUC_QUALIFIER_SEPARATOR)
  		{
  			if (Gp_role != GP_ROLE_EXECUTE)
  			ereport(INFO,
  					(errcode(ERRCODE_UNDEFINED_OBJECT),
  					 errmsg("unrecognized configuration parameter \"%s\"", var->name)));
  		}
  	}
  }
  
  
  /*
   * SHOW command
   */
  void
  GetPGVariable(const char *name, DestReceiver *dest)
  {
  	if (guc_name_compare(name, "all") == 0)
  		ShowAllGUCConfig(dest);
  	else
  		ShowGUCConfigOption(name, dest);
  }
  
  TupleDesc
  GetPGVariableResultDesc(const char *name)
  {
  	TupleDesc	tupdesc;
  
  	if (guc_name_compare(name, "all") == 0)
  	{
  		/* need a tuple descriptor representing three TEXT columns */
  		tupdesc = CreateTemplateTupleDesc(3, false);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "setting",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "description",
  						   TEXTOID, -1, 0);
  
  	}
  	else
  	{
  		const char *varname;
  
  		/* Get the canonical spelling of name */
  		(void) GetConfigOptionByName(name, &varname);
  
  		/* need a tuple descriptor representing a single TEXT column */
  		tupdesc = CreateTemplateTupleDesc(1, false);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 1, varname,
  						   TEXTOID, -1, 0);
  	}
  	return tupdesc;
  }
  
  
  /*
   * SHOW command
   */
  static void
  ShowGUCConfigOption(const char *name, DestReceiver *dest)
  {
  	TupOutputState *tstate;
  	TupleDesc	tupdesc;
  	const char *varname;
  	char	   *value;
  
  	/* Get the value and canonical spelling of name */
  	value = GetConfigOptionByName(name, &varname);
  
  	/* need a tuple descriptor representing a single TEXT column */
  	tupdesc = CreateTemplateTupleDesc(1, false);
  	TupleDescInitEntry(tupdesc, (AttrNumber) 1, varname,
  					   TEXTOID, -1, 0);
  
  	/* prepare for projection of tuples */
  	tstate = begin_tup_output_tupdesc(dest, tupdesc);
  
  	/* Send it */
  	do_text_output_oneline(tstate, value);
  
  	end_tup_output(tstate);
  }
  
  /*
   * SHOW ALL command
   */
  static void
  ShowAllGUCConfig(DestReceiver *dest)
  {
  	bool		am_superuser = superuser();
  	int			i;
  	TupOutputState *tstate;
  	TupleDesc	tupdesc;
  	char	   *values[3];
  
  	/* need a tuple descriptor representing three TEXT columns */
  	tupdesc = CreateTemplateTupleDesc(3, false);
  	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
  					   TEXTOID, -1, 0);
  	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "setting",
  					   TEXTOID, -1, 0);
  	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "description",
  					   TEXTOID, -1, 0);
  
  
  	/* prepare for projection of tuples */
  	tstate = begin_tup_output_tupdesc(dest, tupdesc);
  
  	for (i = 0; i < num_guc_variables; i++)
  	{
  		struct config_generic *conf = guc_variables[i];
  
  		if ((conf->flags & GUC_NO_SHOW_ALL) ||
  			((conf->flags & GUC_SUPERUSER_ONLY) && !am_superuser))
  			continue;
  
  		/* assign to the values array */
  		values[0] = (char *) conf->name;
  		values[1] = _ShowOption(conf, true);
  		values[2] = (char *) conf->short_desc;
  
  		/* send it to dest */
  		do_tup_output(tstate, values);
  
  		/* clean up */
  		if (values[1] != NULL)
  			pfree(values[1]);
  	}
  
  	end_tup_output(tstate);
  }
  
  /*
   * Return GUC variable value by name; optionally return canonical
   * form of name.  Return value is palloc'd.
   */
  char *
  GetConfigOptionByName(const char *name, const char **varname)
  {
  	struct config_generic *record;
  
  	record = find_option(name, false, ERROR);
  	if (record == NULL)
  		ereport(ERROR,
  				(errcode(ERRCODE_UNDEFINED_OBJECT),
  			   errmsg("unrecognized configuration parameter \"%s\"", name)));
  	if ((record->flags & GUC_SUPERUSER_ONLY) && !superuser())
  		ereport(ERROR,
  				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  				 errmsg("must be superuser to examine \"%s\"", name)));
  
  	if (varname)
  		*varname = record->name;
  
  	return _ShowOption(record, true);
  }
  
  /*
   * Return GUC variable value by variable number; optionally return canonical
   * form of name.  Return value is palloc'd.
   */
  void
  GetConfigOptionByNum(int varnum, const char **values, bool *noshow)
  {
  	char		buffer[256];
  	struct config_generic *conf;
  
  	/* check requested variable number valid */
  	Assert((varnum >= 0) && (varnum < num_guc_variables));
  
  	conf = guc_variables[varnum];
  
  	if (noshow)
  	{
  		if ((conf->flags & GUC_NO_SHOW_ALL) ||
  			((conf->flags & GUC_SUPERUSER_ONLY) && !superuser()))
  			*noshow = true;
  		else
  			*noshow = false;
  	}
  
  	/* first get the generic attributes */
  
  	/* name */
  	values[0] = conf->name;
  
  	/* setting : use _ShowOption in order to avoid duplicating the logic */
  	values[1] = _ShowOption(conf, false);
  
  	/* unit */
  	if (conf->vartype == PGC_INT)
  	{
  		static char buf[8];
  
  		switch (conf->flags & (GUC_UNIT_MEMORY | GUC_UNIT_TIME))
  		{
  			case GUC_UNIT_KB:
  				values[2] = "kB";
  				break;
  			case GUC_UNIT_BLOCKS:
  				snprintf(buf, sizeof(buf), "%dkB", BLCKSZ / 1024);
  				values[2] = buf;
  				break;
  			case GUC_UNIT_XBLOCKS:
  				snprintf(buf, sizeof(buf), "%dkB", XLOG_BLCKSZ / 1024);
  				values[2] = buf;
  				break;
  			case GUC_UNIT_MS:
  				values[2] = "ms";
  				break;
  			case GUC_UNIT_S:
  				values[2] = "s";
  				break;
  			case GUC_UNIT_MIN:
  				values[2] = "min";
  				break;
  			default:
  				values[2] = "";
  				break;
  		}
  	}
  	else
  		values[2] = NULL;
  
  	/* group */
  	values[3] = config_group_names[conf->group];
  
  	/* short_desc */
  	values[4] = conf->short_desc;
  
  	/* extra_desc */
  	values[5] = conf->long_desc;
  
  	/* context */
  	values[6] = GucContext_Names[conf->context];
  
  	/* vartype */
  	values[7] = config_type_names[conf->vartype];
  
  	/* source */
  	values[8] = GucSource_Names[conf->source];
  
  	/* now get the type specifc attributes */
  	switch (conf->vartype)
  	{
  		case PGC_BOOL:
  			{
  				/* min_val */
  				values[9] = NULL;
  
  				/* max_val */
  				values[10] = NULL;
  			}
  			break;
  
  		case PGC_INT:
  			{
  				struct config_int *lconf = (struct config_int *) conf;
  
  				/* min_val */
  				snprintf(buffer, sizeof(buffer), "%d", lconf->min);
  				values[9] = pstrdup(buffer);
  
  				/* max_val */
  				snprintf(buffer, sizeof(buffer), "%d", lconf->max);
  				values[10] = pstrdup(buffer);
  			}
  			break;
  
  		case PGC_REAL:
  			{
  				struct config_real *lconf = (struct config_real *) conf;
  
  				/* min_val */
  				snprintf(buffer, sizeof(buffer), "%g", lconf->min);
  				values[9] = pstrdup(buffer);
  
  				/* max_val */
  				snprintf(buffer, sizeof(buffer), "%g", lconf->max);
  				values[10] = pstrdup(buffer);
  			}
  			break;
  
  		case PGC_STRING:
  			{
  				/* min_val */
  				values[9] = NULL;
  
  				/* max_val */
  				values[10] = NULL;
  			}
  			break;
  
  		default:
  			{
  				/*
  				 * should never get here, but in case we do, set 'em to NULL
  				 */
  
  				/* min_val */
  				values[9] = NULL;
  
  				/* max_val */
  				values[10] = NULL;
  			}
  			break;
  	}
  }
  
  /*
   * Return the total number of GUC variables
   */
  int
  GetNumConfigOptions(void)
  {
  	return num_guc_variables;
  }
  
  /*
   * show_config_by_name - equiv to SHOW X command but implemented as
   * a function.
   */
  Datum
  show_config_by_name(PG_FUNCTION_ARGS)
  {
  	char	   *varname;
  	char	   *varval;
  	text	   *result_text;
  
  	/* Get the GUC variable name */
  	varname = DatumGetCString(DirectFunctionCall1(textout, PG_GETARG_DATUM(0)));
  
  	/* Get the value */
  	varval = GetConfigOptionByName(varname, NULL);
  
  	/* Convert to text */
  	result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(varval)));
  
  	/* return it */
  	PG_RETURN_TEXT_P(result_text);
  }
  
  /*
   * show_all_settings - equiv to SHOW ALL command but implemented as
   * a Table Function.
   */
  #define NUM_PG_SETTINGS_ATTS	11
  
  Datum
  show_all_settings(PG_FUNCTION_ARGS)
  {
  	FuncCallContext *funcctx;
  	TupleDesc	tupdesc;
  	int			call_cntr;
  	int			max_calls;
  	AttInMetadata *attinmeta;
  	MemoryContext oldcontext;
  
  	/* stuff done only on the first call of the function */
  	if (SRF_IS_FIRSTCALL())
  	{
  		/* create a function context for cross-call persistence */
  		funcctx = SRF_FIRSTCALL_INIT();
  
  		/*
  		 * switch to memory context appropriate for multiple function calls
  		 */
  		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
  
  		/*
  		 * need a tuple descriptor representing NUM_PG_SETTINGS_ATTS columns
  		 * of the appropriate types
  		 */
  		tupdesc = CreateTemplateTupleDesc(NUM_PG_SETTINGS_ATTS, false);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "setting",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "unit",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 4, "category",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 5, "short_desc",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 6, "extra_desc",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 7, "context",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 8, "vartype",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 9, "source",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 10, "min_val",
  						   TEXTOID, -1, 0);
  		TupleDescInitEntry(tupdesc, (AttrNumber) 11, "max_val",
  						   TEXTOID, -1, 0);
  
  		/*
  		 * Generate attribute metadata needed later to produce tuples from raw
  		 * C strings
  		 */
  		attinmeta = TupleDescGetAttInMetadata(tupdesc);
  		funcctx->attinmeta = attinmeta;
  
  		/* total number of tuples to be returned */
  		funcctx->max_calls = GetNumConfigOptions();
  
  		MemoryContextSwitchTo(oldcontext);
  	}
  
  	/* stuff done on every call of the function */
  	funcctx = SRF_PERCALL_SETUP();
  
  	call_cntr = funcctx->call_cntr;
  	max_calls = funcctx->max_calls;
  	attinmeta = funcctx->attinmeta;
  
  	if (call_cntr < max_calls)	/* do when there is more left to send */
  	{
  		char	   *values[NUM_PG_SETTINGS_ATTS];
  		bool		noshow;
  		HeapTuple	tuple;
  		Datum		result;
  
  		/*
  		 * Get the next visible GUC variable name and value
  		 */
  		do
  		{
  			GetConfigOptionByNum(call_cntr, (const char **) values, &noshow);
  			if (noshow)
  			{
  				/* bump the counter and get the next config setting */
  				call_cntr = ++funcctx->call_cntr;
  
  				/* make sure we haven't gone too far now */
  				if (call_cntr >= max_calls)
  					SRF_RETURN_DONE(funcctx);
  			}
  		} while (noshow);
  
  		/* build a tuple */
  		tuple = BuildTupleFromCStrings(attinmeta, values);
  
  		/* make the tuple into a datum */
  		result = HeapTupleGetDatum(tuple);
  
  		SRF_RETURN_NEXT(funcctx, result);
  	}
  	else
  	{
  		/* do when there is no more left */
  		SRF_RETURN_DONE(funcctx);
  	}
  }
  
  static char *
  _ShowOption(struct config_generic * record, bool use_units)
  {
  	char		buffer[256];
  	const char *val;
  
  	switch (record->vartype)
  	{
  		case PGC_BOOL:
  			{
  				struct config_bool *conf = (struct config_bool *) record;
  
  				if (conf->show_hook)
  					val = (*conf->show_hook) ();
  				else
  					val = *conf->variable ? "on" : "off";
  			}
  			break;
  
  		case PGC_INT:
  			{
  				struct config_int *conf = (struct config_int *) record;
  
  				if (conf->show_hook)
  					val = (*conf->show_hook) ();
  				else
  				{
  					/*
  					 * Use int64 arithmetic to avoid overflows in units
  					 * conversion.  If INT64_IS_BUSTED we might overflow
  					 * anyway and print bogus answers, but there are few
  					 * enough such machines that it doesn't seem worth
  					 * trying harder.
  					 */
  					int64		result = *conf->variable;
  					const char *unit;
  
  					if (use_units && result > 0 &&
  						(record->flags & GUC_UNIT_MEMORY))
  					{
  						switch (record->flags & GUC_UNIT_MEMORY)
  						{
  							case GUC_UNIT_BLOCKS:
  								result *= BLCKSZ / 1024;
  								break;
  							case GUC_UNIT_XBLOCKS:
  								result *= XLOG_BLCKSZ / 1024;
  								break;
  						}
  
  						if (result % KB_PER_GB == 0)
  						{
  							result /= KB_PER_GB;
  							unit = "GB";
  						}
  						else if (result % KB_PER_MB == 0)
  						{
  							result /= KB_PER_MB;
  							unit = "MB";
  						}
  						else
  						{
  							unit = "kB";
  						}
  					}
  					else if (use_units && result > 0 &&
  							 (record->flags & GUC_UNIT_TIME))
  					{
  						switch (record->flags & GUC_UNIT_TIME)
  						{
  							case GUC_UNIT_S:
  								result *= MS_PER_S;
  								break;
  							case GUC_UNIT_MIN:
  								result *= MS_PER_MIN;
  								break;
  						}
  
  						if (result % MS_PER_D == 0)
  						{
  							result /= MS_PER_D;
  							unit = "d";
  						}
  						else if (result % MS_PER_H == 0)
  						{
  							result /= MS_PER_H;
  							unit = "h";
  						}
  						else if (result % MS_PER_MIN == 0)
  						{
  							result /= MS_PER_MIN;
  							unit = "min";
  						}
  						else if (result % MS_PER_S == 0)
  						{
  							result /= MS_PER_S;
  							unit = "s";
  						}
  						else
  						{
  							unit = "ms";
  						}
  					}
  					else
  						unit = "";
  
  					snprintf(buffer, sizeof(buffer), INT64_FORMAT "%s",
  							 result, unit);
  					val = buffer;
  				}
  			}
  			break;
  
  		case PGC_REAL:
  			{
  				struct config_real *conf = (struct config_real *) record;
  
  				if (conf->show_hook)
  					val = (*conf->show_hook) ();
  				else
  				{
  					char		unit[4];
  					double		result = *conf->variable;
  
  					if (use_units && result > 0 && (record->flags & GUC_UNIT_MEMORY))
  					{
                          double result_gb;
                          double result_mb;
  
                          switch (record->flags & GUC_UNIT_MEMORY)
  						{
  							case GUC_UNIT_BLOCKS:
  								result *= BLCKSZ / 1024;
  								break;
  							case GUC_UNIT_XBLOCKS:
  								result *= XLOG_BLCKSZ / 1024;
  								break;
  						}
  
                          result_gb = result / KB_PER_GB;
                          result_mb = result / KB_PER_MB;
  
  						if (result_gb >= 1.0 &&
                              result_gb * KB_PER_GB == result)
  						{
  							result = result_gb;
  							strcpy(unit, "GB");
  						}
  						else if (result_mb >= 1.0 &&
                                   result_mb * KB_PER_MB == result)
  						{
  							result = result_mb;
  							strcpy(unit, "MB");
  						}
  						else
  							strcpy(unit, "kB");
  					}
  					else
  						strcpy(unit, "");
  
  					snprintf(buffer, sizeof(buffer), "%g%s", result, unit);
  					val = buffer;
  				}
  			}
  			break;
  
  		case PGC_STRING:
  			{
  				struct config_string *conf = (struct config_string *) record;
  
  				if (conf->show_hook)
  					val = (*conf->show_hook) ();
  				else if (*conf->variable && **conf->variable)
  					val = *conf->variable;
  				else
  					val = "";
  			}
  			break;
  
  		default:
  			/* just to keep compiler quiet */
  			val = "???";
  			break;
  	}
  
  	return pstrdup(val);
  }
  
  
  /*
   * Attempt (badly) to detect if a proposed new GUC setting is the same
   * as the current value.
   *
   * XXX this does not really work because it doesn't account for the
   * effects of canonicalization of string values by assign_hooks.
   */
  static bool
  is_newvalue_equal(struct config_generic * record, const char *newvalue)
  {
  	/* newvalue == NULL isn't supported */
  	Assert(newvalue != NULL);
  
  	switch (record->vartype)
  	{
  		case PGC_BOOL:
  			{
  				struct config_bool *conf = (struct config_bool *) record;
  				bool		newval;
  
  				return parse_bool(newvalue, &newval)
  					&& *conf->variable == newval;
  			}
  		case PGC_INT:
  			{
  				struct config_int *conf = (struct config_int *) record;
  				int			newval;
  
  				return parse_int(newvalue, &newval, record->flags, NULL)
  					&& *conf->variable == newval;
  			}
  		case PGC_REAL:
  			{
  				struct config_real *conf = (struct config_real *) record;
  				double		newval;
  
  				return parse_real(newvalue, &newval)
  					&& *conf->variable == newval;
  			}
  		case PGC_STRING:
  			{
  				struct config_string *conf = (struct config_string *) record;
  
  				return *conf->variable != NULL &&
  					strcmp(*conf->variable, newvalue) == 0;
  			}
  	}
  
  	return false;
  }
  
  
  #ifdef EXEC_BACKEND
  
  /*
   *	This routine dumps out all non-default GUC options into a binary
   *	file that is read by all exec'ed backends.  The format is:
   *
   *		variable name, string, null terminated
   *		variable value, string, null terminated
   *		variable source, integer
   */
  void
  write_nondefault_variables(GucContext context)
  {
  	int			i;
  	int			elevel;
  	FILE	   *fp;
  
  	Assert(context == PGC_POSTMASTER || context == PGC_SIGHUP);
  
  	elevel = (context == PGC_SIGHUP) ? LOG : ERROR;
  
  	/*
  	 * Open file
  	 */
  	fp = AllocateFile(CONFIG_EXEC_PARAMS_NEW, "w");
  	if (!fp)
  	{
  		ereport(elevel,
  				(errcode_for_file_access(),
  				 errmsg("could not write to file \"%s\": %m",
  						CONFIG_EXEC_PARAMS_NEW)));
  		return;
  	}
  
  	for (i = 0; i < num_guc_variables; i++)
  	{
  		struct config_generic *gconf = guc_variables[i];
  
  		if (gconf->source != PGC_S_DEFAULT)
  		{
  			fprintf(fp, "%s", gconf->name);
  			fputc(0, fp);
  
  			switch (gconf->vartype)
  			{
  				case PGC_BOOL:
  					{
  						struct config_bool *conf = (struct config_bool *) gconf;
  
  						if (*conf->variable == 0)
  							fprintf(fp, "false");
  						else
  							fprintf(fp, "true");
  					}
  					break;
  
  				case PGC_INT:
  					{
  						struct config_int *conf = (struct config_int *) gconf;
  
  						fprintf(fp, "%d", *conf->variable);
  					}
  					break;
  
  				case PGC_REAL:
  					{
  						struct config_real *conf = (struct config_real *) gconf;
  
  						/* Could lose precision here? */
  						fprintf(fp, "%f", *conf->variable);
  					}
  					break;
  
  				case PGC_STRING:
  					{
  						struct config_string *conf = (struct config_string *) gconf;
  
  						fprintf(fp, "%s", *conf->variable);
  					}
  					break;
  			}
  
  			fputc(0, fp);
  
  			fwrite(&gconf->source, sizeof(gconf->source), 1, fp);
  		}
  	}
  
  	if (FreeFile(fp))
  	{
  		ereport(elevel,
  				(errcode_for_file_access(),
  				 errmsg("could not write to file \"%s\": %m",
  						CONFIG_EXEC_PARAMS_NEW)));
  		return;
  	}
  
  	/*
  	 * Put new file in place.  This could delay on Win32, but we don't hold
  	 * any exclusive locks.
  	 */
  	rename(CONFIG_EXEC_PARAMS_NEW, CONFIG_EXEC_PARAMS);
  }
  
  
  /*
   *	Read string, including null byte from file
   *
   *	Return NULL on EOF and nothing read
   */
  static char *
  read_string_with_null(FILE *fp)
  {
  	int			i = 0,
  				ch,
  				maxlen = 256;
  	char	   *str = NULL;
  
  	do
  	{
  		if ((ch = fgetc(fp)) == EOF)
  		{
  			if (i == 0)
  				return NULL;
  			else
  				elog(FATAL, "invalid format of exec config params file");
  		}
  		if (i == 0)
  			str = guc_malloc(FATAL, maxlen);
  		else if (i == maxlen)
  			str = guc_realloc(FATAL, str, maxlen *= 2);
  		str[i++] = ch;
  	} while (ch != 0);
  
  	return str;
  }
  
  
  /*
   *	This routine loads a previous postmaster dump of its non-default
   *	settings.
   */
  void
  read_nondefault_variables(void)
  {
  	FILE	   *fp;
  	char	   *varname,
  			   *varvalue;
  	int			varsource;
  
  	/*
  	 * Open file
  	 */
  	fp = AllocateFile(CONFIG_EXEC_PARAMS, "r");
  	if (!fp)
  	{
  		/* File not found is fine */
  		if (errno != ENOENT)
  			ereport(FATAL,
  					(errcode_for_file_access(),
  					 errmsg("could not read from file \"%s\": %m",
  							CONFIG_EXEC_PARAMS)));
  		return;
  	}
  
  	for (;;)
  	{
  		struct config_generic *record;
  
  		if ((varname = read_string_with_null(fp)) == NULL)
  			break;
  
  		if ((record = find_option(varname, true, FATAL)) == NULL)
  			elog(FATAL, "failed to locate variable %s in exec config params file", varname);
  		if ((varvalue = read_string_with_null(fp)) == NULL)
  			elog(FATAL, "invalid format of exec config params file");
  		if (fread(&varsource, sizeof(varsource), 1, fp) == 0)
  			elog(FATAL, "invalid format of exec config params file");
  
  		(void) set_config_option(varname, varvalue, record->context,
  								 varsource, GUC_ACTION_SET, true);
  		free(varname);
  		free(varvalue);
  	}
  
  	FreeFile(fp);
  }
  #endif   /* EXEC_BACKEND */
  
  
  /*
   * A little "long argument" simulation, although not quite GNU
   * compliant. Takes a string of the form "some-option=some value" and
   * returns name = "some_option" and value = "some value" in malloc'ed
   * storage. Note that '-' is converted to '_' in the option name. If
   * there is no '=' in the input string then value will be NULL.
   */
  void
  ParseLongOption(const char *string, char **name, char **value)
  {
  	size_t		equal_pos;
  	char	   *cp;
  
  	AssertArg(string);
  	AssertArg(name);
  	AssertArg(value);
  
  	equal_pos = strcspn(string, "=");
  
  	if (string[equal_pos] == '=')
  	{
  		*name = guc_malloc(FATAL, equal_pos + 1);
  		strlcpy(*name, string, equal_pos + 1);
  
  		*value = guc_strdup(FATAL, &string[equal_pos + 1]);
  	}
  	else
  	{
  		/* no equal sign in string */
  		*name = guc_strdup(FATAL, string);
  		*value = NULL;
  	}
  
  	for (cp = *name; *cp; cp++)
  		if (*cp == '-')
  			*cp = '_';
  }
  
  /*
   * Handle options fetched from pg_database.datconfig, pg_authid.rolconfig,
   * pg_proc.proconfig, etc.	Caller must specify proper context/source/action.
   *
   * The array parameter must be an array of TEXT (it must not be NULL).
   */
  void
  ProcessGUCArray(ArrayType *array,
  				GucContext context, GucSource source, GucAction action)
  {
  	int			i;
  
  	Assert(array != NULL);
  	Assert(ARR_ELEMTYPE(array) == TEXTOID);
  	Assert(ARR_NDIM(array) == 1);
  	Assert(ARR_LBOUND(array)[0] == 1);
  
  	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
  	{
  		Datum		d;
  		bool		isnull;
  		char	   *s;
  		char	   *name;
  		char	   *value;
  
  		d = array_ref(array, 1, &i,
  					  -1 /* varlenarray */ ,
  					  -1 /* TEXT's typlen */ ,
  					  false /* TEXT's typbyval */ ,
  					  'i' /* TEXT's typalign */ ,
  					  &isnull);
  
  		if (isnull)
  			continue;
  
  		s = DatumGetCString(DirectFunctionCall1(textout, d));
  
  		ParseLongOption(s, &name, &value);
  		if (!value)
  		{
  			ereport(WARNING,
  					(errcode(ERRCODE_SYNTAX_ERROR),
  					 errmsg("could not parse setting for parameter \"%s\"",
  							name)));
  			free(name);
  			continue;
  		}
  
  		(void) set_config_option(name, value, context, source, action, true);
  
  		free(name);
  		if (value)
  			free(value);
  		pfree(s);
  	}
  }
  
  
  /*
   * Add an entry to an option array.  The array parameter may be NULL
   * to indicate the current table entry is NULL.
   */
  ArrayType *
  GUCArrayAdd(ArrayType *array, const char *name, const char *value)
  {
  	const char *varname;
  	Datum		datum;
  	char	   *newval;
  	ArrayType  *a;
  
  	Assert(name);
  	Assert(value);
  
  	/* test if the option is valid */
  	set_config_option(name, value,
  					  superuser() ? PGC_SUSET : PGC_USERSET,
  					  PGC_S_TEST, GUC_ACTION_SET, false);
  
  	/* convert name to canonical spelling, so we can use plain strcmp */
  	(void) GetConfigOptionByName(name, &varname);
  	name = varname;
  
  	newval = palloc(strlen(name) + 1 + strlen(value) + 1);
  	sprintf(newval, "%s=%s", name, value);
  	datum = DirectFunctionCall1(textin, CStringGetDatum(newval));
  
  	if (array)
  	{
  		int			index;
  		bool		isnull;
  		int			i;
  
  		Assert(ARR_ELEMTYPE(array) == TEXTOID);
  		Assert(ARR_NDIM(array) == 1);
  		Assert(ARR_LBOUND(array)[0] == 1);
  
  		index = ARR_DIMS(array)[0] + 1; /* add after end */
  
  		for (i = 1; i <= ARR_DIMS(array)[0]; i++)
  		{
  			Datum		d;
  			char	   *current;
  
  			d = array_ref(array, 1, &i,
  						  -1 /* varlenarray */ ,
  						  -1 /* TEXT's typlen */ ,
  						  false /* TEXT's typbyval */ ,
  						  'i' /* TEXT's typalign */ ,
  						  &isnull);
  			if (isnull)
  				continue;
  			current = DatumGetCString(DirectFunctionCall1(textout, d));
  			if (strncmp(current, newval, strlen(name) + 1) == 0)
  			{
  				index = i;
  				break;
  			}
  		}
  
  		a = array_set(array, 1, &index,
  					  datum,
  					  false,
  					  -1 /* varlena array */ ,
  					  -1 /* TEXT's typlen */ ,
  					  false /* TEXT's typbyval */ ,
  					  'i' /* TEXT's typalign */ );
  	}
  	else
  		a = construct_array(&datum, 1,
  							TEXTOID,
  							-1, false, 'i');
  
  	return a;
  }
  
  
  /*
   * Delete an entry from an option array.  The array parameter may be NULL
   * to indicate the current table entry is NULL.  Also, if the return value
   * is NULL then a null should be stored.
   */
  ArrayType *
  GUCArrayDelete(ArrayType *array, const char *name)
  {
  	const char *varname;
  	ArrayType  *newarray;
  	int			i;
  	int			index;
  
  	Assert(name);
  
  	/* test if the option is valid */
  	set_config_option(name, NULL,
  					  superuser() ? PGC_SUSET : PGC_USERSET,
  					  PGC_S_TEST, GUC_ACTION_SET, false);
  
  	/* convert name to canonical spelling, so we can use plain strcmp */
  	(void) GetConfigOptionByName(name, &varname);
  	name = varname;
  
  	/* if array is currently null, then surely nothing to delete */
  	if (!array)
  		return NULL;
  
  	newarray = NULL;
  	index = 1;
  
  	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
  	{
  		Datum		d;
  		char	   *val;
  		bool		isnull;
  
  		d = array_ref(array, 1, &i,
  					  -1 /* varlenarray */ ,
  					  -1 /* TEXT's typlen */ ,
  					  false /* TEXT's typbyval */ ,
  					  'i' /* TEXT's typalign */ ,
  					  &isnull);
  		if (isnull)
  			continue;
  		val = DatumGetCString(DirectFunctionCall1(textout, d));
  
  		/* ignore entry if it's what we want to delete */
  		if (strncmp(val, name, strlen(name)) == 0
  			&& val[strlen(name)] == '=')
  			continue;
  
  
  		/* else add it to the output array */
  		if (newarray)
  		{
  			newarray = array_set(newarray, 1, &index,
  								 d,
  								 false,
  								 -1 /* varlenarray */ ,
  								 -1 /* TEXT's typlen */ ,
  								 false /* TEXT's typbyval */ ,
  								 'i' /* TEXT's typalign */ );
  		}
  		else
  			newarray = construct_array(&d, 1,
  									   TEXTOID,
  									   -1, false, 'i');
  
  		index++;
  	}
  
  	return newarray;
  }
  
  /*
   * Given a GUC array, delete all settings from it that our permission
   * level allows: if superuser, delete them all; if regular user, only
   * those that are PGC_USERSET
   */
  ArrayType *
  GUCArrayReset(ArrayType *array)
  {
  	ArrayType  *newarray;
  	int			i;
  	int			index;
  
  	/* if array is currently null, nothing to do */
  	if (!array)
  		return NULL;
  
  	/* if we're superuser, we can delete everything */
  	if (superuser())
  		return NULL;
  
  	newarray = NULL;
  	index = 1;
  
  	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
  	{
  		Datum		d;
  		char	   *val;
  		char	   *eqsgn;
  		bool		isnull;
  		struct config_generic *gconf;
  
  		d = array_ref(array, 1, &i,
  					  -1 /* varlenarray */ ,
  					  -1 /* TEXT's typlen */ ,
  					  false /* TEXT's typbyval */ ,
  					  'i' /* TEXT's typalign */ ,
  					  &isnull);
  
  		if (isnull)
  			continue;
  		val = DatumGetCString(DirectFunctionCall1(textout, d));
  
  		eqsgn = strchr(val, '=');
  		*eqsgn = '\0';
  
  		gconf = find_option(val, false, WARNING);
  		if (!gconf)
  			continue;
  
  		/* note: superuser-ness was already checked above */
  		/* skip entry if OK to delete */
  		if (gconf->context == PGC_USERSET)
  			continue;
  
  		/* XXX do we need to worry about database owner? */
  
  		/* else add it to the output array */
  		if (newarray)
  		{
  			newarray = array_set(newarray, 1, &index,
  								 d,
  								 false,
  								 -1 /* varlenarray */ ,
  								 -1 /* TEXT's typlen */ ,
  								 false /* TEXT's typbyval */ ,
  								 'i' /* TEXT's typalign */ );
  		}
  		else
  			newarray = construct_array(&d, 1,
  									   TEXTOID,
  									   -1, false, 'i');
  
  		index++;
  		pfree(val);
  	}
  
  	return newarray;
  }
  
  /*
   * assign_hook and show_hook subroutines
   */
  
  static const char *
  assign_log_destination(const char *value, bool doit, GucSource source)
  {
  	char	   *rawstring;
  	List	   *elemlist;
  	ListCell   *l;
  	int			newlogdest = 0;
  
  	/* Need a modifiable copy of string */
  	rawstring = pstrdup(value);
  
  	/* Parse string into list of identifiers */
  	if (!SplitIdentifierString(rawstring, ',', &elemlist))
  	{
  		/* syntax error in list */
  		pfree(rawstring);
  		list_free(elemlist);
  		ereport(GUC_complaint_elevel(source),
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  			errmsg("invalid list syntax for parameter \"log_destination\"")));
  		return NULL;
  	}
  
  	foreach(l, elemlist)
  	{
  		char	   *tok = (char *) lfirst(l);
  
  		if (pg_strcasecmp(tok, "stderr") == 0)
  			newlogdest |= LOG_DESTINATION_STDERR;
  		else if (pg_strcasecmp(tok, "csvlog") == 0)
  			newlogdest |= LOG_DESTINATION_CSVLOG;
  #ifdef HAVE_SYSLOG
  		else if (pg_strcasecmp(tok, "syslog") == 0)
  			newlogdest |= LOG_DESTINATION_SYSLOG;
  #endif
  #ifdef WIN32
  		else if (pg_strcasecmp(tok, "eventlog") == 0)
  			newlogdest |= LOG_DESTINATION_EVENTLOG;
  #endif
  		else
  		{
  			ereport(GUC_complaint_elevel(source),
  					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				  errmsg("unrecognized \"log_destination\" key word: \"%s\"",
  						 tok)));
  			pfree(rawstring);
  			list_free(elemlist);
  			return NULL;
  		}
  	}
  
  	if (doit)
  		Log_destination = newlogdest;
  
  	pfree(rawstring);
  	list_free(elemlist);
  
  	return value;
  }
  
  #ifdef HAVE_SYSLOG
  
  static const char *
  assign_syslog_facility(const char *facility, bool doit, GucSource source)
  {
  	int			syslog_fac;
  
  	if (pg_strcasecmp(facility, "LOCAL0") == 0)
  		syslog_fac = LOG_LOCAL0;
  	else if (pg_strcasecmp(facility, "LOCAL1") == 0)
  		syslog_fac = LOG_LOCAL1;
  	else if (pg_strcasecmp(facility, "LOCAL2") == 0)
  		syslog_fac = LOG_LOCAL2;
  	else if (pg_strcasecmp(facility, "LOCAL3") == 0)
  		syslog_fac = LOG_LOCAL3;
  	else if (pg_strcasecmp(facility, "LOCAL4") == 0)
  		syslog_fac = LOG_LOCAL4;
  	else if (pg_strcasecmp(facility, "LOCAL5") == 0)
  		syslog_fac = LOG_LOCAL5;
  	else if (pg_strcasecmp(facility, "LOCAL6") == 0)
  		syslog_fac = LOG_LOCAL6;
  	else if (pg_strcasecmp(facility, "LOCAL7") == 0)
  		syslog_fac = LOG_LOCAL7;
  	else
  		return NULL;			/* reject */
  
  	if (doit)
  	{
  		syslog_facility = syslog_fac;
  		set_syslog_parameters(syslog_ident_str ? syslog_ident_str : "postgres",
  							  syslog_facility);
  	}
  
  	return facility;
  }
  
  static const char *
  assign_syslog_ident(const char *ident, bool doit, GucSource source)
  {
  	if (doit)
  		set_syslog_parameters(ident, syslog_facility);
  
  	return ident;
  }
  #endif   /* HAVE_SYSLOG */
  
  
  static const char *
  assign_defaultxactisolevel(const char *newval, bool doit, GucSource source)
  {
  	if (pg_strcasecmp(newval, "serializable") == 0)
  	{
  		if (doit)
  			DefaultXactIsoLevel = XACT_SERIALIZABLE;
  	}
  	else if (pg_strcasecmp(newval, "repeatable read") == 0)
  	{
  		if (doit)
  			DefaultXactIsoLevel = XACT_REPEATABLE_READ;
  	}
  	else if (pg_strcasecmp(newval, "read committed") == 0)
  	{
  		if (doit)
  			DefaultXactIsoLevel = XACT_READ_COMMITTED;
  	}
  	else if (pg_strcasecmp(newval, "read uncommitted") == 0)
  	{
  		if (doit)
  			DefaultXactIsoLevel = XACT_READ_UNCOMMITTED;
  	}
  	else
  		return NULL;
  	return newval;
  }
  
  static const char *
  assign_session_replication_role(const char *newval, bool doit, GucSource source)
  {
  	int			newrole;
  
  	if (pg_strcasecmp(newval, "origin") == 0)
  		newrole = SESSION_REPLICATION_ROLE_ORIGIN;
  	else if (pg_strcasecmp(newval, "replica") == 0)
  		newrole = SESSION_REPLICATION_ROLE_REPLICA;
  	else if (pg_strcasecmp(newval, "local") == 0)
  		newrole = SESSION_REPLICATION_ROLE_LOCAL;
  	else
  		return NULL;
  
  	/*
  	 * Must flush the plan cache when changing replication role; but don't
  	 * flush unnecessarily.
  	 */
  	if (doit && SessionReplicationRole != newrole)
  	{
  		ResetPlanCache();
  		SessionReplicationRole = newrole;
  	}
  
  	return newval;
  }
  
  static const char *
  assign_log_min_messages(const char *newval, bool doit, GucSource source)
  {
  	return (assign_msglvl(&log_min_messages, newval, doit, source));
  }
  
  static const char *
  assign_client_min_messages(const char *newval, bool doit, GucSource source)
  {
  	return (assign_msglvl(&client_min_messages, newval, doit, source));
  }
  
  static const char *
  assign_min_error_statement(const char *newval, bool doit, GucSource source)
  {
  	return (assign_msglvl(&log_min_error_statement, newval, doit, source));
  }
  
  const char *
  assign_msglvl(int *var, const char *newval, bool doit, GucSource source)
  {
  	if (pg_strcasecmp(newval, "debug") == 0)
  	{
  		if (doit)
  			(*var) = DEBUG2;
  	}
  	else if (pg_strcasecmp(newval, "debug5") == 0)
  	{
  		if (doit)
  			(*var) = DEBUG5;
  	}
  	else if (pg_strcasecmp(newval, "debug4") == 0)
  	{
  		if (doit)
  			(*var) = DEBUG4;
  	}
  	else if (pg_strcasecmp(newval, "debug3") == 0)
  	{
  		if (doit)
  			(*var) = DEBUG3;
  	}
  	else if (pg_strcasecmp(newval, "debug2") == 0)
  	{
  		if (doit)
  			(*var) = DEBUG2;
  	}
  	else if (pg_strcasecmp(newval, "debug1") == 0)
  	{
  		if (doit)
  			(*var) = DEBUG1;
  	}
  	else if (pg_strcasecmp(newval, "log") == 0)
  	{
  		if (doit)
  			(*var) = LOG;
  	}
  
  	/*
  	 * Client_min_messages always prints 'info', but we allow it as a value
  	 * anyway.
  	 */
  	else if (pg_strcasecmp(newval, "info") == 0)
  	{
  		if (doit)
  			(*var) = INFO;
  	}
  	else if (pg_strcasecmp(newval, "notice") == 0)
  	{
  		if (doit)
  			(*var) = NOTICE;
  	}
  	else if (pg_strcasecmp(newval, "warning") == 0)
  	{
  		if (doit)
  			(*var) = WARNING;
  	}
  	else if (pg_strcasecmp(newval, "error") == 0)
  	{
  		if (doit)
  			(*var) = ERROR;
  	}
  	/* We allow FATAL/PANIC for client-side messages too. */
  	else if (pg_strcasecmp(newval, "fatal") == 0)
  	{
  		if (doit)
  			(*var) = FATAL;
  	}
  	else if (pg_strcasecmp(newval, "panic") == 0)
  	{
  		if (doit)
  			(*var) = PANIC;
  	}
  	else
  		return NULL;			/* fail */
  	return newval;				/* OK */
  }
  
  static const char *
  assign_IntervalStyle(const char *newval, bool doit, GucSource source)
  {
  	if (pg_strcasecmp(newval, "postgres")==0)
  	{
  		if (doit)
  			IntervalStyle = INTSTYLE_POSTGRES;
  	}
  	else if (pg_strcasecmp(newval, "postgres_verbose")==0)
  	{
  		if (doit)
  			IntervalStyle = INTSTYLE_POSTGRES_VERBOSE;
  	}
  	else if (pg_strcasecmp(newval, "sql_standard")==0)
  	{
  		if (doit)
  			IntervalStyle = INTSTYLE_SQL_STANDARD;
  	}
  	else if (pg_strcasecmp(newval, "ISO_8601")==0)
  	{
  		if (doit)
  			IntervalStyle = INTSTYLE_ISO_8601;
  	}
  	else
  		return NULL;
  	return newval;
  
  }
  
  static const char *
  show_IntervalStyle(void)
  {
  	switch(IntervalStyle)
  	{
  	case INTSTYLE_POSTGRES:  return "postgres";
  	case INTSTYLE_POSTGRES_VERBOSE:  return "postgres_verbose";
  	case INTSTYLE_SQL_STANDARD:  return "sql_standard";
  	case INTSTYLE_ISO_8601:  return "ISO_8601";
  	};
  	return NULL;
  
  }
  
  static const char *
  assign_log_error_verbosity(const char *newval, bool doit, GucSource source)
  {
  	if (pg_strcasecmp(newval, "terse") == 0)
  	{
  		if (doit)
  			Log_error_verbosity = PGERROR_TERSE;
  	}
  	else if (pg_strcasecmp(newval, "default") == 0)
  	{
  		if (doit)
  			Log_error_verbosity = PGERROR_DEFAULT;
  	}
  	else if (pg_strcasecmp(newval, "verbose") == 0)
  	{
  		if (doit)
  			Log_error_verbosity = PGERROR_VERBOSE;
  	}
  	else
  		return NULL;			/* fail */
  	return newval;				/* OK */
  }
  
  static const char *
  assign_log_statement(const char *newval, bool doit, GucSource source)
  {
  	if (pg_strcasecmp(newval, "none") == 0)
  	{
  		if (doit)
  			log_statement = LOGSTMT_NONE;
  	}
  	else if (pg_strcasecmp(newval, "ddl") == 0)
  	{
  		if (doit)
  			log_statement = LOGSTMT_DDL;
  	}
  	else if (pg_strcasecmp(newval, "mod") == 0)
  	{
  		if (doit)
  			log_statement = LOGSTMT_MOD;
  	}
  	else if (pg_strcasecmp(newval, "all") == 0)
  	{
  		if (doit)
  			log_statement = LOGSTMT_ALL;
  	}
  	else
  		return NULL;			/* fail */
  	return newval;				/* OK */
  }
  
  static const char *
  show_num_temp_buffers(void)
  {
  	/*
  	 * We show the GUC var until local buffers have been initialized, and
  	 * NLocBuffer afterwards.
  	 */
  	static char nbuf[32];
  
  	sprintf(nbuf, "%d", NLocBuffer ? NLocBuffer : num_temp_buffers);
  	return nbuf;
  }
  
  static bool
  assign_phony_autocommit(bool newval, bool doit, GucSource source)
  {
  	if (!newval)
  	{
  		ereport(GUC_complaint_elevel(source),
  				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  				 errmsg("SET AUTOCOMMIT TO OFF is no longer supported")));
  		return false;
  	}
  	return true;
  }
  
  static const char *
  assign_custom_variable_classes(const char *newval, bool doit, GucSource source)
  {
  	/*
  	 * Check syntax. newval must be a comma separated list of identifiers.
  	 * Whitespace is allowed but removed from the result.
  	 */
  	bool		hasSpaceAfterToken = false;
  	const char *cp = newval;
  	int			symLen = 0;
  	char		c;
  	StringInfoData buf;
  
  	initStringInfo(&buf);
  	while ((c = *cp++) != '\0')
  	{
  		if (isspace((unsigned char) c))
  		{
  			if (symLen > 0)
  				hasSpaceAfterToken = true;
  			continue;
  		}
  
  		if (c == ',')
  		{
  			if (symLen > 0)		/* terminate identifier */
  			{
  				appendStringInfoChar(&buf, ',');
  				symLen = 0;
  			}
  			hasSpaceAfterToken = false;
  			continue;
  		}
  
  		if (hasSpaceAfterToken || !isalnum((unsigned char) c))
  		{
  			/*
  			 * Syntax error due to token following space after token or non
  			 * alpha numeric character
  			 */
  			pfree(buf.data);
  			return NULL;
  		}
  		appendStringInfoChar(&buf, c);
  		symLen++;
  	}
  
  	/* Remove stray ',' at end */
  	if (symLen == 0 && buf.len > 0)
  		buf.data[--buf.len] = '\0';
  
  	/* GUC wants the result malloc'd */
  	newval = guc_strdup(LOG, buf.data);
  
  	pfree(buf.data);
  	return newval;
  }
  
  static bool
  assign_debug_assertions(bool newval, bool doit, GucSource source)
  {
  #ifndef USE_ASSERT_CHECKING
  	if (newval)
  	{
  		ereport(GUC_complaint_elevel(source),
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  			   errmsg("assertion checking is not supported by this build")));
  		return false;
  	}
  #endif
  	return true;
  }
  
  static bool
  assign_ssl(bool newval, bool doit, GucSource source)
  {
  #ifndef USE_SSL
  	if (newval)
  	{
  		ereport(GUC_complaint_elevel(source),
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("SSL is not supported by this build")));
  		return false;
  	}
  #endif
  	return true;
  }
  
  static bool
  assign_stage_log_stats(bool newval, bool doit, GucSource source)
  {
  	if (newval && log_statement_stats)
  	{
  		ereport(GUC_complaint_elevel(source),
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("cannot enable parameter when \"log_statement_stats\" is true")));
  		/* source == PGC_S_OVERRIDE means do it anyway, eg at xact abort */
  		if (source != PGC_S_OVERRIDE)
  			return false;
  	}
  	return true;
  }
  
  static bool
  assign_log_stats(bool newval, bool doit, GucSource source)
  {
  	if (newval &&
  		(log_parser_stats || log_planner_stats || log_executor_stats || log_dispatch_stats))
  	{
  		ereport(GUC_complaint_elevel(source),
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("cannot enable \"log_statement_stats\" when "
  						"\"log_parser_stats\", \"log_planner_stats\", "
  						"\"log_dispatch_stats\", "
  						"or \"log_executor_stats\" is true")));
  		/* source == PGC_S_OVERRIDE means do it anyway, eg at xact abort */
  		if (source != PGC_S_OVERRIDE)
  			return false;
  	}
  	return true;
  }
  
  static bool
  assign_transaction_read_only(bool newval, bool doit, GucSource source)
  {
  	/* Can't go to r/w mode inside a r/o transaction */
  	if (newval == false && XactReadOnly && IsSubTransaction())
  	{
  		ereport(GUC_complaint_elevel(source),
  				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  				 errmsg("cannot set transaction read-write mode inside a read-only transaction")));
  		/* source == PGC_S_OVERRIDE means do it anyway, eg at xact abort */
  		if (source != PGC_S_OVERRIDE)
  			return false;
  	}
  	return true;
  }
  
  static const char *
  assign_canonical_path(const char *newval, bool doit, GucSource source)
  {
  	if (doit)
  	{
  		char	   *canon_val = guc_strdup(ERROR, newval);
  
  		canonicalize_path(canon_val);
  		return canon_val;
  	}
  	else
  		return newval;
  }
  
  static const char *
  assign_backslash_quote(const char *newval, bool doit, GucSource source)
  {
  	BackslashQuoteType bq;
  	bool		bqbool;
  
  	/*
  	 * Although only "on", "off", and "safe_encoding" are documented, we use
  	 * parse_bool so we can accept all the likely variants of "on" and "off".
  	 */
  	if (pg_strcasecmp(newval, "safe_encoding") == 0)
  		bq = BACKSLASH_QUOTE_SAFE_ENCODING;
  	else if (parse_bool(newval, &bqbool))
  	{
  		bq = bqbool ? BACKSLASH_QUOTE_ON : BACKSLASH_QUOTE_OFF;
  	}
  	else
  		return NULL;			/* reject */
  
  	if (doit)
  		backslash_quote = bq;
  
  	return newval;
  }
  
  static const char *
  assign_timezone_abbreviations(const char *newval, bool doit, GucSource source)
  {
  	/*
  	 * The powerup value shown above for timezone_abbreviations is "UNKNOWN".
  	 * When we see this we just do nothing.  If this value isn't overridden
  	 * from the config file then pg_timezone_abbrev_initialize() will
  	 * eventually replace it with "Default".  This hack has two purposes: to
  	 * avoid wasting cycles loading values that might soon be overridden from
  	 * the config file, and to avoid trying to read the timezone abbrev files
  	 * during InitializeGUCOptions().  The latter doesn't work in an
  	 * EXEC_BACKEND subprocess because my_exec_path hasn't been set yet and so
  	 * we can't locate PGSHAREDIR.  (Essentially the same hack is used to
  	 * delay initializing TimeZone ... if we have any more, we should try to
  	 * clean up and centralize this mechanism ...)
  	 */
  	if (strcmp(newval, "UNKNOWN") == 0)
  	{
  		return newval;
  	}
  
  	/* Loading abbrev file is expensive, so only do it when value changes */
  	if (timezone_abbreviations_string == NULL ||
  		strcmp(timezone_abbreviations_string, newval) != 0)
  	{
  		int			elevel;
  
  		/*
  		 * If reading config file, only the postmaster should bleat loudly
  		 * about problems.	Otherwise, it's just this one process doing it,
  		 * and we use WARNING message level.
  		 */
  		if (source == PGC_S_FILE)
  			elevel = IsUnderPostmaster ? DEBUG3 : LOG;
  		else
  			elevel = WARNING;
  		if (!load_tzoffsets(newval, doit, elevel))
  			return NULL;
  	}
  	return newval;
  }
  
  /*
   * pg_timezone_abbrev_initialize --- set default value if not done already
   *
   * This is called after initial loading of postgresql.conf.  If no
   * timezone_abbreviations setting was found therein, select default.
   */
  void
  pg_timezone_abbrev_initialize(void)
  {
  	if (strcmp(timezone_abbreviations_string, "UNKNOWN") == 0)
  	{
  		SetConfigOption("timezone_abbreviations", "Default",
  						PGC_POSTMASTER, PGC_S_ARGV);
  	}
  }
  
  static const char *
  assign_xmlbinary(const char *newval, bool doit, GucSource source)
  {
  	XmlBinaryType xb;
  
  	if (pg_strcasecmp(newval, "base64") == 0)
  		xb = XMLBINARY_BASE64;
  	else if (pg_strcasecmp(newval, "hex") == 0)
  		xb = XMLBINARY_HEX;
  	else
  		return NULL;			/* reject */
  
  	if (doit)
  		xmlbinary = xb;
  
  	return newval;
  }
  
  static const char *
  assign_xmloption(const char *newval, bool doit, GucSource source)
  {
  	XmlOptionType xo;
  
  	if (pg_strcasecmp(newval, "document") == 0)
  		xo = XMLOPTION_DOCUMENT;
  	else if (pg_strcasecmp(newval, "content") == 0)
  		xo = XMLOPTION_CONTENT;
  	else
  		return NULL;			/* reject */
  
  	if (doit)
  		xmloption = xo;
  
  	return newval;
  }
  
  static const char *
  show_archive_command(void)
  {
  	if (XLogArchiveMode)
  		return XLogArchiveCommand;
  	else
  		return "(disabled)";
  }
  
  static bool
  assign_tcp_keepalives_idle(int newval, bool doit, GucSource source)
  {
  	if (doit)
  		return (pq_setkeepalivesidle(newval, MyProcPort) == STATUS_OK);
  
  	return true;
  }
  
  static const char *
  show_tcp_keepalives_idle(void)
  {
  	static char nbuf[16];
  
  	snprintf(nbuf, sizeof(nbuf), "%d", pq_getkeepalivesidle(MyProcPort));
  	return nbuf;
  }
  
  static bool
  assign_tcp_keepalives_interval(int newval, bool doit, GucSource source)
  {
  	if (doit)
  		return (pq_setkeepalivesinterval(newval, MyProcPort) == STATUS_OK);
  
  	return true;
  }
  
  static const char *
  show_tcp_keepalives_interval(void)
  {
  	static char nbuf[16];
  
  	snprintf(nbuf, sizeof(nbuf), "%d", pq_getkeepalivesinterval(MyProcPort));
  	return nbuf;
  }
  
  static bool
  assign_tcp_keepalives_count(int newval, bool doit, GucSource source)
  {
  	if (doit)
  		return (pq_setkeepalivescount(newval, MyProcPort) == STATUS_OK);
  
  	return true;
  }
  
  static const char *
  show_tcp_keepalives_count(void)
  {
  	static char nbuf[16];
  
  	snprintf(nbuf, sizeof(nbuf), "%d", pq_getkeepalivescount(MyProcPort));
  	return nbuf;
  }
  
  static const char *
  assign_pgstat_temp_directory(const char *newval, bool doit, GucSource source)
  {
  	if (doit)
  	{
  		char	   *canon_val = guc_strdup(ERROR, newval);
  		char	   *tname;
  		char	   *fname;
  
  		canonicalize_path(canon_val);
  
  		tname = guc_malloc(ERROR, strlen(canon_val) + 12);		/* /pgstat.tmp */
  		sprintf(tname, "%s/pgstat.tmp", canon_val);
  		fname = guc_malloc(ERROR, strlen(canon_val) + 13);		/* /pgstat.stat */
  		sprintf(fname, "%s/pgstat.stat", canon_val);
  
  		if (pgstat_stat_tmpname)
  			free(pgstat_stat_tmpname);
  		pgstat_stat_tmpname = tname;
  		if (pgstat_stat_filename)
  			free(pgstat_stat_filename);
  		pgstat_stat_filename = fname;
  
  		return canon_val;
  	}
  	else
  		return newval;
  }
  
  
  static const char *
  assign_application_name(const char *newval, bool doit, GucSource source)
  {
  	if (doit)
  	{
  		/* Only allow clean ASCII chars in the application name */
  		char	   *repval = guc_strdup(ERROR, newval);
  		char	   *p;
  
  		for (p = repval; *p; p++)
  		{
  			if (*p < 32 || *p > 126)
  				*p = '?';
  		}
  
  		/* Update the pg_stat_activity view */
  		pgstat_report_appname(repval);
  
  		return repval;
  	}
  	else
  		return newval;
  }
  
  /*
   * Assign hook routine for "allow_system_table_mods" GUC.
   * Setting it DDL or ALL requires either:
   * 		- upgrade_mode GUC set
   * 		- in single user mode
   */
  static const char *
  assign_allow_system_table_mods(const char *newval,
  							   bool doit,
  							   GucSource source)
  {
  	bool valueDDL = false;
  	bool valueDML = false;
  
  	if (newval == NULL || newval[0] == 0 ||
  		!pg_strcasecmp("none", newval));
  	else if (!pg_strcasecmp("dml", newval))
  		valueDML = true;
  	else if (!pg_strcasecmp("ddl", newval) && !IsUnderPostmaster)
  		valueDDL = true;
  	else if (!pg_strcasecmp("all", newval) && !IsUnderPostmaster)
  	{
  		valueDML = true;
  		valueDDL = true;
  	}
  	else
  	{
  		if (source >= PGC_S_INTERACTIVE)
  			ereport(ERROR,
  					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
  					 errmsg("Unknown system table modification policy. (Current policy: '%s')",
  						show_allow_system_table_mods())));
  
  		return NULL;
  	}
  
  	if (doit)
  	{
  		allowSystemTableModsDML = valueDML;
  		allowSystemTableModsDDL = valueDDL;
  	}
  
  	return newval;
  }
  
  static const char *
  show_allow_system_table_mods(void)
  {
  	if (allowSystemTableModsDML && allowSystemTableModsDDL)
  		return "ALL";
  	else if (allowSystemTableModsDDL)
  		return "DDL";
  	else if (allowSystemTableModsDML)
  		return "DML";
  	else
  		return "NONE";
  }
  
  static bool
  assign_maxconnections(int newval, bool doit, GucSource source)
  {
  	if (newval + autovacuum_max_workers > INT_MAX / 4)
  		return false;
  
  	if (doit)
  		MaxBackends = newval + autovacuum_max_workers;
  
  	return true;
  }
  
  static bool
  assign_autovacuum_max_workers(int newval, bool doit, GucSource source)
  {
  	if (newval + MaxConnections > INT_MAX / 4)
  		return false;
  
  	if (doit)
  		MaxBackends = newval + MaxConnections;
  
  	return true;
  }
  
  #include "guc-file.c"
  