text: /*-------------------------------------------------------------------------
   *
   * execnodes.h
   *	  definitions for executor state nodes
   *
   *
   * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   * src/include/nodes/execnodes.h
   *
   *-------------------------------------------------------------------------
   */
  #ifndef EXECNODES_H
  #define EXECNODES_H
  
  #include "access/genam.h"
  #include "access/heapam.h"
  #include "access/skey.h"
  #include "nodes/params.h"
  #include "nodes/plannodes.h"
  #include "nodes/tidbitmap.h"
  #include "utils/hsearch.h"
  #include "utils/rel.h"
  #include "utils/snapshot.h"
  #include "utils/tuplestore.h"
  
  
  /* ----------------
   *	  IndexInfo information
   *
   *		this struct holds the information needed to construct new index
   *		entries for a particular index.  Used for both index_build and
   *		retail creation of index entries.
   *
   *		NumIndexAttrs		number of columns in this index
   *		KeyAttrNumbers		underlying-rel attribute numbers used as keys
   *							(zeroes indicate expressions)
   *		Expressions			expr trees for expression entries, or NIL if none
   *		ExpressionsState	exec state for expressions, or NIL if none
   *		Predicate			partial-index predicate, or NIL if none
   *		PredicateState		exec state for predicate, or NIL if none
   *		ExclusionOps		Per-column exclusion operators, or NULL if none
   *		ExclusionProcs		Underlying function OIDs for ExclusionOps
   *		ExclusionStrats		Opclass strategy numbers for ExclusionOps
   *		Unique				is it a unique index?
   *		ReadyForInserts		is it valid for inserts?
   *		Concurrent			are we doing a concurrent index build?
   *		BrokenHotChain		did we detect any broken HOT chains?
   *
   * ii_Concurrent and ii_BrokenHotChain are used only during index build;
   * they're conventionally set to false otherwise.
   * ----------------
   */
  typedef struct IndexInfo
  {
  	NodeTag		type;
  	int			ii_NumIndexAttrs;
  	AttrNumber	ii_KeyAttrNumbers[INDEX_MAX_KEYS];
  	List	   *ii_Expressions; /* list of Expr */
  	List	   *ii_ExpressionsState;	/* list of ExprState */
  	List	   *ii_Predicate;	/* list of Expr */
  	List	   *ii_PredicateState;		/* list of ExprState */
  	Oid		   *ii_ExclusionOps;	/* array with one entry per column */
  	Oid		   *ii_ExclusionProcs;		/* array with one entry per column */
  	uint16	   *ii_ExclusionStrats;		/* array with one entry per column */
  	bool		ii_Unique;
  	bool		ii_ReadyForInserts;
  	bool		ii_Concurrent;
  	bool		ii_BrokenHotChain;
  } IndexInfo;
  
  /* ----------------
   *	  ExprContext_CB
   *
   *		List of callbacks to be called at ExprContext shutdown.
   * ----------------
   */
  typedef void (*ExprContextCallbackFunction) (Datum arg);
  
  typedef struct ExprContext_CB
  {
  	struct ExprContext_CB *next;
  	ExprContextCallbackFunction function;
  	Datum		arg;
  } ExprContext_CB;
  
  /* ----------------
   *	  ExprContext
   *
   *		This class holds the "current context" information
   *		needed to evaluate expressions for doing tuple qualifications
   *		and tuple projections.	For example, if an expression refers
   *		to an attribute in the current inner tuple then we need to know
   *		what the current inner tuple is and so we look at the expression
   *		context.
   *
   *	There are two memory contexts associated with an ExprContext:
   *	* ecxt_per_query_memory is a query-lifespan context, typically the same
   *	  context the ExprContext node itself is allocated in.	This context
   *	  can be used for purposes such as storing function call cache info.
   *	* ecxt_per_tuple_memory is a short-term context for expression results.
   *	  As the name suggests, it will typically be reset once per tuple,
   *	  before we begin to evaluate expressions for that tuple.  Each
   *	  ExprContext normally has its very own per-tuple memory context.
   *
   *	CurrentMemoryContext should be set to ecxt_per_tuple_memory before
   *	calling ExecEvalExpr() --- see ExecEvalExprSwitchContext().
   * ----------------
   */
  typedef struct ExprContext
  {
  	NodeTag		type;
  
  	/* Tuples that Var nodes in expression may refer to */
  	TupleTableSlot *ecxt_scantuple;
  	TupleTableSlot *ecxt_innertuple;
  	TupleTableSlot *ecxt_outertuple;
  
  	/* Memory contexts for expression evaluation --- see notes above */
  	MemoryContext ecxt_per_query_memory;
  	MemoryContext ecxt_per_tuple_memory;
  
  	/* Values to substitute for Param nodes in expression */
  	ParamExecData *ecxt_param_exec_vals;		/* for PARAM_EXEC params */
  	ParamListInfo ecxt_param_list_info; /* for other param types */
  
  	/*
  	 * Values to substitute for Aggref nodes in the expressions of an Agg
  	 * node, or for WindowFunc nodes within a WindowAgg node.
  	 */
  	Datum	   *ecxt_aggvalues; /* precomputed values for aggs/windowfuncs */
  	bool	   *ecxt_aggnulls;	/* null flags for aggs/windowfuncs */
  
  	/* Value to substitute for CaseTestExpr nodes in expression */
  	Datum		caseValue_datum;
  	bool		caseValue_isNull;
  
  	/* Value to substitute for CoerceToDomainValue nodes in expression */
  	Datum		domainValue_datum;
  	bool		domainValue_isNull;
  
  	/* Link to containing EState (NULL if a standalone ExprContext) */
  	struct EState *ecxt_estate;
  
  	/* Functions to call back when ExprContext is shut down */
  	ExprContext_CB *ecxt_callbacks;
  } ExprContext;
  
  /*
   * Set-result status returned by ExecEvalExpr()
   */
  typedef enum
  {
  	ExprSingleResult,			/* expression does not return a set */
  	ExprMultipleResult,			/* this result is an element of a set */
  	ExprEndResult				/* there are no more elements in the set */
  } ExprDoneCond;
  
  /*
   * Return modes for functions returning sets.  Note values must be chosen
   * as separate bits so that a bitmask can be formed to indicate supported
   * modes.  SFRM_Materialize_Random and SFRM_Materialize_Preferred are
   * auxiliary flags about SFRM_Materialize mode, rather than separate modes.
   */
  typedef enum
  {
  	SFRM_ValuePerCall = 0x01,	/* one value returned per call */
  	SFRM_Materialize = 0x02,	/* result set instantiated in Tuplestore */
  	SFRM_Materialize_Random = 0x04,		/* Tuplestore needs randomAccess */
  	SFRM_Materialize_Preferred = 0x08	/* caller prefers Tuplestore */
  } SetFunctionReturnMode;
  
  /*
   * When calling a function that might return a set (multiple rows),
   * a node of this type is passed as fcinfo->resultinfo to allow
   * return status to be passed back.  A function returning set should
   * raise an error if no such resultinfo is provided.
   */
  typedef struct ReturnSetInfo
  {
  	NodeTag		type;
  	/* values set by caller: */
  	ExprContext *econtext;		/* context function is being called in */
  	TupleDesc	expectedDesc;	/* tuple descriptor expected by caller */
  	int			allowedModes;	/* bitmask: return modes caller can handle */
  	/* result status from function (but pre-initialized by caller): */
  	SetFunctionReturnMode returnMode;	/* actual return mode */
  	ExprDoneCond isDone;		/* status for ValuePerCall mode */
  	/* fields filled by function in Materialize return mode: */
  	Tuplestorestate *setResult; /* holds the complete returned tuple set */
  	TupleDesc	setDesc;		/* actual descriptor for returned tuples */
  } ReturnSetInfo;
  
  /* ----------------
   *		ProjectionInfo node information
   *
   *		This is all the information needed to perform projections ---
   *		that is, form new tuples by evaluation of targetlist expressions.
   *		Nodes which need to do projections create one of these.
   *
   *		ExecProject() evaluates the tlist, forms a tuple, and stores it
   *		in the given slot.	Note that the result will be a "virtual" tuple
   *		unless ExecMaterializeSlot() is then called to force it to be
   *		converted to a physical tuple.	The slot must have a tupledesc
   *		that matches the output of the tlist!
   *
   *		The planner very often produces tlists that consist entirely of
   *		simple Var references (lower levels of a plan tree almost always
   *		look like that).  And top-level tlists are often mostly Vars too.
   *		We therefore optimize execution of simple-Var tlist entries.
   *		The pi_targetlist list actually contains only the tlist entries that
   *		aren't simple Vars, while those that are Vars are processed using the
   *		varSlotOffsets/varNumbers/varOutputCols arrays.
   *
   *		The lastXXXVar fields are used to optimize fetching of fields from
   *		input tuples: they let us do a slot_getsomeattrs() call to ensure
   *		that all needed attributes are extracted in one pass.
   *
   *		targetlist		target list for projection (non-Var expressions only)
   *		exprContext		expression context in which to evaluate targetlist
   *		slot			slot to place projection result in
   *		itemIsDone		workspace array for ExecProject
   *		directMap		true if varOutputCols[] is an identity map
   *		numSimpleVars	number of simple Vars found in original tlist
   *		varSlotOffsets	array indicating which slot each simple Var is from
   *		varNumbers		array containing input attr numbers of simple Vars
   *		varOutputCols	array containing output attr numbers of simple Vars
   *		lastInnerVar	highest attnum from inner tuple slot (0 if none)
   *		lastOuterVar	highest attnum from outer tuple slot (0 if none)
   *		lastScanVar		highest attnum from scan tuple slot (0 if none)
   * ----------------
   */
  typedef struct ProjectionInfo
  {
  	NodeTag		type;
  	List	   *pi_targetlist;
  	ExprContext *pi_exprContext;
  	TupleTableSlot *pi_slot;
  	ExprDoneCond *pi_itemIsDone;
  	bool		pi_directMap;
  	int			pi_numSimpleVars;
  	int		   *pi_varSlotOffsets;
  	int		   *pi_varNumbers;
  	int		   *pi_varOutputCols;
  	int			pi_lastInnerVar;
  	int			pi_lastOuterVar;
  	int			pi_lastScanVar;
  } ProjectionInfo;
  
  /* ----------------
   *	  JunkFilter
   *
   *	  This class is used to store information regarding junk attributes.
   *	  A junk attribute is an attribute in a tuple that is needed only for
   *	  storing intermediate information in the executor, and does not belong
   *	  in emitted tuples.  For example, when we do an UPDATE query,
   *	  the planner adds a "junk" entry to the targetlist so that the tuples
   *	  returned to ExecutePlan() contain an extra attribute: the ctid of
   *	  the tuple to be updated.	This is needed to do the update, but we
   *	  don't want the ctid to be part of the stored new tuple!  So, we
   *	  apply a "junk filter" to remove the junk attributes and form the
   *	  real output tuple.  The junkfilter code also provides routines to
   *	  extract the values of the junk attribute(s) from the input tuple.
   *
   *	  targetList:		the original target list (including junk attributes).
   *	  cleanTupType:		the tuple descriptor for the "clean" tuple (with
   *						junk attributes removed).
   *	  cleanMap:			A map with the correspondence between the non-junk
   *						attribute numbers of the "original" tuple and the
   *						attribute numbers of the "clean" tuple.
   *	  resultSlot:		tuple slot used to hold cleaned tuple.
   *	  junkAttNo:		not used by junkfilter code.  Can be used by caller
   *						to remember the attno of a specific junk attribute
   *						(execMain.c stores the "ctid" attno here).
   * ----------------
   */
  typedef struct JunkFilter
  {
  	NodeTag		type;
  	List	   *jf_targetList;
  	TupleDesc	jf_cleanTupType;
  	AttrNumber *jf_cleanMap;
  	TupleTableSlot *jf_resultSlot;
  	AttrNumber	jf_junkAttNo;
  } JunkFilter;
  
  /* ----------------
   *	  ResultRelInfo information
   *
   *		Whenever we update an existing relation, we have to
   *		update indices on the relation, and perhaps also fire triggers.
   *		The ResultRelInfo class is used to hold all the information needed
   *		about a result relation, including indices.. -cim 10/15/89
   *
   *		RangeTableIndex			result relation's range table index
   *		RelationDesc			relation descriptor for result relation
   *		NumIndices				# of indices existing on result relation
   *		IndexRelationDescs		array of relation descriptors for indices
   *		IndexRelationInfo		array of key/attr info for indices
   *		TrigDesc				triggers to be fired, if any
   *		TrigFunctions			cached lookup info for trigger functions
   *		TrigWhenExprs			array of trigger WHEN expr states
   *		TrigInstrument			optional runtime measurements for triggers
   *		ConstraintExprs			array of constraint-checking expr states
   *		junkFilter				for removing junk attributes from tuples
   *		projectReturning		for computing a RETURNING list
   * ----------------
   */
  typedef struct ResultRelInfo
  {
  	NodeTag		type;
  	Index		ri_RangeTableIndex;
  	Relation	ri_RelationDesc;
  	int			ri_NumIndices;
  	RelationPtr ri_IndexRelationDescs;
  	IndexInfo **ri_IndexRelationInfo;
  	TriggerDesc *ri_TrigDesc;
  	FmgrInfo   *ri_TrigFunctions;
  	List	  **ri_TrigWhenExprs;
  	struct Instrumentation *ri_TrigInstrument;
  	List	  **ri_ConstraintExprs;
  	JunkFilter *ri_junkFilter;
  	ProjectionInfo *ri_projectReturning;
  } ResultRelInfo;
  
  /* ----------------
   *	  EState information
   *
   * Master working state for an Executor invocation
   * ----------------
   */
  typedef struct EState
  {
  	NodeTag		type;
  
  	/* Basic state for all query types: */
  	ScanDirection es_direction; /* current scan direction */
  	Snapshot	es_snapshot;	/* time qual to use */
  	Snapshot	es_crosscheck_snapshot; /* crosscheck time qual for RI */
  	List	   *es_range_table; /* List of RangeTblEntry */
  	PlannedStmt *es_plannedstmt;	/* link to top of plan tree */
  
  	JunkFilter *es_junkFilter;	/* top-level junk filter, if any */
  
  	/* If query can insert/delete tuples, the command ID to mark them with */
  	CommandId	es_output_cid;
  
  	/* Info about target table for insert/update/delete queries: */
  	ResultRelInfo *es_result_relations; /* array of ResultRelInfos */
  	int			es_num_result_relations;		/* length of array */
  	ResultRelInfo *es_result_relation_info;		/* currently active array elt */
  
  	/* Stuff used for firing triggers: */
  	List	   *es_trig_target_relations;		/* trigger-only ResultRelInfos */
  	TupleTableSlot *es_trig_tuple_slot; /* for trigger output tuples */
  	TupleTableSlot *es_trig_oldtup_slot;		/* for trigger old tuples */
  
  	/* Parameter info: */
  	ParamListInfo es_param_list_info;	/* values of external params */
  	ParamExecData *es_param_exec_vals;	/* values of internal params */
  
  	/* Other working state: */
  	MemoryContext es_query_cxt; /* per-query context in which EState lives */
  
  	List	   *es_tupleTable;	/* List of TupleTableSlots */
  
  	List	   *es_rowMarks;	/* List of ExecRowMarks */
  
  	uint32		es_processed;	/* # of tuples processed */
  	Oid			es_lastoid;		/* last oid processed (by INSERT) */
  
  	int			es_instrument;	/* OR of InstrumentOption flags */
  	bool		es_select_into; /* true if doing SELECT INTO */
  	bool		es_into_oids;	/* true to generate OIDs in SELECT INTO */
  
  	List	   *es_exprcontexts;	/* List of ExprContexts within EState */
  
  	List	   *es_subplanstates;		/* List of PlanState for SubPlans */
  
  	/*
  	 * this ExprContext is for per-output-tuple operations, such as constraint
  	 * checks and index-value computations.  It will be reset for each output
  	 * tuple.  Note that it will be created only if needed.
  	 */
  	ExprContext *es_per_tuple_exprcontext;
  
  	/*
  	 * These fields are for re-evaluating plan quals when an updated tuple is
  	 * substituted in READ COMMITTED mode.	es_epqTuple[] contains tuples that
  	 * scan plan nodes should return instead of whatever they'd normally
  	 * return, or NULL if nothing to return; es_epqTupleSet[] is true if a
  	 * particular array entry is valid; and es_epqScanDone[] is state to
  	 * remember if the tuple has been returned already.  Arrays are of size
  	 * list_length(es_range_table) and are indexed by scan node scanrelid - 1.
  	 */
  	HeapTuple  *es_epqTuple;	/* array of EPQ substitute tuples */
  	bool	   *es_epqTupleSet; /* true if EPQ tuple is provided */
  	bool	   *es_epqScanDone; /* true if EPQ tuple has been fetched */
  } EState;
  
  
  /*
   * ExecRowMark -
   *	   runtime representation of FOR UPDATE/SHARE clauses
   *
   * When doing UPDATE, DELETE, or SELECT FOR UPDATE/SHARE, we should have an
   * ExecRowMark for each non-target relation in the query (except inheritance
   * parent RTEs, which can be ignored at runtime).  See PlanRowMark for details
   * about most of the fields.
   *
   * es_rowMarks is a list of these structs.	Each LockRows node has its own
   * list, which is the subset of locks that it is supposed to enforce; note
   * that the per-node lists point to the same structs that are in the global
   * list.
   */
  typedef struct ExecRowMark
  {
  	Relation	relation;		/* opened and suitably locked relation */
  	Index		rti;			/* its range table index */
  	Index		prti;			/* parent range table index, if child */
  	RowMarkType markType;		/* see enum in nodes/plannodes.h */
  	bool		noWait;			/* NOWAIT option */
  	AttrNumber	ctidAttNo;		/* resno of ctid junk attribute, if any */
  	AttrNumber	toidAttNo;		/* resno of tableoid junk attribute, if any */
  	AttrNumber	wholeAttNo;		/* resno of whole-row junk attribute, if any */
  	ItemPointerData curCtid;	/* ctid of currently locked tuple, if any */
  } ExecRowMark;
  
  
  /* ----------------------------------------------------------------
   *				 Tuple Hash Tables
   *
   * All-in-memory tuple hash tables are used for a number of purposes.
   *
   * Note: tab_hash_funcs are for the key datatype(s) stored in the table,
   * and tab_eq_funcs are non-cross-type equality operators for those types.
   * Normally these are the only functions used, but FindTupleHashEntry()
   * supports searching a hashtable using cross-data-type hashing.  For that,
   * the caller must supply hash functions for the LHS datatype as well as
   * the cross-type equality operators to use.  in_hash_funcs and cur_eq_funcs
   * are set to point to the caller's function arrays while doing such a search.
   * During LookupTupleHashEntry(), they point to tab_hash_funcs and
   * tab_eq_funcs respectively.
   * ----------------------------------------------------------------
   */
  typedef struct TupleHashEntryData *TupleHashEntry;
  typedef struct TupleHashTableData *TupleHashTable;
  
  typedef struct TupleHashEntryData
  {
  	/* firstTuple must be the first field in this struct! */
  	MinimalTuple firstTuple;	/* copy of first tuple in this group */
  	/* there may be additional data beyond the end of this struct */
  } TupleHashEntryData;			/* VARIABLE LENGTH STRUCT */
  
  typedef struct TupleHashTableData
  {
  	HTAB	   *hashtab;		/* underlying dynahash table */
  	int			numCols;		/* number of columns in lookup key */
  	AttrNumber *keyColIdx;		/* attr numbers of key columns */
  	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
  	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
  	MemoryContext tablecxt;		/* memory context containing table */
  	MemoryContext tempcxt;		/* context for function evaluations */
  	Size		entrysize;		/* actual size to make each hash entry */
  	TupleTableSlot *tableslot;	/* slot for referencing table entries */
  	/* The following fields are set transiently for each table search: */
  	TupleTableSlot *inputslot;	/* current input tuple's slot */
  	FmgrInfo   *in_hash_funcs;	/* hash functions for input datatype(s) */
  	FmgrInfo   *cur_eq_funcs;	/* equality functions for input vs. table */
  } TupleHashTableData;
  
  typedef HASH_SEQ_STATUS TupleHashIterator;
  
  /*
   * Use InitTupleHashIterator/TermTupleHashIterator for a read/write scan.
   * Use ResetTupleHashIterator if the table can be frozen (in this case no
   * explicit scan termination is needed).
   */
  #define InitTupleHashIterator(htable, iter) \
  	hash_seq_init(iter, (htable)->hashtab)
  #define TermTupleHashIterator(iter) \
  	hash_seq_term(iter)
  #define ResetTupleHashIterator(htable, iter) \
  	do { \
  		hash_freeze((htable)->hashtab); \
  		hash_seq_init(iter, (htable)->hashtab); \
  	} while (0)
  #define ScanTupleHashTable(iter) \
  	((TupleHashEntry) hash_seq_search(iter))
  
  
  /* ----------------------------------------------------------------
   *				 Expression State Trees
   *
   * Each executable expression tree has a parallel ExprState tree.
   *
   * Unlike PlanState, there is not an exact one-for-one correspondence between
   * ExprState node types and Expr node types.  Many Expr node types have no
   * need for node-type-specific run-time state, and so they can use plain
   * ExprState or GenericExprState as their associated ExprState node type.
   * ----------------------------------------------------------------
   */
  
  /* ----------------
   *		ExprState node
   *
   * ExprState is the common superclass for all ExprState-type nodes.
   *
   * It can also be instantiated directly for leaf Expr nodes that need no
   * local run-time state (such as Var, Const, or Param).
   *
   * To save on dispatch overhead, each ExprState node contains a function
   * pointer to the routine to execute to evaluate the node.
   * ----------------
   */
  
  typedef struct ExprState ExprState;
  
  typedef Datum (*ExprStateEvalFunc) (ExprState *expression,
  												ExprContext *econtext,
  												bool *isNull,
  												ExprDoneCond *isDone);
  
  struct ExprState
  {
  	NodeTag		type;
  	Expr	   *expr;			/* associated Expr node */
  	ExprStateEvalFunc evalfunc; /* routine to run to execute node */
  };
  
  /* ----------------
   *		GenericExprState node
   *
   * This is used for Expr node types that need no local run-time state,
   * but have one child Expr node.
   * ----------------
   */
  typedef struct GenericExprState
  {
  	ExprState	xprstate;
  	ExprState  *arg;			/* state of my child node */
  } GenericExprState;
  
  /* ----------------
   *		AggrefExprState node
   * ----------------
   */
  typedef struct AggrefExprState
  {
  	ExprState	xprstate;
  	List	   *args;			/* states of argument expressions */
  	int			aggno;			/* ID number for agg within its plan node */
  } AggrefExprState;
  
  /* ----------------
   *		WindowFuncExprState node
   * ----------------
   */
  typedef struct WindowFuncExprState
  {
  	ExprState	xprstate;
  	List	   *args;			/* states of argument expressions */
  	int			wfuncno;		/* ID number for wfunc within its plan node */
  } WindowFuncExprState;
  
  /* ----------------
   *		ArrayRefExprState node
   *
   * Note: array types can be fixed-length (typlen > 0), but only when the
   * element type is itself fixed-length.  Otherwise they are varlena structures
   * and have typlen = -1.  In any case, an array type is never pass-by-value.
   * ----------------
   */
  typedef struct ArrayRefExprState
  {
  	ExprState	xprstate;
  	List	   *refupperindexpr;	/* states for child nodes */
  	List	   *reflowerindexpr;
  	ExprState  *refexpr;
  	ExprState  *refassgnexpr;
  	int16		refattrlength;	/* typlen of array type */
  	int16		refelemlength;	/* typlen of the array element type */
  	bool		refelembyval;	/* is the element type pass-by-value? */
  	char		refelemalign;	/* typalign of the element type */
  } ArrayRefExprState;
  
  /* ----------------
   *		FuncExprState node
   *
   * Although named for FuncExpr, this is also used for OpExpr, DistinctExpr,
   * and NullIf nodes; be careful to check what xprstate.expr is actually
   * pointing at!
   * ----------------
   */
  typedef struct FuncExprState
  {
  	ExprState	xprstate;
  	List	   *args;			/* states of argument expressions */
  
  	/*
  	 * Function manager's lookup info for the target function.  If func.fn_oid
  	 * is InvalidOid, we haven't initialized it yet (nor any of the following
  	 * fields).
  	 */
  	FmgrInfo	func;
  
  	/*
  	 * For a set-returning function (SRF) that returns a tuplestore, we keep
  	 * the tuplestore here and dole out the result rows one at a time. The
  	 * slot holds the row currently being returned.
  	 */
  	Tuplestorestate *funcResultStore;
  	TupleTableSlot *funcResultSlot;
  
  	/*
  	 * In some cases we need to compute a tuple descriptor for the function's
  	 * output.	If so, it's stored here.
  	 */
  	TupleDesc	funcResultDesc;
  	bool		funcReturnsTuple;		/* valid when funcResultDesc isn't
  										 * NULL */
  
  	/*
  	 * We need to store argument values across calls when evaluating a SRF
  	 * that uses value-per-call mode.
  	 *
  	 * setArgsValid is true when we are evaluating a set-valued function and
  	 * we are in the middle of a call series; we want to pass the same
  	 * argument values to the function again (and again, until it returns
  	 * ExprEndResult).
  	 */
  	bool		setArgsValid;
  
  	/*
  	 * Flag to remember whether we found a set-valued argument to the
  	 * function. This causes the function result to be a set as well. Valid
  	 * only when setArgsValid is true or funcResultStore isn't NULL.
  	 */
  	bool		setHasSetArg;	/* some argument returns a set */
  
  	/*
  	 * Flag to remember whether we have registered a shutdown callback for
  	 * this FuncExprState.	We do so only if funcResultStore or setArgsValid
  	 * has been set at least once (since all the callback is for is to release
  	 * the tuplestore or clear setArgsValid).
  	 */
  	bool		shutdown_reg;	/* a shutdown callback is registered */
  
  	/*
  	 * Current argument data for a set-valued function; contains valid data
  	 * only if setArgsValid is true.
  	 */
  	FunctionCallInfoData setArgs;
  } FuncExprState;
  
  /* ----------------
   *		ScalarArrayOpExprState node
   *
   * This is a FuncExprState plus some additional data.
   * ----------------
   */
  typedef struct ScalarArrayOpExprState
  {
  	FuncExprState fxprstate;
  	/* Cached info about array element type */
  	Oid			element_type;
  	int16		typlen;
  	bool		typbyval;
  	char		typalign;
  } ScalarArrayOpExprState;
  
  /* ----------------
   *		BoolExprState node
   * ----------------
   */
  typedef struct BoolExprState
  {
  	ExprState	xprstate;
  	List	   *args;			/* states of argument expression(s) */
  } BoolExprState;
  
  /* ----------------
   *		SubPlanState node
   * ----------------
   */
  typedef struct SubPlanState
  {
  	ExprState	xprstate;
  	struct PlanState *planstate;	/* subselect plan's state tree */
  	ExprState  *testexpr;		/* state of combining expression */
  	List	   *args;			/* states of argument expression(s) */
  	HeapTuple	curTuple;		/* copy of most recent tuple from subplan */
  	/* these are used when hashing the subselect's output: */
  	ProjectionInfo *projLeft;	/* for projecting lefthand exprs */
  	ProjectionInfo *projRight;	/* for projecting subselect output */
  	TupleHashTable hashtable;	/* hash table for no-nulls subselect rows */
  	TupleHashTable hashnulls;	/* hash table for rows with null(s) */
  	bool		havehashrows;	/* TRUE if hashtable is not empty */
  	bool		havenullrows;	/* TRUE if hashnulls is not empty */
  	MemoryContext hashtablecxt;	/* memory context containing hash tables */
  	MemoryContext hashtempcxt;	/* temp memory context for hash tables */
  	ExprContext *innerecontext; /* econtext for computing inner tuples */
  	AttrNumber *keyColIdx;		/* control data for hash tables */
  	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
  	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
  	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
  	FmgrInfo   *cur_eq_funcs;	/* equality functions for LHS vs. table */
  } SubPlanState;
  
  /* ----------------
   *		AlternativeSubPlanState node
   * ----------------
   */
  typedef struct AlternativeSubPlanState
  {
  	ExprState	xprstate;
  	List	   *subplans;		/* states of alternative subplans */
  	int			active;			/* list index of the one we're using */
  } AlternativeSubPlanState;
  
  /* ----------------
   *		FieldSelectState node
   * ----------------
   */
  typedef struct FieldSelectState
  {
  	ExprState	xprstate;
  	ExprState  *arg;			/* input expression */
  	TupleDesc	argdesc;		/* tupdesc for most recent input */
  } FieldSelectState;
  
  /* ----------------
   *		FieldStoreState node
   * ----------------
   */
  typedef struct FieldStoreState
  {
  	ExprState	xprstate;
  	ExprState  *arg;			/* input tuple value */
  	List	   *newvals;		/* new value(s) for field(s) */
  	TupleDesc	argdesc;		/* tupdesc for most recent input */
  } FieldStoreState;
  
  /* ----------------
   *		CoerceViaIOState node
   * ----------------
   */
  typedef struct CoerceViaIOState
  {
  	ExprState	xprstate;
  	ExprState  *arg;			/* input expression */
  	FmgrInfo	outfunc;		/* lookup info for source output function */
  	FmgrInfo	infunc;			/* lookup info for result input function */
  	Oid			intypioparam;	/* argument needed for input function */
  } CoerceViaIOState;
  
  /* ----------------
   *		ArrayCoerceExprState node
   * ----------------
   */
  typedef struct ArrayCoerceExprState
  {
  	ExprState	xprstate;
  	ExprState  *arg;			/* input array value */
  	Oid			resultelemtype; /* element type of result array */
  	FmgrInfo	elemfunc;		/* lookup info for element coercion function */
  	/* use struct pointer to avoid including array.h here */
  	struct ArrayMapState *amstate;		/* workspace for array_map */
  } ArrayCoerceExprState;
  
  /* ----------------
   *		ConvertRowtypeExprState node
   * ----------------
   */
  typedef struct ConvertRowtypeExprState
  {
  	ExprState	xprstate;
  	ExprState  *arg;			/* input tuple value */
  	TupleDesc	indesc;			/* tupdesc for source rowtype */
  	TupleDesc	outdesc;		/* tupdesc for result rowtype */
  	/* use "struct" so we needn't include tupconvert.h here */
  	struct TupleConversionMap *map;
  	bool		initialized;
  } ConvertRowtypeExprState;
  
  /* ----------------
   *		CaseExprState node
   * ----------------
   */
  typedef struct CaseExprState
  {
  	ExprState	xprstate;
  	ExprState  *arg;			/* implicit equality comparison argument */
  	List	   *args;			/* the arguments (list of WHEN clauses) */
  	ExprState  *defresult;		/* the default result (ELSE clause) */
  } CaseExprState;
  
  /* ----------------
   *		CaseWhenState node
   * ----------------
   */
  typedef struct CaseWhenState
  {
  	ExprState	xprstate;
  	ExprState  *expr;			/* condition expression */
  	ExprState  *result;			/* substitution result */
  } CaseWhenState;
  
  /* ----------------
   *		ArrayExprState node
   *
   * Note: ARRAY[] expressions always produce varlena arrays, never fixed-length
   * arrays.
   * ----------------
   */
  typedef struct ArrayExprState
  {
  	ExprState	xprstate;
  	List	   *elements;		/* states for child nodes */
  	int16		elemlength;		/* typlen of the array element type */
  	bool		elembyval;		/* is the element type pass-by-value? */
  	char		elemalign;		/* typalign of the element type */
  } ArrayExprState;
  
  /* ----------------
   *		RowExprState node
   * ----------------
   */
  typedef struct RowExprState
  {
  	ExprState	xprstate;
  	List	   *args;			/* the arguments */
  	TupleDesc	tupdesc;		/* descriptor for result tuples */
  } RowExprState;
  
  /* ----------------
   *		RowCompareExprState node
   * ----------------
   */
  typedef struct RowCompareExprState
  {
  	ExprState	xprstate;
  	List	   *largs;			/* the left-hand input arguments */
  	List	   *rargs;			/* the right-hand input arguments */
  	FmgrInfo   *funcs;			/* array of comparison function info */
  } RowCompareExprState;
  
  /* ----------------
   *		CoalesceExprState node
   * ----------------
   */
  typedef struct CoalesceExprState
  {
  	ExprState	xprstate;
  	List	   *args;			/* the arguments */
  } CoalesceExprState;
  
  /* ----------------
   *		MinMaxExprState node
   * ----------------
   */
  typedef struct MinMaxExprState
  {
  	ExprState	xprstate;
  	List	   *args;			/* the arguments */
  	FmgrInfo	cfunc;			/* lookup info for comparison func */
  } MinMaxExprState;
  
  /* ----------------
   *		XmlExprState node
   * ----------------
   */
  typedef struct XmlExprState
  {
  	ExprState	xprstate;
  	List	   *named_args;		/* ExprStates for named arguments */
  	List	   *args;			/* ExprStates for other arguments */
  } XmlExprState;
  
  /* ----------------
   *		NullTestState node
   * ----------------
   */
  typedef struct NullTestState
  {
  	ExprState	xprstate;
  	ExprState  *arg;			/* input expression */
  	/* used only if input is of composite type: */
  	TupleDesc	argdesc;		/* tupdesc for most recent input */
  } NullTestState;
  
  /* ----------------
   *		CoerceToDomainState node
   * ----------------
   */
  typedef struct CoerceToDomainState
  {
  	ExprState	xprstate;
  	ExprState  *arg;			/* input expression */
  	/* Cached list of constraints that need to be checked */
  	List	   *constraints;	/* list of DomainConstraintState nodes */
  } CoerceToDomainState;
  
  /*
   * DomainConstraintState - one item to check during CoerceToDomain
   *
   * Note: this is just a Node, and not an ExprState, because it has no
   * corresponding Expr to link to.  Nonetheless it is part of an ExprState
   * tree, so we give it a name following the xxxState convention.
   */
  typedef enum DomainConstraintType
  {
  	DOM_CONSTRAINT_NOTNULL,
  	DOM_CONSTRAINT_CHECK
  } DomainConstraintType;
  
  typedef struct DomainConstraintState
  {
  	NodeTag		type;
  	DomainConstraintType constrainttype;		/* constraint type */
  	char	   *name;			/* name of constraint (for error msgs) */
  	ExprState  *check_expr;		/* for CHECK, a boolean expression */
  } DomainConstraintState;
  
  
  /* ----------------------------------------------------------------
   *				 Executor State Trees
   *
   * An executing query has a PlanState tree paralleling the Plan tree
   * that describes the plan.
   * ----------------------------------------------------------------
   */
  
  /* ----------------
   *		PlanState node
   *
   * We never actually instantiate any PlanState nodes; this is just the common
   * abstract superclass for all PlanState-type nodes.
   * ----------------
   */
  typedef struct PlanState
  {
  	NodeTag		type;
  
  	Plan	   *plan;			/* associated Plan node */
  
  	EState	   *state;			/* at execution time, states of individual
  								 * nodes point to one EState for the whole
  								 * top-level plan */
  
  	struct Instrumentation *instrument; /* Optional runtime stats for this
  										 * plan node */
  
  	/*
  	 * Common structural data for all Plan types.  These links to subsidiary
  	 * state trees parallel links in the associated plan tree (except for the
  	 * subPlan list, which does not exist in the plan tree).
  	 */
  	List	   *targetlist;		/* target list to be computed at this node */
  	List	   *qual;			/* implicitly-ANDed qual conditions */
  	struct PlanState *lefttree; /* input plan tree(s) */
  	struct PlanState *righttree;
  	List	   *initPlan;		/* Init SubPlanState nodes (un-correlated expr
  								 * subselects) */
  	List	   *subPlan;		/* SubPlanState nodes in my expressions */
  
  	/*
  	 * State for management of parameter-change-driven rescanning
  	 */
  	Bitmapset  *chgParam;		/* set of IDs of changed Params */
  
  	/*
  	 * Other run-time state needed by most if not all node types.
  	 */
  	TupleTableSlot *ps_ResultTupleSlot; /* slot for my result tuples */
  	ExprContext *ps_ExprContext;	/* node's expression-evaluation context */
  	ProjectionInfo *ps_ProjInfo;	/* info for doing tuple projection */
  	bool		ps_TupFromTlist;/* state flag for processing set-valued
  								 * functions in targetlist */
  } PlanState;
  
  /* ----------------
   *	these are defined to avoid confusion problems with "left"
   *	and "right" and "inner" and "outer".  The convention is that
   *	the "left" plan is the "outer" plan and the "right" plan is
   *	the inner plan, but these make the code more readable.
   * ----------------
   */
  #define innerPlanState(node)		(((PlanState *)(node))->righttree)
  #define outerPlanState(node)		(((PlanState *)(node))->lefttree)
  
  /*
   * EPQState is state for executing an EvalPlanQual recheck on a candidate
   * tuple in ModifyTable or LockRows.  The estate and planstate fields are
   * NULL if inactive.
   */
  typedef struct EPQState
  {
  	EState	   *estate;			/* subsidiary EState */
  	PlanState  *planstate;		/* plan state tree ready to be executed */
  	TupleTableSlot *origslot;	/* original output tuple to be rechecked */
  	Plan	   *plan;			/* plan tree to be executed */
  	List	   *rowMarks;		/* ExecRowMarks (non-locking only) */
  	int			epqParam;		/* ID of Param to force scan node re-eval */
  } EPQState;
  
  
  /* ----------------
   *	 ResultState information
   * ----------------
   */
  typedef struct ResultState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	ExprState  *resconstantqual;
  	bool		rs_done;		/* are we done? */
  	bool		rs_checkqual;	/* do we need to check the qual? */
  } ResultState;
  
  /* ----------------
   *	 ModifyTableState information
   * ----------------
   */
  typedef struct ModifyTableState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	CmdType		operation;
  	PlanState **mt_plans;		/* subplans (one per target rel) */
  	int			mt_nplans;		/* number of plans in the array */
  	int			mt_whichplan;	/* which one is being executed (0..n-1) */
  	EPQState	mt_epqstate;	/* for evaluating EvalPlanQual rechecks */
  	bool		fireBSTriggers; /* do we need to fire stmt triggers? */
  } ModifyTableState;
  
  /* ----------------
   *	 AppendState information
   *
   *		nplans			how many plans are in the array
   *		whichplan		which plan is being executed (0 .. n-1)
   * ----------------
   */
  typedef struct AppendState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	PlanState **appendplans;	/* array of PlanStates for my inputs */
  	int			as_nplans;
  	int			as_whichplan;
  } AppendState;
  
  /* ----------------
   *	 MergeAppendState information
   *
   *		nplans			how many plans are in the array
   *		nkeys			number of sort key columns
   *		scankeys		sort keys in ScanKey representation
   *		slots			current output tuple of each subplan
   *		heap			heap of active tuples (represented as array indexes)
   *		heap_size		number of active heap entries
   *		initialized		true if we have fetched first tuple from each subplan
   *		last_slot		last subplan fetched from (which must be re-called)
   * ----------------
   */
  typedef struct MergeAppendState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	PlanState **mergeplans;		/* array of PlanStates for my inputs */
  	int			ms_nplans;
  	int			ms_nkeys;
  	ScanKey		ms_scankeys;	/* array of length ms_nkeys */
  	TupleTableSlot **ms_slots;	/* array of length ms_nplans */
  	int			*ms_heap;		/* array of length ms_nplans */
  	int			ms_heap_size;	/* current active length of ms_heap[] */
  	bool		ms_initialized;	/* are subplans started? */
  	int			ms_last_slot;	/* last subplan slot we returned from */
  } MergeAppendState;
  
  /* ----------------
   *	 RecursiveUnionState information
   *
   *		RecursiveUnionState is used for performing a recursive union.
   *
   *		recursing			T when we're done scanning the non-recursive term
   *		intermediate_empty	T if intermediate_table is currently empty
   *		working_table		working table (to be scanned by recursive term)
   *		intermediate_table	current recursive output (next generation of WT)
   * ----------------
   */
  typedef struct RecursiveUnionState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	bool		recursing;
  	bool		intermediate_empty;
  	Tuplestorestate *working_table;
  	Tuplestorestate *intermediate_table;
  	/* Remaining fields are unused in UNION ALL case */
  	FmgrInfo   *eqfunctions;	/* per-grouping-field equality fns */
  	FmgrInfo   *hashfunctions;	/* per-grouping-field hash fns */
  	MemoryContext tempContext;	/* short-term context for comparisons */
  	TupleHashTable hashtable;	/* hash table for tuples already seen */
  	MemoryContext tableContext; /* memory context containing hash table */
  } RecursiveUnionState;
  
  /* ----------------
   *	 BitmapAndState information
   * ----------------
   */
  typedef struct BitmapAndState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	PlanState **bitmapplans;	/* array of PlanStates for my inputs */
  	int			nplans;			/* number of input plans */
  } BitmapAndState;
  
  /* ----------------
   *	 BitmapOrState information
   * ----------------
   */
  typedef struct BitmapOrState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	PlanState **bitmapplans;	/* array of PlanStates for my inputs */
  	int			nplans;			/* number of input plans */
  } BitmapOrState;
  
  /* ----------------------------------------------------------------
   *				 Scan State Information
   * ----------------------------------------------------------------
   */
  
  /* ----------------
   *	 ScanState information
   *
   *		ScanState extends PlanState for node types that represent
   *		scans of an underlying relation.  It can also be used for nodes
   *		that scan the output of an underlying plan node --- in that case,
   *		only ScanTupleSlot is actually useful, and it refers to the tuple
   *		retrieved from the subplan.
   *
   *		currentRelation    relation being scanned (NULL if none)
   *		currentScanDesc    current scan descriptor for scan (NULL if none)
   *		ScanTupleSlot	   pointer to slot in tuple table holding scan tuple
   * ----------------
   */
  typedef struct ScanState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	Relation	ss_currentRelation;
  	HeapScanDesc ss_currentScanDesc;
  	TupleTableSlot *ss_ScanTupleSlot;
  } ScanState;
  
  /*
   * SeqScan uses a bare ScanState as its state node, since it needs
   * no additional fields.
   */
  typedef ScanState SeqScanState;
  
  /*
   * These structs store information about index quals that don't have simple
   * constant right-hand sides.  See comments for ExecIndexBuildScanKeys()
   * for discussion.
   */
  typedef struct
  {
  	ScanKey		scan_key;		/* scankey to put value into */
  	ExprState  *key_expr;		/* expr to evaluate to get value */
  	bool		key_toastable;	/* is expr's result a toastable datatype? */
  } IndexRuntimeKeyInfo;
  
  typedef struct
  {
  	ScanKey		scan_key;		/* scankey to put value into */
  	ExprState  *array_expr;		/* expr to evaluate to get array value */
  	int			next_elem;		/* next array element to use */
  	int			num_elems;		/* number of elems in current array value */
  	Datum	   *elem_values;	/* array of num_elems Datums */
  	bool	   *elem_nulls;		/* array of num_elems is-null flags */
  } IndexArrayKeyInfo;
  
  /* ----------------
   *	 IndexScanState information
   *
   *		indexqualorig	   execution state for indexqualorig expressions
   *		ScanKeys		   Skey structures to scan index rel
   *		NumScanKeys		   number of Skey structs
   *		RuntimeKeys		   info about Skeys that must be evaluated at runtime
   *		NumRuntimeKeys	   number of RuntimeKeys structs
   *		RuntimeKeysReady   true if runtime Skeys have been computed
   *		RuntimeContext	   expr context for evaling runtime Skeys
   *		RelationDesc	   index relation descriptor
   *		ScanDesc		   index scan descriptor
   * ----------------
   */
  typedef struct IndexScanState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	List	   *indexqualorig;
  	ScanKey		iss_ScanKeys;
  	int			iss_NumScanKeys;
  	IndexRuntimeKeyInfo *iss_RuntimeKeys;
  	int			iss_NumRuntimeKeys;
  	bool		iss_RuntimeKeysReady;
  	ExprContext *iss_RuntimeContext;
  	Relation	iss_RelationDesc;
  	IndexScanDesc iss_ScanDesc;
  } IndexScanState;
  
  /* ----------------
   *	 BitmapIndexScanState information
   *
   *		result			   bitmap to return output into, or NULL
   *		ScanKeys		   Skey structures to scan index rel
   *		NumScanKeys		   number of Skey structs
   *		RuntimeKeys		   info about Skeys that must be evaluated at runtime
   *		NumRuntimeKeys	   number of RuntimeKeys structs
   *		ArrayKeys		   info about Skeys that come from ScalarArrayOpExprs
   *		NumArrayKeys	   number of ArrayKeys structs
   *		RuntimeKeysReady   true if runtime Skeys have been computed
   *		RuntimeContext	   expr context for evaling runtime Skeys
   *		RelationDesc	   index relation descriptor
   *		ScanDesc		   index scan descriptor
   * ----------------
   */
  typedef struct BitmapIndexScanState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	TIDBitmap  *biss_result;
  	ScanKey		biss_ScanKeys;
  	int			biss_NumScanKeys;
  	IndexRuntimeKeyInfo *biss_RuntimeKeys;
  	int			biss_NumRuntimeKeys;
  	IndexArrayKeyInfo *biss_ArrayKeys;
  	int			biss_NumArrayKeys;
  	bool		biss_RuntimeKeysReady;
  	ExprContext *biss_RuntimeContext;
  	Relation	biss_RelationDesc;
  	IndexScanDesc biss_ScanDesc;
  } BitmapIndexScanState;
  
  /* ----------------
   *	 BitmapHeapScanState information
   *
   *		bitmapqualorig	   execution state for bitmapqualorig expressions
   *		tbm				   bitmap obtained from child index scan(s)
   *		tbmiterator		   iterator for scanning current pages
   *		tbmres			   current-page data
   *		prefetch_iterator  iterator for prefetching ahead of current page
   *		prefetch_pages	   # pages prefetch iterator is ahead of current
   *		prefetch_target    target prefetch distance
   * ----------------
   */
  typedef struct BitmapHeapScanState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	List	   *bitmapqualorig;
  	TIDBitmap  *tbm;
  	TBMIterator *tbmiterator;
  	TBMIterateResult *tbmres;
  	TBMIterator *prefetch_iterator;
  	int			prefetch_pages;
  	int			prefetch_target;
  } BitmapHeapScanState;
  
  /* ----------------
   *	 TidScanState information
   *
   *		isCurrentOf    scan has a CurrentOfExpr qual
   *		NumTids		   number of tids in this scan
   *		TidPtr		   index of currently fetched tid
   *		TidList		   evaluated item pointers (array of size NumTids)
   * ----------------
   */
  typedef struct TidScanState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	List	   *tss_tidquals;	/* list of ExprState nodes */
  	bool		tss_isCurrentOf;
  	int			tss_NumTids;
  	int			tss_TidPtr;
  	int			tss_MarkTidPtr;
  	ItemPointerData *tss_TidList;
  	HeapTupleData tss_htup;
  } TidScanState;
  
  /* ----------------
   *	 SubqueryScanState information
   *
   *		SubqueryScanState is used for scanning a sub-query in the range table.
   *		ScanTupleSlot references the current output tuple of the sub-query.
   * ----------------
   */
  typedef struct SubqueryScanState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	PlanState  *subplan;
  } SubqueryScanState;
  
  /* ----------------
   *	 FunctionScanState information
   *
   *		Function nodes are used to scan the results of a
   *		function appearing in FROM (typically a function returning set).
   *
   *		eflags				node's capability flags
   *		tupdesc				expected return tuple description
   *		tuplestorestate		private state of tuplestore.c
   *		funcexpr			state for function expression being evaluated
   * ----------------
   */
  typedef struct FunctionScanState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	int			eflags;
  	TupleDesc	tupdesc;
  	Tuplestorestate *tuplestorestate;
  	ExprState  *funcexpr;
  } FunctionScanState;
  
  /* ----------------
   *	 ValuesScanState information
   *
   *		ValuesScan nodes are used to scan the results of a VALUES list
   *
   *		rowcontext			per-expression-list context
   *		exprlists			array of expression lists being evaluated
   *		array_len			size of array
   *		curr_idx			current array index (0-based)
   *		marked_idx			marked position (for mark/restore)
   *
   *	Note: ss.ps.ps_ExprContext is used to evaluate any qual or projection
   *	expressions attached to the node.  We create a second ExprContext,
   *	rowcontext, in which to build the executor expression state for each
   *	Values sublist.  Resetting this context lets us get rid of expression
   *	state for each row, avoiding major memory leakage over a long values list.
   * ----------------
   */
  typedef struct ValuesScanState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	ExprContext *rowcontext;
  	List	  **exprlists;
  	int			array_len;
  	int			curr_idx;
  	int			marked_idx;
  } ValuesScanState;
  
  /* ----------------
   *	 CteScanState information
   *
   *		CteScan nodes are used to scan a CommonTableExpr query.
   *
   * Multiple CteScan nodes can read out from the same CTE query.  We use
   * a tuplestore to hold rows that have been read from the CTE query but
   * not yet consumed by all readers.
   * ----------------
   */
  typedef struct CteScanState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	int			eflags;			/* capability flags to pass to tuplestore */
  	int			readptr;		/* index of my tuplestore read pointer */
  	PlanState  *cteplanstate;	/* PlanState for the CTE query itself */
  	/* Link to the "leader" CteScanState (possibly this same node) */
  	struct CteScanState *leader;
  	/* The remaining fields are only valid in the "leader" CteScanState */
  	Tuplestorestate *cte_table; /* rows already read from the CTE query */
  	bool		eof_cte;		/* reached end of CTE query? */
  } CteScanState;
  
  /* ----------------
   *	 WorkTableScanState information
   *
   *		WorkTableScan nodes are used to scan the work table created by
   *		a RecursiveUnion node.	We locate the RecursiveUnion node
   *		during executor startup.
   * ----------------
   */
  typedef struct WorkTableScanState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	RecursiveUnionState *rustate;
  } WorkTableScanState;
  
  /* ----------------------------------------------------------------
   *				 Join State Information
   * ----------------------------------------------------------------
   */
  
  /* ----------------
   *	 JoinState information
   *
   *		Superclass for state nodes of join plans.
   * ----------------
   */
  typedef struct JoinState
  {
  	PlanState	ps;
  	JoinType	jointype;
  	List	   *joinqual;		/* JOIN quals (in addition to ps.qual) */
  } JoinState;
  
  /* ----------------
   *	 NestLoopState information
   *
   *		NeedNewOuter	   true if need new outer tuple on next call
   *		MatchedOuter	   true if found a join match for current outer tuple
   *		NullInnerTupleSlot prepared null tuple for left outer joins
   * ----------------
   */
  typedef struct NestLoopState
  {
  	JoinState	js;				/* its first field is NodeTag */
  	bool		nl_NeedNewOuter;
  	bool		nl_MatchedOuter;
  	TupleTableSlot *nl_NullInnerTupleSlot;
  } NestLoopState;
  
  /* ----------------
   *	 MergeJoinState information
   *
   *		NumClauses		   number of mergejoinable join clauses
   *		Clauses			   info for each mergejoinable clause
   *		JoinState		   current "state" of join.  see execdefs.h
   *		ExtraMarks		   true to issue extra Mark operations on inner scan
   *		ConstFalseJoin	   true if we have a constant-false joinqual
   *		FillOuter		   true if should emit unjoined outer tuples anyway
   *		FillInner		   true if should emit unjoined inner tuples anyway
   *		MatchedOuter	   true if found a join match for current outer tuple
   *		MatchedInner	   true if found a join match for current inner tuple
   *		OuterTupleSlot	   slot in tuple table for cur outer tuple
   *		InnerTupleSlot	   slot in tuple table for cur inner tuple
   *		MarkedTupleSlot    slot in tuple table for marked tuple
   *		NullOuterTupleSlot prepared null tuple for right outer joins
   *		NullInnerTupleSlot prepared null tuple for left outer joins
   *		OuterEContext	   workspace for computing outer tuple's join values
   *		InnerEContext	   workspace for computing inner tuple's join values
   * ----------------
   */
  /* private in nodeMergejoin.c: */
  typedef struct MergeJoinClauseData *MergeJoinClause;
  
  typedef struct MergeJoinState
  {
  	JoinState	js;				/* its first field is NodeTag */
  	int			mj_NumClauses;
  	MergeJoinClause mj_Clauses; /* array of length mj_NumClauses */
  	int			mj_JoinState;
  	bool		mj_ExtraMarks;
  	bool		mj_ConstFalseJoin;
  	bool		mj_FillOuter;
  	bool		mj_FillInner;
  	bool		mj_MatchedOuter;
  	bool		mj_MatchedInner;
  	TupleTableSlot *mj_OuterTupleSlot;
  	TupleTableSlot *mj_InnerTupleSlot;
  	TupleTableSlot *mj_MarkedTupleSlot;
  	TupleTableSlot *mj_NullOuterTupleSlot;
  	TupleTableSlot *mj_NullInnerTupleSlot;
  	ExprContext *mj_OuterEContext;
  	ExprContext *mj_InnerEContext;
  } MergeJoinState;
  
  /* ----------------
   *	 HashJoinState information
   *
   *		hj_HashTable			hash table for the hashjoin
   *								(NULL if table not built yet)
   *		hj_CurHashValue			hash value for current outer tuple
   *		hj_CurBucketNo			regular bucket# for current outer tuple
   *		hj_CurSkewBucketNo		skew bucket# for current outer tuple
   *		hj_CurTuple				last inner tuple matched to current outer
   *								tuple, or NULL if starting search
   *								(hj_CurXXX variables are undefined if
   *								OuterTupleSlot is empty!)
   *		hj_OuterHashKeys		the outer hash keys in the hashjoin condition
   *		hj_InnerHashKeys		the inner hash keys in the hashjoin condition
   *		hj_HashOperators		the join operators in the hashjoin condition
   *		hj_OuterTupleSlot		tuple slot for outer tuples
   *		hj_HashTupleSlot		tuple slot for hashed tuples
   *		hj_NullInnerTupleSlot	prepared null tuple for left outer joins
   *		hj_FirstOuterTupleSlot	first tuple retrieved from outer plan
   *		hj_NeedNewOuter			true if need new outer tuple on next call
   *		hj_MatchedOuter			true if found a join match for current outer
   *		hj_OuterNotEmpty		true if outer relation known not empty
   * ----------------
   */
  
  /* these structs are defined in executor/hashjoin.h: */
  typedef struct HashJoinTupleData *HashJoinTuple;
  typedef struct HashJoinTableData *HashJoinTable;
  
  typedef struct HashJoinState
  {
  	JoinState	js;				/* its first field is NodeTag */
  	List	   *hashclauses;	/* list of ExprState nodes */
  	HashJoinTable hj_HashTable;
  	uint32		hj_CurHashValue;
  	int			hj_CurBucketNo;
  	int			hj_CurSkewBucketNo;
  	HashJoinTuple hj_CurTuple;
  	List	   *hj_OuterHashKeys;		/* list of ExprState nodes */
  	List	   *hj_InnerHashKeys;		/* list of ExprState nodes */
  	List	   *hj_HashOperators;		/* list of operator OIDs */
  	TupleTableSlot *hj_OuterTupleSlot;
  	TupleTableSlot *hj_HashTupleSlot;
  	TupleTableSlot *hj_NullInnerTupleSlot;
  	TupleTableSlot *hj_FirstOuterTupleSlot;
  	bool		hj_NeedNewOuter;
  	bool		hj_MatchedOuter;
  	bool		hj_OuterNotEmpty;
  } HashJoinState;
  
  
  /* ----------------------------------------------------------------
   *				 Materialization State Information
   * ----------------------------------------------------------------
   */
  
  /* ----------------
   *	 MaterialState information
   *
   *		materialize nodes are used to materialize the results
   *		of a subplan into a temporary file.
   *
   *		ss.ss_ScanTupleSlot refers to output of underlying plan.
   * ----------------
   */
  typedef struct MaterialState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	int			eflags;			/* capability flags to pass to tuplestore */
  	bool		eof_underlying; /* reached end of underlying plan? */
  	Tuplestorestate *tuplestorestate;
  } MaterialState;
  
  /* ----------------
   *	 SortState information
   * ----------------
   */
  typedef struct SortState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	bool		randomAccess;	/* need random access to sort output? */
  	bool		bounded;		/* is the result set bounded? */
  	int64		bound;			/* if bounded, how many tuples are needed */
  	bool		sort_Done;		/* sort completed yet? */
  	bool		bounded_Done;	/* value of bounded we did the sort with */
  	int64		bound_Done;		/* value of bound we did the sort with */
  	void	   *tuplesortstate; /* private state of tuplesort.c */
  } SortState;
  
  /* ---------------------
   *	GroupState information
   * -------------------------
   */
  typedef struct GroupState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	FmgrInfo   *eqfunctions;	/* per-field lookup data for equality fns */
  	bool		grp_done;		/* indicates completion of Group scan */
  } GroupState;
  
  /* ---------------------
   *	AggState information
   *
   *	ss.ss_ScanTupleSlot refers to output of underlying plan.
   *
   *	Note: ss.ps.ps_ExprContext contains ecxt_aggvalues and
   *	ecxt_aggnulls arrays, which hold the computed agg values for the current
   *	input group during evaluation of an Agg node's output tuple(s).  We
   *	create a second ExprContext, tmpcontext, in which to evaluate input
   *	expressions and run the aggregate transition functions.
   * -------------------------
   */
  /* these structs are private in nodeAgg.c: */
  typedef struct AggStatePerAggData *AggStatePerAgg;
  typedef struct AggStatePerGroupData *AggStatePerGroup;
  
  typedef struct AggState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  	List	   *aggs;			/* all Aggref nodes in targetlist & quals */
  	int			numaggs;		/* length of list (could be zero!) */
  	FmgrInfo   *eqfunctions;	/* per-grouping-field equality fns */
  	FmgrInfo   *hashfunctions;	/* per-grouping-field hash fns */
  	AggStatePerAgg peragg;		/* per-Aggref information */
  	MemoryContext aggcontext;	/* memory context for long-lived data */
  	ExprContext *tmpcontext;	/* econtext for input expressions */
  	bool		agg_done;		/* indicates completion of Agg scan */
  	/* these fields are used in AGG_PLAIN and AGG_SORTED modes: */
  	AggStatePerGroup pergroup;	/* per-Aggref-per-group working state */
  	HeapTuple	grp_firstTuple; /* copy of first tuple of current group */
  	/* these fields are used in AGG_HASHED mode: */
  	TupleHashTable hashtable;	/* hash table with one entry per group */
  	TupleTableSlot *hashslot;	/* slot for loading hash table */
  	List	   *hash_needed;	/* list of columns needed in hash table */
  	bool		table_filled;	/* hash table filled yet? */
  	TupleHashIterator hashiter; /* for iterating through hash table */
  } AggState;
  
  /* ----------------
   *	WindowAggState information
   * ----------------
   */
  /* these structs are private in nodeWindowAgg.c: */
  typedef struct WindowStatePerFuncData *WindowStatePerFunc;
  typedef struct WindowStatePerAggData *WindowStatePerAgg;
  
  typedef struct WindowAggState
  {
  	ScanState	ss;				/* its first field is NodeTag */
  
  	/* these fields are filled in by ExecInitExpr: */
  	List	   *funcs;			/* all WindowFunc nodes in targetlist */
  	int			numfuncs;		/* total number of window functions */
  	int			numaggs;		/* number that are plain aggregates */
  
  	WindowStatePerFunc perfunc; /* per-window-function information */
  	WindowStatePerAgg peragg;	/* per-plain-aggregate information */
  	FmgrInfo   *partEqfunctions;	/* equality funcs for partition columns */
  	FmgrInfo   *ordEqfunctions; /* equality funcs for ordering columns */
  	Tuplestorestate *buffer;	/* stores rows of current partition */
  	int			current_ptr;	/* read pointer # for current */
  	int64		spooled_rows;	/* total # of rows in buffer */
  	int64		currentpos;		/* position of current row in partition */
  	int64		frameheadpos;	/* current frame head position */
  	int64		frametailpos;	/* current frame tail position */
  	/* use struct pointer to avoid including windowapi.h here */
  	struct WindowObjectData *agg_winobj;		/* winobj for aggregate
  												 * fetches */
  	int64		aggregatedbase; /* start row for current aggregates */
  	int64		aggregatedupto; /* rows before this one are aggregated */
  
  	int			frameOptions;	/* frame_clause options, see WindowDef */
  	ExprState  *startOffset;	/* expression for starting bound offset */
  	ExprState  *endOffset;		/* expression for ending bound offset */
  	Datum		startOffsetValue;		/* result of startOffset evaluation */
  	Datum		endOffsetValue; /* result of endOffset evaluation */
  
  	MemoryContext partcontext;	/* context for partition-lifespan data */
  	MemoryContext aggcontext;	/* context for each aggregate data */
  	ExprContext *tmpcontext;	/* short-term evaluation context */
  
  	bool		all_first;		/* true if the scan is starting */
  	bool		all_done;		/* true if the scan is finished */
  	bool		partition_spooled;		/* true if all tuples in current
  										 * partition have been spooled into
  										 * tuplestore */
  	bool		more_partitions;/* true if there's more partitions after this
  								 * one */
  	bool		framehead_valid;/* true if frameheadpos is known up to date
  								 * for current row */
  	bool		frametail_valid;/* true if frametailpos is known up to date
  								 * for current row */
  
  	TupleTableSlot *first_part_slot;	/* first tuple of current or next
  										 * partition */
  
  	/* temporary slots for tuples fetched back from tuplestore */
  	TupleTableSlot *agg_row_slot;
  	TupleTableSlot *temp_slot_1;
  	TupleTableSlot *temp_slot_2;
  } WindowAggState;
  
  /* ----------------
   *	 UniqueState information
   *
   *		Unique nodes are used "on top of" sort nodes to discard
   *		duplicate tuples returned from the sort phase.	Basically
   *		all it does is compare the current tuple from the subplan
   *		with the previously fetched tuple (stored in its result slot).
   *		If the two are identical in all interesting fields, then
   *		we just fetch another tuple from the sort and try again.
   * ----------------
   */
  typedef struct UniqueState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	FmgrInfo   *eqfunctions;	/* per-field lookup data for equality fns */
  	MemoryContext tempContext;	/* short-term context for comparisons */
  } UniqueState;
  
  /* ----------------
   *	 HashState information
   * ----------------
   */
  typedef struct HashState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	HashJoinTable hashtable;	/* hash table for the hashjoin */
  	List	   *hashkeys;		/* list of ExprState nodes */
  	/* hashkeys is same as parent's hj_InnerHashKeys */
  } HashState;
  
  /* ----------------
   *	 SetOpState information
   *
   *		Even in "sorted" mode, SetOp nodes are more complex than a simple
   *		Unique, since we have to count how many duplicates to return.  But
   *		we also support hashing, so this is really more like a cut-down
   *		form of Agg.
   * ----------------
   */
  /* this struct is private in nodeSetOp.c: */
  typedef struct SetOpStatePerGroupData *SetOpStatePerGroup;
  
  typedef struct SetOpState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	FmgrInfo   *eqfunctions;	/* per-grouping-field equality fns */
  	FmgrInfo   *hashfunctions;	/* per-grouping-field hash fns */
  	bool		setop_done;		/* indicates completion of output scan */
  	long		numOutput;		/* number of dups left to output */
  	MemoryContext tempContext;	/* short-term context for comparisons */
  	/* these fields are used in SETOP_SORTED mode: */
  	SetOpStatePerGroup pergroup;	/* per-group working state */
  	HeapTuple	grp_firstTuple; /* copy of first tuple of current group */
  	/* these fields are used in SETOP_HASHED mode: */
  	TupleHashTable hashtable;	/* hash table with one entry per group */
  	MemoryContext tableContext; /* memory context containing hash table */
  	bool		table_filled;	/* hash table filled yet? */
  	TupleHashIterator hashiter; /* for iterating through hash table */
  } SetOpState;
  
  /* ----------------
   *	 LockRowsState information
   *
   *		LockRows nodes are used to enforce FOR UPDATE/FOR SHARE locking.
   * ----------------
   */
  typedef struct LockRowsState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	List	   *lr_rowMarks;	/* List of ExecRowMarks */
  	EPQState	lr_epqstate;	/* for evaluating EvalPlanQual rechecks */
  } LockRowsState;
  
  /* ----------------
   *	 LimitState information
   *
   *		Limit nodes are used to enforce LIMIT/OFFSET clauses.
   *		They just select the desired subrange of their subplan's output.
   *
   * offset is the number of initial tuples to skip (0 does nothing).
   * count is the number of tuples to return after skipping the offset tuples.
   * If no limit count was specified, count is undefined and noCount is true.
   * When lstate == LIMIT_INITIAL, offset/count/noCount haven't been set yet.
   * ----------------
   */
  typedef enum
  {
  	LIMIT_INITIAL,				/* initial state for LIMIT node */
  	LIMIT_RESCAN,				/* rescan after recomputing parameters */
  	LIMIT_EMPTY,				/* there are no returnable rows */
  	LIMIT_INWINDOW,				/* have returned a row in the window */
  	LIMIT_SUBPLANEOF,			/* at EOF of subplan (within window) */
  	LIMIT_WINDOWEND,			/* stepped off end of window */
  	LIMIT_WINDOWSTART			/* stepped off beginning of window */
  } LimitStateCond;
  
  typedef struct LimitState
  {
  	PlanState	ps;				/* its first field is NodeTag */
  	ExprState  *limitOffset;	/* OFFSET parameter, or NULL if none */
  	ExprState  *limitCount;		/* COUNT parameter, or NULL if none */
  	int64		offset;			/* current OFFSET value */
  	int64		count;			/* current COUNT, if any */
  	bool		noCount;		/* if true, ignore count */
  	LimitStateCond lstate;		/* state machine status, as above */
  	int64		position;		/* 1-based index of last tuple returned */
  	TupleTableSlot *subSlot;	/* tuple last obtained from subplan */
  } LimitState;
  
  #endif   /* EXECNODES_H */
  