title: performance issue MySQL 5.7
body: <p>I've migrated my MySQL Database from 5.6 to version 5.7. Now I got a performance issue.</p>
  
  <p>Specific statement are executed in both versions and I noticed that 5.7 is significant slower. Especially with large amount of Data. </p>
  
  <p>Even a simple select statement is much slower</p>
  
  <pre><code>5.6: 2,948 sec
  5.7: 6,536 sec
  </code></pre>
  
  <p>In my application i've got more complex statements that take way more time to execute so it get's unusable.</p>
  
  <p>I've also noticed that the field count of my table matters in 5.7 but not in 5.6.</p>
  
  <p>The configuration values in the my.ini didn't change.</p>
  
  <p>To test this issue you can use the following code:</p>
  
  <pre><code>#Create Tables
  DROP TABLE IF EXISTS aTest;
  DROP TABLE IF EXISTS sTest;
  CREATE TABLE `aTest` (
      `T_BETREFF` CHAR(40) NOT NULL DEFAULT '',
      `T_DATUM` DATETIME NOT NULL DEFAULT '0000-00-00 00:00:00',
      `T_ZEIT` CHAR(5) NOT NULL DEFAULT '',
      `T_SACHBEARB` CHAR(2) NOT NULL DEFAULT '',
      `SYS_UID` INT NOT NULL AUTO_INCREMENT,
      `SYS_DATE` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
      UNIQUE INDEX `TODO01` (`SYS_UID`),
      INDEX `TODO02` (`T_SACHBEARB`)
  )
  COLLATE='latin1_swedish_ci'
  ENGINE=MyISAM;
  
  CREATE TABLE `sTest` (
      `V_NR` CHAR(2) NOT NULL DEFAULT '',
      `V_NAME` CHAR(30) NOT NULL DEFAULT '',
      `SYS_UID` INT NOT NULL AUTO_INCREMENT,
      `SYS_DATE` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
      UNIQUE INDEX `S_VERK01` (`SYS_UID`),
      UNIQUE INDEX `S_VERK02` (`V_NR`)
  )
  COLLATE='latin1_swedish_ci'
  ENGINE=MyISAM;
  
  #Fill Tables
  DROP PROCEDURE IF EXISTS load_foo_atest_data;
  DELIMITER //
  CREATE PROCEDURE load_foo_atest_data()
  BEGIN
      DECLARE v_max int unsigned default 1000000;
      DECLARE v_counter INT UNSIGNED DEFAULT 0;
  
      WHILE v_counter &lt; v_max DO
          INSERT INTO aTest (T_BETREFF, T_DATUM, T_ZEIT, T_SACHBEARB) VALUES('TEST 1234,', NOW(), '00:00', v_counter DIV 100000 * 10);
          IF (v_counter MOD 100000 = 0) THEN
              INSERT INTO sTest (V_NR, V_NAME) VALUES(v_counter DIV 100000 * 10, CONCAT('TEST', v_counter));
          END IF;
          SET v_counter=v_counter+1;
      END WHILE;
  END //
  DELIMITER ;
  
  call load_foo_atest_data();
  </code></pre>
  
  <p>Here my statement:</p>
  
  <pre><code>FLUSH TABLES;
  SELECT * FROM atest
  LEFT JOIN sTEST ON v_nr = t_sachbearb
  GROUP BY atest.sys_uid
  ORDER BY t_datum DESC, t_zeit DESC
  </code></pre>
  
  <p><strong><em>EDIT</em></strong></p>
  
  <p>EXPLAIN results:</p>
  
  <p>5.6:</p>
  
  <pre>
  +----+-------------+-------+--------+---------------+----------+---------+-------------------------------------------+---------+---------------------------------+
  | id | select_type | table |  type  | possible_keys |   key    | key_len |                    ref                    |  rows   |              Extra              |
  +----+-------------+-------+--------+---------------+----------+---------+-------------------------------------------+---------+---------------------------------+
  |  1 | SIMPLE      | atest | ALL    | TODO01        | NULL     | NULL    | NULL                                      | 1000000 | Using temporary; Using filesort |
  |  1 | SIMPLE      | sTEST | eq_ref | S_VERK02      | S_VERK02 | 2       | obs_mysql_bergau_57test.atest.T_SACHBEARB |       1 | NULL                            |
  +----+-------------+-------+--------+---------------+----------+---------+-------------------------------------------+---------+---------------------------------+
  </pre>
  
  <p>5.7</p>
  
  <pre>
  +----+-------------+-------+------------+--------+---------------+----------+---------+-------------------------------------------+---------+----------+---------------------------------+
  | id | select_type | table | partitions |  type  | possible_keys |   key    | key_len |                    ref                    |  rows   | filtered |              Extra              |
  +----+-------------+-------+------------+--------+---------------+----------+---------+-------------------------------------------+---------+----------+---------------------------------+
  |  1 | SIMPLE      | atest | NULL       | ALL    | TODO01        | NULL     | NULL    | NULL                                      | 1000000 | 100.00   | Using temporary; Using filesort |
  |  1 | SIMPLE      | sTEST | NULL       | eq_ref | S_VERK02      | S_VERK02 | 2       | obs_mysql_bergau_57test.atest.T_SACHBEARB |       1 | 100.00   | NULL                            |
  +----+-------------+-------+------------+--------+---------------+----------+---------+-------------------------------------------+---------+----------+---------------------------------+
  </pre>
  
  <p>My.ini:</p>
  
  <pre><code># Other default tuning values
  # MySQL Server Instance Configuration File
  # ----------------------------------------------------------------------
  # Generated by the MySQL Server Instance Configuration Wizard
  #
  #
  # Installation Instructions
  # ----------------------------------------------------------------------
  #
  # On Linux you can copy this file to /etc/my.cnf to set global options,
  # mysql-data-dir/my.cnf to set server-specific options
  # (@localstatedir@ for this installation) or to
  # ~/.my.cnf to set user-specific options.
  #
  # On Windows you should keep this file in the installation directory 
  # of your server (e.g. C:\Program Files\MySQL\MySQL Server X.Y). To
  # make sure the server reads the config file use the startup option 
  # "--defaults-file". 
  #
  # To run run the server from the command line, execute this in a 
  # command line shell, e.g.
  # mysqld --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini"
  #
  # To install the server as a Windows service manually, execute this in a 
  # command line shell, e.g.
  # mysqld --install MySQLXY --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini"
  #
  # And then execute this in a command line shell to start the server, e.g.
  # net start MySQLXY
  #
  #
  # Guildlines for editing this file
  # ----------------------------------------------------------------------
  #
  # In this file, you can use all long options that the program supports.
  # If you want to know the options a program supports, start the program
  # with the "--help" option.
  #
  # More detailed information about the individual options can also be
  # found in the manual.
  #
  # For advice on how to change settings please see
  # http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html
  #
  #
  # CLIENT SECTION
  # ----------------------------------------------------------------------
  #
  # The following options will be read by MySQL client applications.
  # Note that only client applications shipped by MySQL are guaranteed
  # to read this section. If you want your own MySQL client program to
  # honor these values, you need to specify it as an option during the
  # MySQL client library initialization.
  # [client] no-beep
  
  # pipe
  # socket=0.0 port=3306
  
  [mysql]
  
  default-character-set=utf8
  
  
  # SERVER SECTION
  # ----------------------------------------------------------------------
  #
  # The following options will be read by the MySQL Server. Make sure that
  # you have installed the server correctly (see above) so it reads this 
  # file.
  #
  # server_type=1 [mysqld]
  
  # The next three options are mutually exclusive to SERVER_PORT below.
  # skip-networking
  
  # enable-named-pipe
  
  # shared-memory
  
  # shared-memory-base-name=MYSQL
  
  # The Pipe the MySQL Server will use
  # socket=MYSQL
  
  # The TCP/IP Port the MySQL Server will listen on port=3306
  
  # Path to installation directory. All paths are usually resolved relative to this.
  # basedir="C:/Program Files/MySQL/MySQL Server 5.7/"
  
  # Path to the database root datadir=C:/ProgramData/MySQL/MySQL Server 5.7\Data
  
  # The default character set that will be used when a new schema or table is
  # created and no character set is defined character-set-server = latin1
  
  # The default storage engine that will be used when create new tables when default-storage-engine = MYISAM
  
  # Set the SQL mode to strict sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"
  
  # Enable Windows Authentication
  # plugin-load=authentication_windows.dll
  
  # General and Slow logging. log-output=FILE general-log=1 general_log_file="PC-THIEL.log" slow-query-log=1 slow_query_log_file="PC-THIEL-slow.log" long_query_time=10
  
  # Binary Logging.
  # log-bin
  
  # Error Logging. log-error="PC-THIEL.err"
  
  # Server Id. server-id=1
  
  # Secure File Priv. secure-file-priv="C:/ProgramData/MySQL/MySQL Server 5.7/Uploads"
  
  # The maximum amount of concurrent sessions the MySQL server will
  # allow. One of these connections will be reserved for a user with
  # SUPER privileges to allow the administrator to login even if the
  # connection limit has been reached. max_connections=1000
  
  # Query cache is used to cache SELECT results and later return them
  # without actual executing the same query once again. Having the query
  # cache enabled may result in significant speed improvements, if your
  # have a lot of identical queries and rarely changing tables. See the
  # "Qcache_lowmem_prunes" status variable to check if the current value
  # is high enough for your load.
  # Note: In case your tables change very often or if your queries are
  # textually different every time, the query cache may result in a
  # slowdown instead of a performance improvement. query_cache_size = 2G
  
  # The number of open tables for all threads. Increasing this value
  # increases the number of file descriptors that mysqld requires.
  # Therefore you have to make sure to set the amount of open files
  # allowed to at least 4096 in the variable "open-files-limit" in
  # section [mysqld_safe] table_open_cache=2000
  
  # Maximum size for internal (in-memory) temporary tables. If a table
  # grows larger than this value, it is automatically converted to disk
  # based table This limitation is for a single table. There can be many
  # of them. tmp_table_size=3G
  
  # How many threads we should keep in a cache for reuse. When a client
  # disconnects, the client's threads are put in the cache if there aren't
  # more than thread_cache_size threads from before.  This greatly reduces
  # the amount of thread creations needed if you have a lot of new
  # connections. (Normally this doesn't give a notable performance
  # improvement if you have a good thread implementation.) thread_cache_size=10
  
  #*** MyISAM Specific options
  # The maximum size of the temporary file MySQL is allowed to use while
  # recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE.
  # If the file-size would be bigger than this, the index will be created
  # through the key cache (which is slower). myisam_max_sort_file_size=100G
  
  # If the temporary file used for fast index creation would be bigger
  # than using the key cache by the amount specified here, then prefer the
  # key cache method.  This is mainly used to force long character keys in
  # large tables to use the slower key cache method to create the index. myisam_sort_buffer_size=6G
  
  # Size of the Key Buffer, used to cache index blocks for MyISAM tables.
  # Do not set it larger than 30% of your available memory, as some memory
  # is also required by the OS to cache rows. Even if you're not using
  # MyISAM tables, you should still set it to 8-64M as it will also be
  # used for internal temporary disk tables. key_buffer_size = 8G
  
  # Size of the buffer used for doing full table scans of MyISAM tables.
  # Allocated per thread, if a full scan is needed. read_buffer_size=64K read_rnd_buffer_size=256K
  
  #*** INNODB Specific options ***
  # innodb_data_home_dir=0.0
  
  # Use this option if you have a MySQL server with InnoDB support enabled
  # but you do not plan to use it. This will save memory and disk space
  # and speed up some things.
  # skip-innodb
  
  # If set to 1, InnoDB will flush (fsync) the transaction logs to the
  # disk at each commit, which offers full ACID behavior. If you are
  # willing to compromise this safety, and you are running small
  # transactions, you may set this to 0 or 2 to reduce disk I/O to the
  # logs. Value 0 means that the log is only written to the log file and
  # the log file flushed to disk approximately once per second. Value 2
  # means the log is written to the log file at each commit, but the log
  # file is only flushed to disk approximately once per second. innodb_flush_log_at_trx_commit=1
  
  # The size of the buffer InnoDB uses for buffering log data. As soon as
  # it is full, InnoDB will have to flush it to disk. As it is flushed
  # once per second anyway, it does not make sense to have it very large
  # (even with long transactions). innodb_log_buffer_size=1M
  
  # InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and
  # row data. The bigger you set this the less disk I/O is needed to
  # access data in tables. On a dedicated database server you may set this
  # parameter up to 80% of the machine physical memory size. Do not set it
  # too large, though, because competition of the physical memory may
  # cause paging in the operating system.  Note that on 32bit systems you
  # might be limited to 2-3.5G of user level memory per process, so do not
  # set it too high. innodb_buffer_pool_size=8M
  
  # Size of each log file in a log group. You should set the combined size
  # of log files to about 25%-100% of your buffer pool size to avoid
  # unneeded buffer pool flush activity on log file overwrite. However,
  # note that a larger logfile size will increase the time needed for the
  # recovery process. innodb_log_file_size=48M
  
  # Number of threads allowed inside the InnoDB kernel. The optimal value
  # depends highly on the application, hardware as well as the OS
  # scheduler properties. A too high value may lead to thread thrashing. innodb_thread_concurrency=17
  
  # The increment size (in MB) for extending the size of an auto-extend InnoDB system tablespace file when it becomes full. innodb_autoextend_increment=64
  
  # The number of regions that the InnoDB buffer pool is divided into.
  # For systems with buffer pools in the multi-gigabyte range, dividing the buffer pool into separate instances can improve concurrency,
  # by reducing contention as different threads read and write to cached pages. innodb_buffer_pool_instances=8
  
  # Determines the number of threads that can enter InnoDB concurrently. innodb_concurrency_tickets=5000
  
  # Specifies how long in milliseconds (ms) a block inserted into the old sublist must stay there after its first access before
  # it can be moved to the new sublist. innodb_old_blocks_time=1000
  
  # It specifies the maximum number of .ibd files that MySQL can keep open at one time. The minimum value is 10. innodb_open_files=300
  
  # When this variable is enabled, InnoDB updates statistics during metadata statements. innodb_stats_on_metadata=0
  
  # When innodb_file_per_table is enabled (the default in 5.6.6 and higher), InnoDB stores the data and indexes for each newly created table
  # in a separate .ibd file, rather than in the system tablespace. innodb_file_per_table=1
  
  # Use the following list of values: 0 for crc32, 1 for strict_crc32, 2 for innodb, 3 for strict_innodb, 4 for none, 5 for strict_none. innodb_checksum_algorithm=0
  
  # The number of outstanding connection requests MySQL can have.
  # This option is useful when the main MySQL thread gets many connection requests in a very short time.
  # It then takes some time (although very little) for the main thread to check the connection and start a new thread.
  # The back_log value indicates how many requests can be stacked during this short time before MySQL momentarily
  # stops answering new requests.
  # You need to increase this only if you expect a large number of connections in a short period of time. back_log=80
  
  # If this is set to a nonzero value, all tables are closed every flush_time seconds to free up resources and
  # synchronize unflushed data to disk.
  # This option is best used only on systems with minimal resources. flush_time=0
  
  # The minimum size of the buffer that is used for plain index scans, range index scans, and joins that do not use
  # indexes and thus perform full table scans. join_buffer_size=256K
  
  # The maximum size of one packet or any generated or intermediate string, or any parameter sent by the
  # mysql_stmt_send_long_data() C API function. max_allowed_packet=4M
  
  # If more than this many successive connection requests from a host are interrupted without a successful connection,
  # the server blocks that host from performing further connections. max_connect_errors=1000
  
  # Changes the number of file descriptors available to mysqld.
  # You should try increasing the value of this option if mysqld gives you the error "Too many open files". open_files_limit=4161
  
  # Set the query cache type. 0 for OFF, 1 for ON and 2 for DEMAND. query_cache_type = 1
  
  # If you see many sort_merge_passes per second in SHOW GLOBAL STATUS output, you can consider increasing the
  # sort_buffer_size value to speed up ORDER BY or GROUP BY operations that cannot be improved with query optimization
  # or improved indexing. sort_buffer_size=256K
  
  # The number of table definitions (from .frm files) that can be stored in the definition cache.
  # If you use a large number of tables, you can create a large table definition cache to speed up opening of tables.
  # The table definition cache takes less space and does not use file descriptors, unlike the normal table cache.
  # The minimum and default values are both 400. table_definition_cache=1400
  
  # Specify the maximum size of a row-based binary log event, in bytes.
  # Rows are grouped into events smaller than this size if possible. The value should be a multiple of 256. binlog_row_event_max_size=8K
  
  # If the value of this variable is greater than 0, a replication slave synchronizes its master.info file to disk.
  # (using fdatasync()) after every sync_master_info events. sync_master_info=10000
  
  # If the value of this variable is greater than 0, the MySQL server synchronizes its relay log to disk.
  # (using fdatasync()) after every sync_relay_log writes to the relay log. sync_relay_log=10000
  
  # If the value of this variable is greater than 0, a replication slave synchronizes its relay-log.info file to disk.
  # (using fdatasync()) after every sync_relay_log_info transactions. sync_relay_log_info=10000
  
  query_cache_limit = 30M collation-server = latin1_swedish_ci default_tmp_storage_engine = MYISAM
  
  
  myisam_use_mmap concurrent_insert = AUTO
  </code></pre>