Historical - changes to my.cnf

This post was shared on code.google.com many years ago but code.google has been shutdown. It describes work done by my team at Google. I am interested in the history of technology and with some spare time have been enable to republish it.

TODO - find the linked pages including:

  • MysqlHttp - we added an http server to mysql for exporting monitoring. I think this was implemented by Nick (last name?) who worked in Dublin
  • InnodbAsyncIo - this explains perf improvements we made for InnoDB
  • InnoDbIoTuning - explains more perf improvements we made for InnoDB

We added these options:

  • http_enable - start the embedded HTTP demon when ON, see MysqlHttp
  • http_port - port on which HTTP listens, see MysqlHttp
  • innodb_max_merged_io - max number of IO requests merged into one large request by a background IO thread
  • innodb_read_io_threads, innodb_write_io_threads - number of background IO threads for prefetch reads and dirty page writes, see InnodbAsyncIo
  • show_command_compatible_mysql4 - make output from some SHOW commands match that used by MySQL4
  • show_default_global - make SHOW STATUS use global statistics
  • global_status_update_interval - the interval at which per-thread stats are read for SHOW STATUS. When SHOW STATUS is run more frequently cached values are used rather than locking and reading data from each thread.
  • google_profile[=name] - enable profiling using Google Perftools and write output to this file. Server must have been compiled to use Google Perftools.
  • equality_propagation - enables use of equality propagation in the optimizer because the overhead was too much in a few releases (bug filed & fixed)
  • trim_trailing_blanks - trim trailing blanks on varchar fields when set
  • allow_view_trigger_sp_subquery - allow use of views, triggers, stored procedures and subqueries when set
  • allow_delayed_write - allow use of delayed insert and replace statements
  • local-infile-needs-file - LOAD DATA LOCAL INFILE requires the FILE privilege when set  
  • audit_log[=name] - log logins, queries against specified tables, and startup
  • audit_log_tables=name - log queries that use these tables to the audit log (comma separated)
  • log_root - log DML done by users with the SUPER privilege
  • repl_port[=#] - extra port on which mysqld listens for connections from users with SUPER and replication privileges
  • rpl_always_reconnect_on_error - slave IO thread always tries to reconnect on error when set
  • rpl_always_enter_innodb - slave SQL thread always enter innodb when set regardless of innodb concurrency ticket count
  • rpl_event_buffer_size=# - size of the per-connection buffer used on the master to copy events to a slave. Avoids allocating/deallocating a buffer for each event.
  • reserved_super_connections=# - number of reserved connections for users with SUPER privileges.
  • rpl_always_begin_event - always add a BEGIN event at the beginning of each transaction block written to the binlog. This fixes a bug.
  • rpl_semi_sync_enabled - enablesemisync replication on a master
  • rpl_semi_sync_slave_enabled - semisync replication on a slave
  • rpl_semi_sync_timeout - timeout in milliseconds for semisync replication in the master
  • rpl_semi_sync_trace_level - trace level for debugging for semisync replication
  • rpl_transaction_enabled - use transactional replication on a slave
  • innodb_crash_if_init_fails - crash if InnoDB initialization fails
  • innodb_io_capacity - number of disk IOPs the server can do, see InnodbIoTuning
  • innodb_extra_dirty_writes - flush dirty buffer pages when dirty pct is less than max dirty pct
  • connect_must_have_super - only connections with SUPER_ACL, REPL_SLAVE_ACL or REPL_CLIENT_ACL are accepted (yes, this is dynamic)
  • readonly_databases - prevents writes to any DB except for mysql
  • readonly_mysql - prevents writes to mysql DB will fail.
  • fixup_binlog_end_pos - fix for MySQL bug 23171 which updates the end_log_pos of  binlog events as they are written to the  bin log
  • log_slave_connects - log connect and disconnect messages for replication slaves
  • mapped_users - use the mapped_user table to map users to roles
  • xa_enabled - enable support for XA transactions (I like to disable this)
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