Changed in Percona Server 5.6

Percona Server 5.6 is based on MySQL 5.6 and incorporates many of the improvements found in Percona Server 5.5.

Features removed from Percona Server 5.6 that were available in Percona Server 5.5

Some features that were present in Percona Server 5.5 have been removed in Percona Server 5.6. These are:

Replaced features that were present in Percona Server 5.5

Some features that were present in Percona Server 5.5 have been replaced by a different implementation of the same/similar functionality in Percona Server 5.6. These are:

  • SHOW ENGINE INNODB STATUS section “OLDEST VIEW” has been replaced by the XTRADB_READ_VIEW INFORMATION_SCHEMA table.
  • SHOW ENGINE INNODB STATUS sections on memory usage for InnoDB/XtraDB hash tables has been replaced by the XTRADB_INTERNAL_HASH_TABLES INFORMATION_SCHEMA table.
  • The INNODB_RSEG table has been renamed to XTRADB_RSEG.
  • Fixed Size for the Read Ahead Area has been implemented differently. Buffer read-ahead area size is now precalculated once per buffer pool instance initialization instead of hardcoding it at 64MB (like it was done in previous Percona Server versions).
  • Response Time Distribution feature has been implemented as a plugin. It has the following changes from the 5.5 implementation: - the plugin requires installation before the feature can be used; - variable have_response_time_distribution has been removed. The presence of the feature can be determined by querying SHOW PLUGINS instead; - replication updates performed by the slave SQL threads are not tracked; - command SHOW QUERY_RESPONSE_TIME; has been removed in favor of QUERY_RESPONSE_TIME table; - command FLUSH QUERY_RESPONSE_TIME; has been replaced with query_response_time_flush variable.

Features available in Percona Server 5.5 that have been replaced with MySQL 5.6 features

Some Percona Server 5.5 features have been replaced by similar or equivalent MySQL 5.6 features, so we now keep the MySQL 5.6 implementations in Percona Server 5.6. These are:

  • Crash-Resistant Replication has been replaced by MySQL crash safe replication

  • Improved InnoDB I/O Scalability patches have been replaced by improvements and changes in MySQL 5.6, although Percona may make improvements in the future

  • InnoDB Data Dictionary Size Limit has been replaced by MySQL 5.6 using the existing table-definition-cache variable to limit the size of the InnoDB data dictionary.

  • Expand Table Import has been replaced by MySQL “InnoDB transportable tablespaces”

  • The InnoDB data dictionary INFORMATION_SCHEMA tables have been superseded by the MySQL implementations

  • XtraDB SYS_STATS persistent table and index statistics has been replaced by the MySQL 5.6 implementation

  • Dump/Restore of the Buffer Pool is now available in MySQL 5.6, so we have replaced the Percona Server implementation with the MySQL one. The upstream implementation doesn’t have the periodic dump feature, but it’s possible to set it up by using the event scheduler and the new innodb_buffer_pool_dump_now variable. The following example shows how to implement a periodic buffer pool dump every hour:

    mysql> CREATE EVENT automatic_bufferpool_dump
           ON SCHEDULE EVERY 1 HOUR
           DO
             SET global innodb_buffer_pool_dump_now=ON;
  • fast_index_creation (replaced by MySQL 5.6’s ALGORITHM= option).

  • Fast InnoDB Checksum has been deprecated after Percona Server 5.5.28-29.2 because the innodb_checksum_algorithm variable in MySQL 5.6 makes it redundant. If this feature was enabled, turning it off before the upgrade requires table(s) to be dump and imported, since it will fail to start on data files created when innodb_fast_checksums was enabled.

  • Handle BLOB End of Line feature has been replaced by MySQL 5.6 binary-mode configuration option.

  • Percona Server 5.5 implemented utf8_general50_ci and ucs2_general50_ci collations as a fix for the upstream bug: #27877. These are now being replaced by MySQL 5.6 utf8_general_mysql500_ci and ucs2_general_mysql500_ci collations.

  • Percona Server INFORMATION_SCHEMA _STATS tables in 5.5 have been replaced by new tables in MySQL 5.6: INNODB_SYS_TABLES, INNODB_SYS_INDEXES, INNODB_SYS_COLUMNS, INNODB_SYS_FIELDS, INNODB_SYS_FOREIGN, INNODB_SYS_FOREIGN_COLS, INNODB_SYS_TABLESTATS (although MySQL 5.6 does not have MYSQL_HANDLES_OPENED, instead it has REF_COUNT). Following tables haven’t been implemented in MySQL 5.6 but information is available in other tables: INNODB_SYS_STATS - use MYSQL.INNODB_(INDEX|TABLE)_STATS instead, INNODB_TABLE_STATS - use INNODB_SYS_TABLESTATS or MYSQL.INNODB_TABLE_STATS instead, and INNODB_INDEX_STATS - use MYSQL.INNODB_INDEX_STATS instead.

List of status variables that are no longer available in Percona Server 5.6

Following status variables available in Percona Server 5.5 are no longer present in Percona Server 5.6:

Status Variables Replaced by
Com_show_temporary_tables This variable has been removed together with the “SHOW [GLOBAL] TEMPORARY TABLES” statement, whose call number it was counting. The information about temporary tables is available via the INFORMATION_SCHEMA tables TEMPORARY_TABLES and GLOBAL_TEMPORARY_TABLES
Flashcache_enabled information if the Flashcache support has been enabled has not been ported to Percona Server 5.6
Innodb_adaptive_hash_cells this variable has not been ported to Percona Server 5.6
Innodb_adaptive_hash_heap_buffers this variable has not been ported to Percona Server 5.6
Innodb_adaptive_hash_hash_searches replaced by adaptive_hash_searches counter in INFORMATION_SCHEMA.INNODB_METRICS table
Innodb_adaptive_hash_non_hash_searches replaced by adaptive_hash_searches_btree counter in INFORMATION_SCHEMA.INNODB_METRICS table
Innodb_checkpoint_target_age replaced by MySQL 5.6 flushing implementation
Innodb_dict_tables InnoDB Data Dictionary Size Limit feature has been replaced by the new MySQL 5.6 table_definition_cache implementation
Innodb_master_thread_1_second_loops new InnoDB master thread behavior makes this variable redundant
Innodb_master_thread_10_second_loops new InnoDB master thread behavior makes this variable redundant
Innodb_master_thread_background_loops new InnoDB master thread behavior makes this variable redundant
Innodb_master_thread_main_flush_loops new InnoDB master thread behavior makes this variable redundant
Innodb_master_thread_sleeps replaced by innodb_master_thread_sleeps counter in INFORMATION_SCHEMA.INNODB_METRICS table
binlog_commits Binary Log Group Commit feature has been replaced with the MySQL 5.6 implementation that doesn’t have this status variable.
binlog_group_commits Binary Log Group Commit feature has been replaced with the MySQL 5.6 implementation that doesn’t have this status variable.

List of system variables that are no longer available in Percona Server 5.6

Following system variables available in Percona Server 5.5 are no longer present in Percona Server 5.6:

Warning

Percona Server 5.6 won’t be able to start if some of these variables are set in the server’s configuration file.

System Variables Feature Comment
fast_index_creation replaced by using MySQL’s ALGORITHM option
have_flashcache Information if the server has been compiled with the Flashcache support has not been ported to Percona Server 5.6
have_response_time_distribution Response Time Distribution feature has been ported to Percona Server 5.6 without this variable
innodb_adaptive_flushing_method replaced by MySQL 5.6 flushing implementation
innodb_blocking_buffer_pool_restore variable doesn’t have direct replacement in MySQL 5.6. Feature will be implemented in a future Percona Server 5.6 release
innodb_buffer_pool_restore_at_startup replaced by innodb_buffer_pool_load_at_startup
innodb_buffer_pool_shm_checksum variable has been deprecated and removed in Percona Server 5.5
innodb_buffer_pool_shm_key variable has been deprecated and removed in Percona Server 5.5
innodb_checkpoint_age_target replaced by MySQL 5.6 flushing implementation
innodb_dict_size_limit replaced by MySQL 5.6 new table_definition_cache implementation
innodb_doublewrite_file Configuration of the Doublewrite Buffer feature containing this variable has not been ported to Percona Server 5.6
innodb_fast_checksum replaced by innodb_checksum_algorithm
innodb_flush_neighbor_pages replaced by innodb_flush_neighbors
innodb_ibuf_accel_rate Configurable Insert Buffer feature containing this variable has not been ported to Percona Server 5.6
innodb_ibuf_active_contract Configurable Insert Buffer feature containing this variable has not been ported to Percona Server 5.6
innodb_ibuf_max_size Configurable Insert Buffer feature containing this variable has not been ported to Percona Server 5.6
innodb_import_table_from_xtrabackup replaced by MySQL transportable tablespaces
innodb_lazy_drop_table variable has been deprecated and removed in Percona Server 5.5
innodb_merge_sort_block_size replaced by innodb_sort_buffer_size
innodb_page_size replaced by innodb_page_size
innodb_read_ahead replaced by MySQL Read-Ahead Algorithm implementation, innodb_random_read_ahead
innodb_recovery_stats InnoDB Recovery Stats feature containing this variable has not been ported to Percona Server 5.6
innodb_recovery_update_relay_log replaced by relay-log-recovery
innodb_stats_auto_update replaced by innodb_stats_auto_recalc
innodb_stats_update_need_lock variable has not been ported to Percona Server 5.6
innodb_thread_concurrency_timer_based InnoDB timer-based Concurrency Throttling feature containing this variable has not been ported to Percona Server 5.6
innodb_use_sys_stats_table variable has been replaced by Persistent Optimizer Statistics implementation in MySQL 5.6
log_slow_admin_statements the upstream variable has the same functionality
log_slow_slave_statements the upstream variable has the same functionality
optimizer_fix this variable has been deprecated and removed in Percona Server 5.5
query_response_time_range_base Response Time Distribution feature containing this variable has been ported to Percona Server 5.6, but requires plugin installation in order to work. More information can be found in Response Time Distribution documentation.
query_response_time_stats Response Time Distribution feature containing this variable has been ported to Percona Server 5.6, but requires plugin installation in order to work. More information can be found in Response Time Distribution documentation.
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