changed_in_56.rst

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:

• SHOW [GLOBAL] TEMPORARY TABLES functionality is now only available via the INFORMATION_SCHEMA tables :table:`TEMPORARY_TABLES` and :table:`GLOBAL_TEMPORARY_TABLES`.
• InnoDB timer-based Concurrency Throttling
• InnoDB Recovery Stats
• Rows_read counters in :ref:`slow_extended` and SHOW PROCESSLIST had a very fuzzy meaning so they were removed.

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Some features that were present in |Percona Server| 5.5 have been replaced by a different implementation of the same/similar functionality in |Percona Server| 5.6.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• SHOW ENGINE INNODB STATUS section "OLDEST VIEW" has been replaced by the :table:`XTRADB_READ_VIEW` INFORMATION_SCHEMA table.
• SHOW ENGINE INNODB STATUS sections on memory usage for InnoDB/XtraDB hash tables has been replaced by the :table:`XTRADB_INTERNAL_HASH_TABLES` INFORMATION_SCHEMA table.
• The :table:`INNODB_RSEG` table has been renamed to :table:`XTRADB_RSEG`.
• :ref:`buff_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).
• :ref:`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 :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 :table:`QUERY_RESPONSE_TIME` table; - command FLUSH QUERY_RESPONSE_TIME; has been replaced with :variable:`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Some |Percona Server| 5.5 features have been replaced by similar or equivalent |MySQL| 5.6 features, so we now keep the |MySQL| 5.6 implementations in |Percona Server| 5.6.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).

• :ref:`Fast InnoDB Checksum <ps55:innodb_fast_checksum_page>` has been deprecated after |Percona Server| 5.5.28-29.2 because the :variable:`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 dumped and imported, since it will fail to start on data files created when :variable:`innodb_fast_checksum` was enabled. As an alternative you can use :program:`innochecksum` from |MySQL| 5.7 as described in this blogpost.

• :ref:`Handle BLOB End of Line <ps55:mysql_remove_eol_carret>` 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: :mysqlbug:`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.

Features ported from |Percona Server| 5.5 to |Percona Server| 5.6

Following features were ported from |Percona Server| 5.5 to |Percona Server| 5.6:

Feature Ported	Version
:ref:`threadpool`	:rn:`5.6.10-60.2`
:ref:`atomic_fio`	:rn:`5.6.11-60.3`
:ref:`innodb_io_page`	:rn:`5.6.11-60.3`
:ref:`innodb_numa_support`	:rn:`5.6.11-60.3`
:ref:`log_warning_suppress`	:rn:`5.6.11-60.3`
:ref:`improved_memory_engine`	:rn:`5.6.11-60.3`
:ref:`maximum_binlog_files`	:rn:`5.6.11-60.3`
:ref:`log_connection_error`	:rn:`5.6.11-60.3`
:ref:`error_pad`	:rn:`5.6.11-60.3`
:ref:`show_slave_status_nolock`	:rn:`5.6.11-60.3`
:ref:`udf_percona_toolkit`	:rn:`5.6.11-60.3`
:ref:`innodb_fake_changes_page`	:rn:`5.6.11-60.3`
:ref:`innodb_kill_idle_trx`	:rn:`5.6.11-60.3`
:ref:`enforce_engine`	:rn:`5.6.11-60.3`
:ref:`psaas_utility_user`	:rn:`5.6.11-60.3`
:ref:`secure_file_priv_extended`	:rn:`5.6.11-60.3`
:ref:`expanded_option_modifiers`	:rn:`5.6.11-60.3`
:ref:`changed_page_tracking`	:rn:`5.6.11-60.3`
:ref:`pam_plugin`	:rn:`5.6.11-60.3`
:ref:`user_stats`	:rn:`5.6.11-60.3`
:ref:`slow_extended`	:rn:`5.6.11-60.3`
:ref:`innodb_show_status`	:rn:`5.6.11-60.3`
:ref:`innodb_deadlocks_page`	:rn:`5.6.11-60.3`
:ref:`mysql_syslog`	:rn:`5.6.11-60.3`
:ref:`show_engines`	:rn:`5.6.11-60.3`
:ref:`thread_based_profiling`	:rn:`5.6.11-60.3`
:ref:`buff_read_ahead_area`	:rn:`5.6.13-60.5`
:ref:`innodb_split_buf_pool_mutex`	:rn:`5.6.13-60.6`
:ref:`innodb_adaptive_hash_index_partitions_page`	:rn:`5.6.13-60.6`
:ref:`handlersocket_page`	:rn:`5.6.17-66.0`
:ref:`response_time_distribution`	:rn:`5.6.21-69.0`

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:

.. tabularcolumns:: |p{8cm}|p{7.5cm}|

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 :table:`TEMPORARY_TABLES` and :table:`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	:ref:`InnoDB Data Dictionary Size Limit <ps55:innodb_dict_size_limit_page>` 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	:ref:`Binary Log Group Commit <ps55:binary_group_commit>` feature has been replaced with the |MySQL| 5.6 implementation that doesn't have this status variable.
binlog_group_commits	:ref:`Binary Log Group Commit <ps55:binary_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.

.. tabularcolumns:: |p{8cm}|p{7.5cm}|

System Variables	Feature Comment
:variable:`fast_index_creation`	replaced by using MySQL's ALGORITHM option
:variable:`have_flashcache`	Information if the server has been compiled with the Flashcache support has not been ported to |Percona Server| 5.6
:variable:`have_response_time_distribution`	:ref:`Response Time Distribution <ps55:response_time_distribution>` feature has been ported to |Percona Server| 5.6 without this variable
:variable:`innodb_adaptive_flushing_method`	replaced by MySQL 5.6 flushing implementation
:variable:`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
:variable:`innodb_buffer_pool_restore_at_startup`	replaced by innodb_buffer_pool_load_at_startup
:variable:`innodb_buffer_pool_shm_checksum`	variable has been deprecated and removed in |Percona Server| 5.5
:variable:`innodb_buffer_pool_shm_key`	variable has been deprecated and removed in |Percona Server| 5.5
:variable:`innodb_checkpoint_age_target`	replaced by MySQL 5.6 flushing implementation
:variable:`innodb_dict_size_limit`	replaced by |MySQL| 5.6 new table_definition_cache implementation
:variable:`innodb_doublewrite_file`	:ref:`Configuration of the Doublewrite Buffer <ps55:innodb_doublewrite_path>` feature containing this variable has not been ported to |Percona Server| 5.6
:variable:`innodb_fast_checksum`	replaced by innodb_checksum_algorithm
:variable:`innodb_flush_neighbor_pages`	replaced by innodb_flush_neighbors
:variable:`innodb_ibuf_accel_rate`	:ref:`Configurable Insert Buffer <ps55:innodb_insert_buffer>` feature containing this variable has not been ported to |Percona Server| 5.6
:variable:`innodb_ibuf_active_contract`	:ref:`Configurable Insert Buffer <ps55:innodb_insert_buffer>` feature containing this variable has not been ported to |Percona Server| 5.6
:variable:`innodb_ibuf_max_size`	:ref:`Configurable Insert Buffer <ps55:innodb_insert_buffer>` feature containing this variable has not been ported to |Percona Server| 5.6
:variable:`innodb_import_table_from_xtrabackup`	replaced by MySQL transportable tablespaces
:variable:`innodb_lazy_drop_table`	variable has been deprecated and removed in |Percona Server| 5.5
:variable:`innodb_merge_sort_block_size`	replaced by innodb_sort_buffer_size
:variable:`innodb_page_size`	replaced by innodb_page_size
:variable:`innodb_read_ahead`	replaced by MySQL Read-Ahead Algorithm implementation, innodb_random_read_ahead
:variable:`innodb_recovery_stats`	:ref:`InnoDB Recovery Stats <ps55:innodb_recovery_patches>` feature containing this variable has not been ported to |Percona Server| 5.6
:variable:`innodb_recovery_update_relay_log`	replaced by relay-log-recovery
:variable:`innodb_stats_auto_update`	replaced by innodb_stats_auto_recalc
:variable:`innodb_stats_update_need_lock`	variable has not been ported to |Percona Server| 5.6
:variable:`innodb_thread_concurrency_timer_based`	:ref:`InnoDB timer-based Concurrency Throttling <ps55:innodb_thread_concurrency_timer_based_page>` feature containing this variable has not been ported to |Percona Server| 5.6
:variable:`innodb_use_sys_stats_table`	variable has been replaced by Persistent Optimizer Statistics implementation in |MySQL| 5.6
:variable:`log_slow_admin_statements`	the upstream variable has the same functionality
:variable:`log_slow_slave_statements`	the upstream variable has the same functionality
:variable:`optimizer_fix`	this variable has been deprecated and removed in |Percona Server| 5.5
:variable:`query_response_time_range_base`	:ref:`Response Time Distribution <ps55: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 :ref:`response_time_distribution` documentation.
:variable:`query_response_time_stats`	:ref:`Response Time Distribution <ps55: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 :ref:`response_time_distribution` documentation.