This page lists the system variables available for configuring InnoDB's behavior, performance, buffers, and logs.
This page documents system variables related to the InnoDB storage engine. For options that are not system variables, see InnoDB Options.
See Server System Variables for a complete list of system variables and instructions on setting them.
Also see the Full list of MariaDB options, system and status variables.
have_innodbDescription: If the server supports , are set to YES, otherwise are set to NO. Removed in , use the table or instead.
Scope: Global
Dynamic: No
Removed:
ignore_builtin_innodbDescription: Setting this to 1 results in the built-in InnoDB storage engine being ignored. In some versions of MariaDB, XtraDB is the default and is always present, so this variable is ignored and setting it results in a warning. From to , when InnoDB was the default instead of XtraDB, this variable needed to be set. Usually used in conjunction with the option to use the InnoDB plugin.
Command line: --ignore-builtin-innodb
Scope: Global
innodb_adaptive_checkpointDescription: Replaced with . Controls adaptive checkpointing. InnoDB's fuzzy checkpointing can cause stalls, as many dirty blocks are flushed at once as the checkpoint age nears the maximum. Adaptive checkpointing aims for more consistent flushing, approximately modified age / maximum checkpoint age. Can result in larger transaction log files
reflex Similar to flushing but flushes blocks constantly and contiguously based on the oldest modified age. If the age exceeds 1/2 of the maximum age capacity, flushing are weak contiguous. If the age exceeds 3/4, flushing are strong. Strength can be adjusted by the variable .
innodb_adaptive_flushingDescription: If set to 1, the default, the server will dynamically adjust the flush rate of dirty pages in the . This assists to reduce brief bursts of I/O activity. If set to 0, adaptive flushing will only take place when the limit specified by is reached.
Command line: --innodb-adaptive-flushing={0|1}
Scope: Global
innodb_adaptive_flushing_lwmDescription: Adaptive flushing is enabled when this low water mark percentage of the capacity is reached. Takes effect even if is disabled.
Command line: --innodb-adaptive-flushing-lwm=#
Scope: Global
Dynamic: Yes
innodb_adaptive_flushing_methodDescription: Determines the method of flushing dirty blocks from the InnoDB . If set to native or 0, the original InnoDB method is used. The maximum checkpoint age is determined by the total length of all transaction log files. When the checkpoint age reaches the maximum checkpoint age, blocks are flushed. This can cause lag if there are many updates per second and many blocks with an almost identical age need to be flushed. If set to estimate or 1, the default, the oldest modified age are compared with the maximum age capacity. If it's more than 1/4 of this age, blocks are flushed every second. The number of blocks flushed is determined by the number of modified blocks, the LSN progress speed and the average age of all modified blocks. It's therefore independent of the for the 1-second loop, but not entirely so for the 10-second loop. If set to keep_average or 2, designed specifically for SSD cards, a shorter loop cycle is used in an attempt to keep the I/O rate constant. Removed in /XtraDB 5.6 and replaced with InnoDB flushing method from MySQL 5.6.
innodb_adaptive_hash_indexDescription: If set to 1, the default until , the hash index is enabled. Based on performance testing (), the InnoDB adaptive hash index helps performance in mostly read-only workloads, and could slow down performance in other environments, especially , , , or operations.
Command line: --innodb-adaptive-hash-index={0|1}
Scope: Global
innodb_adaptive_hash_index_partitionsDescription: Specifies the number of partitions for use in adaptive searching. If set to 1, no extra partitions are created. XtraDB-only. From (which uses InnoDB as default instead of XtraDB), this is an alias for to allow for easier upgrades.
Command line: innodb-adaptive-hash-index-partitions=#
Scope: Global
innodb_adaptive_hash_index_partsDescription: Specifies the number of partitions for use in adaptive searching. If set to 1, no extra partitions are created.
Command line: innodb-adaptive-hash-index-parts=#
Scope: Global
Dynamic: No
innodb_adaptive_max_sleep_delayDescription: Maximum time in microseconds to automatically adjust the value to, based on the workload. Useful in extremely busy systems with hundreds of thousands of simultaneous connections. 0 disables any limit. Deprecated and ignored from .
Command line: --innodb-adaptive-max-sleep-delay=#
Scope: Global
innodb_additional_mem_pool_sizeDescription: Size in bytes of the memory pool used for storing information about internal data structures. Defaults to 8MB, if your application has many tables and a large structure, and this is exceeded, operating system memory are allocated and warning messages written to the error log, in which case you should increase this value. Deprecated in and removed in along with InnoDB's internal memory allocator.
Command line: --innodb-additional-mem-pool-size=#
Scope: Global
innodb_alter_copy_bulkDescription: Allow bulk insert operation for copy alter operation.
Scope: Global
Dynamic: Yes
Data Type: boolean
innodb_api_bk_commit_intervalDescription: Time in seconds between auto-commits for idle connections using the InnoDB memcached interface (not implemented in MariaDB).
Command line: --innodb-api-bk-commit-interval=#
Scope: Global
Dynamic: Yes
innodb_api_disable_rowlockDescription: For use with MySQL's memcached (not implemented in MariaDB)
Command line: --innodb-api-disable-rowlock={0|1}
Scope: Global
Dynamic: No
innodb_api_enable_binlogDescription: For use with MySQL's memcached (not implemented in MariaDB)
Command line: --innodb-api-enable-binlog={0|1}
Scope: Global
Dynamic: No
innodb_api_enable_mdlDescription: For use with MySQL's memcached (not implemented in MariaDB)
Command line: --innodb-api-enable-mdl={0|1}
Scope: Global
Dynamic: No
innodb_api_trx_levelDescription: For use with MySQL's memcached (not implemented in MariaDB)
Command line: --innodb-api-trx-level=#
Scope: Global
Dynamic: Yes
innodb_auto_lru_dumpDescription: Renamed since XtraDB 5.5.10-20.1, which was in turn replaced by in .
Command line: --innodb-auto-lru-dump=#
Removed: XtraDB 5.5.10-20.1
innodb_autoextend_incrementDescription: Size in MB to increment an auto-extending shared tablespace file when it becomes full. If was set to 1, this setting does not apply to the resulting per-table tablespace files, which are automatically extended in their own way.
Command line: --innodb-autoextend-increment=#
Scope: Global
innodb_autoinc_lock_modeDescription: The lock mode that is used when generating values for InnoDB tables.
Valid values are:
0 is the traditional lock mode.
innodb_background_scrub_data_check_intervalDescription: Check if spaces needs scrubbing every seconds. See . Deprecated and ignored from .
Command line: --innodb-background-scrub-data-check-interval=#
Scope: Global
Dynamic: Yes
innodb_background_scrub_data_compressedDescription: Enable scrubbing of compressed data by background threads (same as encryption_threads). See . Deprecated and ignored from .
Command line: --innodb-background-scrub-data-compressed={0|1}
Scope: Global
Dynamic: Yes
innodb_background_scrub_data_intervalDescription: Scrub spaces that were last scrubbed longer than this number of seconds ago. See . Deprecated and ignored from .
Command line: --innodb-background-scrub-data-interval=#
Scope: Global
Dynamic: Yes
innodb_background_scrub_data_uncompressedDescription: Enable scrubbing of uncompressed data by background threads (same as encryption_threads). See . Deprecated and ignored from .
Command line: --innodb-background-scrub-data-uncompressed={0|1}
Scope: Global
Dynamic: Yes
innodb_blocking_buffer_pool_restoreDescription: If set to 1 (0 is default), XtraDB will wait until the least-recently used (LRU) dump is completely restored upon restart before reporting back to the server that it has successfully started up. Available with XtraDB only, not InnoDB.
Command line: innodb-blocking-buffer-pool-restore={0|1}
Scope: Global
innodb_buf_dump_status_frequencyDescription: Determines how often (as a percent) the buffer pool dump status should be printed in the logs. For example, 10 means that the buffer pool dump status is printed when every 10% of the number of buffer pool pages are dumped. The default is 0 (only start and end status is printed).
Command line: --innodb-buf-dump-status-frequency=#
Scope: Global
innodb_buffer_pool_chunk_sizeDescription: Chunk size used for dynamically resizing the . Note that changing this setting can change the size of the buffer pool. When is used this value is effectively rounded up to the next multiple of . See . From , the variable is autosized based on the .
Command line: --innodb-buffer-pool-chunk-size=#
Scope: Global
innodb_buffer_pool_dump_at_shutdownDescription: Whether to record pages cached in the on server shutdown, which reduces the length of the warmup the next time the server starts. The related specifies whether the buffer pool is automatically warmed up at startup.
Command line: --innodb-buffer-pool-dump-at-shutdown={0|1}
Scope: Global
Dynamic: Yes
innodb_buffer_pool_dump_nowDescription: Immediately records pages stored in the . The related does the reverse, and will immediately warm up the buffer pool.
Command line: --innodb-buffer-pool-dump-now={0|1}
Scope: Global
Dynamic: Yes
innodb_buffer_pool_dump_pctDescription: Dump only the hottest N% of each .
Command line: --innodb-buffer-pool-dump-pct={0|1}
Scope: Global
Dynamic: Yes
innodb_buffer_pool_evictDescription: Evict pages from the buffer pool. If set to "uncompressed" then all uncompressed pages are evicted from the buffer pool. Variable to be used only for testing. Only exists in DEBUG builds.
Command line: --innodb-buffer-pool-evict=#
Scope: Global
Dynamic: Yes
innodb_buffer_pool_filenameDescription: The file that holds the list of page numbers set by and .
Command line: --innodb-buffer-pool-filename=file
Scope: Global
Dynamic: Yes
innodb_buffer_pool_instancesDescription: If is set to more than 1GB, innodb_buffer_pool_instances divides the buffer pool into the specified number of instances. The default was 1 in , but for large systems with buffer pools of many gigabytes, many instances could help reduce contention concurrency through . The default is 8 in MariaDB 10 (except on Windows 32-bit, where it varies according to , or from , where it is set to 1 if < 1GB). Each instance manages its own data structures and takes an equal portion of the total buffer pool size, so for example if innodb_buffer_pool_size is 4GB and innodb_buffer_pool_instances is set to 4, each instance are 1GB. Each instance should ideally be at least 1GB in size. Starting with , performance improvements intended to reduce the overhead of context-switching between buffer pools changed the recommended number of innodb_buffer_pool_instances to one for every 128GB of buffer pool size. Based on these changes, the variable is deprecated and ignored from , where the buffer pool runs in a single instance regardless of size.
Command line: --innodb-buffer-pool-instances=#
innodb_buffer_pool_load_abortDescription: Aborts the process of restoring contents started by or .
Command line: --innodb-buffer-pool-load-abort={0|1}
Scope: Global
Dynamic: Yes
innodb_buffer_pool_load_at_startupDescription: Specifies whether the is automatically warmed up when the server starts by loading the pages held earlier. The related specifies whether pages are saved at shutdown. If the buffer pool is large and taking a long time to load, increasing at startup may help.
Command line: --innodb-buffer-pool-load-at-startup={0|1}
Scope: Global
innodb_buffer_pool_load_nowDescription: Immediately warms up the by loading the stored data pages. The related does the reverse, and immediately records pages stored in the buffer pool.
Command line: --innodb-buffer-pool-load-now={0|1}
Scope: Global
Dynamic: Yes
innodb_buffer_pool_load_pages_abortDescription: Number of pages during a buffer pool load to process before signaling . Debug builds only.
Command line: --innodb-buffer-pool-load-pages-abort=#
Scope: Global
Dynamic: Yes
innodb_buffer_pool_populateDescription: When set to 1 (0 is default), XtraDB will preallocate pages in the buffer pool on starting up so that NUMA allocation decisions are made while the buffer cache is still clean. XtraDB only. This option was made ineffective in . Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-buffer-pool-populate={0|1}
Scope: Global
innodb_buffer_pool_restore_at_startupDescription: Time in seconds between automatic buffer pool dumps. If set to a non-zero value, XtraDB will also perform an automatic restore of the at startup. If set to 0, automatic dumps are not performed, nor automatic restores on startup. Replaced by in .
Command line: innodb-buffer-pool-restore-at-startup
Scope: Global
innodb_buffer_pool_shm_checksumDescription: Used with Percona's SHM buffer pool patch in XtraDB 5.5. Was shortly deprecated and removed in XtraDB 5.6. XtraDB only.
Command line: innodb-buffer-pool-shm-checksum={0|1}
Scope: Global
Dynamic: No
innodb_buffer_pool_shm_keyDescription: Used with Percona's SHM buffer pool patch in XtraDB 5.5. Later deprecated in XtraDB 5.5, and removed in XtraDB 5.6.
Command line: innodb-buffer-pool-shm-key={0|1}
Scope: Global
Dynamic: No
innodb_buffer_pool_sizeDescription: InnoDB buffer pool size in bytes. The primary value to adjust on a database server with entirely/primarily tables, can be set up to 80% of the total memory in these environments. See the for more on setting this variable, and also if doing so dynamically.
Command line: --innodb-buffer-pool-size=#
Scope: Global
innodb_buffer_pool_size_auto_minDescription: Minimum innodb_buffer_pool_size in bytes for dynamic shrinking on memory pressure. Only affects Linux. If a memory pressure event is reported by Linux, the innodb_buffer_pool_size may be automatically shrunk towards this value. By default, set to , that is, memory pressure events will be ignored. 0 sets no minimum value.
Command line: --innodb-buffer-pool-size-auto-min=#
Scope: Global
innodb_buffer_pool_size_maxDescription: Maximum innodb_buffer_pool_size value.
Command line: --innodb-buffer-pool-size-max=#
Scope: Global
Dynamic: No
innodb_change_buffer_dumpDescription: If set, causes the contents of the InnoDB change buffer to be dumped to the server error log at startup. Only available in debug builds.
Scope: Global
Dynamic: No
Data Type: boolean
innodb_change_buffer_max_sizeDescription: Maximum size of the as a percentage of the total buffer pool. The default is 25%, and this can be increased up to 50% for servers with high write activity, and lowered down to 0 for servers used exclusively for reporting.
Command line: --innodb-change-buffer-max-size=#
Scope: Global
Dynamic: Yes
innodb_change_bufferingDescription: Sets how change buffering is performed. See for details on the settings. Deprecated and ignored from .
Command line: --innodb-change-buffering=#
Scope: Global
Dynamic: Yes
innodb_change_buffering_debugDescription: If set to 1, an debug flag is set. 1 forces all changes to the change buffer, while 2 causes a crash at merge. 0, the default, indicates no flag is set. Only available in debug builds.
Command line: --innodb-change-buffering-debug=#
innodb_checkpoint_age_targetDescription: The maximum value of the checkpoint age. If set to 0, has no effect. Removed in /XtraDB 5.6 and replaced with InnoDB flushing method from MySQL 5.6.
Command line: innodb-checkpoint-age-target=#
Scope: Global
innodb_checksum_algorithmDescription: Specifies how the InnoDB tablespace checksum is generated and verified.
innodb: Backwards compatible with earlier versions (<= ). Deprecated in , , and removed in . If really needed, data files can still be converted with .
crc32: A newer, faster algorithm, but incompatible with earlier versions. Tablespace blocks are converted to the new format over time, meaning that a mix of checksums may be present.
innodb_checksumsDescription: By default, performs checksum validation on all pages read from disk, which provides extra fault tolerance. You would usually want this set to 1 in production environments, although setting it to 0 can provide marginal performance improvements. Deprecated and functionality replaced by in , and should be removed to avoid conflicts. ON is equivalent to --innodb_checksum_algorithm=innodb and OFF to --innodb_checksum_algorithm=none.
Command line: --innodb-checksums
innodb_cleaner_lsn_age_factorDescription: XtraDB has enhanced page cleaner heuristics, and with these in place, the default InnoDB adaptive flushing may be too aggressive. As a result, a new LSN age factor formula has been introduced, controlled by this variable. The default setting, high_checkpoint, uses the new formula, while the alternative, legacy, uses the original algorithm. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: --innodb-cleaner-lsn-age-factor=value
Scope: Global
innodb_cmp_per_index_enabledDescription: If set to ON (OFF is default), per-index compression statistics are stored in the table. These are expensive to record, so this setting should only be changed with care, such as for performance tuning on development or replica servers.
Command line: --innodb-cmp-per-index-enabled={0|1}
Scope: Global
innodb_commit_concurrencyDescription: Limit to the number of transaction threads that can commit simultaneously. 0, the default, imposes no limit. While you can change from one positive limit to another at runtime, you cannot set this variable to 0, or change it from 0, while the server is running. Deprecated and ignored from .
Command line: --innodb-commit-concurrency=#
Scope: Global
Dynamic: Yes
innodb_compression_algorithmDescription: Compression algorithm used for . The supported values are:
none: Pages are not compressed.
zlib: Pages are compressed using the bundled compression algorithm.
innodb_compression_defaultDescription: Whether or not is enabled by default for new tables.
The default value is OFF, which means new tables are not compressed.
See for more information.
Command line:
innodb_compression_failure_threshold_pctDescription: Specifies the percentage cutoff for expensive compression failures during updates to a table that uses , after which free space is added to each new compressed page, dynamically adjusted up to the level set by . Zero disables checking of compression efficiency and adjusting padding.
See for more information.
Command line: --innodb-compression-failure-threshold-pct=#
innodb_compression_levelDescription: Specifies the default level of compression for tables that use .
Only a subset of InnoDB page compression algorithms support compression levels. If an InnoDB page compression algorithm does not support compression levels, then the compression level value is ignored.
The compression level can be set to any value between 1 and 9. The default compression level is 6. The range goes from the fastest to the most compact, which means that
innodb_compression_pad_pct_maxDescription: The maximum percentage of reserved free space within each compressed page for tables that use . Reserved free space is used when the page's data is reorganized and might be recompressed. Only used when is not zero, and the rate of compression failures exceeds its setting.
See for more information.
Command line: --innodb-compression-pad-pct-max=#
innodb_concurrency_ticketsDescription: Number of times a newly-entered thread can enter and leave until it is again subject to the limitations of and may possibly be queued. Deprecated and ignored from .
Command line: --innodb-concurrency-tickets=#
Scope: Global
Dynamic: Yes
innodb_corrupt_table_actionDescription: What action to perform when a corrupt table is found. XtraDB only.
When set to assert, the default, XtraDB will intentionally crash the server when it detects corrupted data in a single-table tablespace, with an assertion failure.
When set to warn, it will pass corruption as corrupt table instead of crashing, and disable all further I/O (except for deletion) on the table file.
innodb_data_file_bufferingDescription: Whether to enable the file system cache for data files. Set to OFF by default, are set to ON if is set to fsync, littlesync, nosync, or (Windows specific) normal.
Command line: --innodb-data-file-buffering={0|1}
innodb_data_file_pathDescription: Individual data files, paths and sizes. The value of is joined to each path specified by innodb_data_file_path to get the full directory path. If innodb_data_home_dir is an empty string, absolute paths can be specified here. A file size is specified (with K for kilobytes, M for megabytes and G for gigabytes). Also whether or not to autoextend the data file, and whether or not to on startup may also be specified.
Command line: --innodb-data-file-path=name
Scope: Global
innodb_data_file_write_throughDescription: Whether writes to InnoDB data files (including the temporary tablespace) are write through. Set to OFF by default, are set to ON if is set to O_DSYNC. On systems that support FUA it may make sense to enable write-through, to avoid extra system calls.
Command line: --innodb-data-file-write-through={0|1}
Scope: Global
innodb_data_home_dirDescription: Directory path for all data files in the shared tablespace (assuming is not enabled). File-specific information can be added in , as well as absolute paths if innodb_data_home_dir is set to an empty string.
Command line: --innodb-data-home-dir=path
Scope: Global
Dynamic: No
innodb_deadlock_detectDescription: By default, the InnoDB deadlock detector is enabled. If set to off, deadlock detection is disabled and MariaDB will rely on instead. This may be more efficient in systems with high concurrency as deadlock detection can cause a bottleneck when a number of threads have to wait for the same lock.
Command line: --innodb-deadlock-detect
Scope: Global
Dynamic: Yes
innodb_deadlock_reportDescription: How to report deadlocks (if ).
off: Do not report any details of deadlocks.
basic: Report transactions and waiting locks.
innodb_default_page_encryption_keyDescription: Encryption key used for page encryption.
See and for more information.
Command line: --innodb-default-page-encryption-key=#
Scope: Global
innodb_default_encryption_key_idDescription: ID of encryption key used by default to encrypt InnoDB tablespaces.
See and for more information.
Command line: --innodb-default-encryption-key-id=#
Scope: Global, Session
innodb_default_row_formatDescription: Specifies the default to be used for InnoDB tables. The compressed row format cannot be set as the default.
See for more information.
Command line: --innodb-default-row-format=value
innodb_defragmentDescription: When set to 1 (the default is 0), InnoDB defragmentation is enabled. When set to FALSE, all existing defragmentation are paused and new defragmentation commands will fail. Paused defragmentation commands will resume when this variable is set to true again. See .
Command line: --innodb-defragment={0|1}
Scope: Global
innodb_defragment_fill_factorDescription:. Indicates how full defragmentation should fill a page. Together with ensures defragmentation won’t pack the page too full and cause page split on the next insert on every page. The variable indicating more defragmentation gain is the one effective. See .
Command line: --innodb-defragment-fill-factor=#
Scope: Global
Dynamic: Yes
innodb_defragment_fill_factor_n_recsDescription: Number of records of space that defragmentation should leave on the page. This variable, together with , is introduced so defragmentation won't pack the page too full and cause page split on the next insert on every page. The variable indicating more defragmentation gain is the one effective. See .
Command line: --innodb-defragment-fill-factor-n-recs=#
Scope: Global
innodb_defragment_frequencyDescription: Maximum times per second for defragmenting a single index. This controls the number of times the defragmentation thread can request X_LOCK on an index. The defragmentation thread will check whether 1/defragment_frequency (s) has passed since it last worked on this index, and put the index back in the queue if not enough time has passed. The actual frequency can only be lower than this given number. See .
Command line: --innodb-defragment-frequency=#
Scope: Global
innodb_defragment_n_pagesDescription: Number of pages considered at once when merging multiple pages to defragment. See .
Command line: --innodb-defragment-n-pages=#
Scope: Global
Dynamic: Yes
innodb_defragment_stats_accuracyDescription: Number of defragment stats changes there are before the stats are written to persistent storage. Defaults to zero, meaning disable defragment stats tracking. See .
Command line: --innodb-defragment-stats-accuracy=#
Scope: Global
Dynamic: Yes
innodb_dict_size_limitDescription: Size in bytes of a soft limit the memory used by tables in the data dictionary. Once this limit is reached, XtraDB will attempt to remove unused entries. If set to 0, the default and standard InnoDB behavior, there is no limit to memory usage. Removed in /XtraDB 5.6 and replaced by MySQL 5.6's new implementation.
Command line: innodb-dict-size-limit=#
Scope: Global
innodb_disable_sort_file_cacheDescription: If set to 1 (0 is default), the operating system file system cache for merge-sort temporary files is disabled.
Command line: --innodb-disable-sort-file-cache={0|1}
Scope: Global
innodb_disallow_writesDescription: Tell InnoDB to stop any writes to disk.
Command line: None
Scope: Global
Dynamic: Yes
innodb_doublewriteDescription: If set to ON, the default, to improve fault tolerance first stores data to a before writing it to data file. Disabling will provide a marginal performance improvement, and assumes that writes of are atomic. fast is available from , and is like ON, but writes are not synchronized to data files. The deprecated start-up parameter will cause innodb_doublewrite=ON to be changed to innodb_doublewrite=fast, which will prevent InnoDB from making any durable writes to data files. This would normally be done right before the log checkpoint LSN is updated. Depending on the file systems being used and their configuration, this may or may not be safe.
The value innodb_doublewrite=fast differs from the previous combination of innodb_doublewrite=ON and innodb_flush_method=O_DIRECT_NO_FSYNC by always invoking os_file_flush() on the doublewrite buffer itself in buf_dblwr_t::flush_buffered_writes_completed(). This should be safer when there are multiple doublewrite batches between checkpoints.
Typically, once per second, buf_flush_page_cleaner() would write out up to innodb_io_capacity pages and advance the log checkpoint. Also typically, innodb_io_capacity>128, which is the size of the doublewrite buffer in pages. Should os_file_flush_func() not be invoked between doublewrite batches, writes could be reordered in an unsafe way.
innodb_doublewrite_fileDescription: The absolute or relative path and filename to a dedicated tablespace for the . In heavy workloads, the doublewrite buffer can impact heavily on the server, and moving it to a different drive will reduce contention on random reads. Since the doublewrite buffer is mostly sequential writes, a traditional HDD is a better choice than SSD. This Percona XtraDB variable has not been ported to XtraDB 5.6.
Command line: innodb-doublewrite-file=filename
Scope: Global
innodb_empty_free_list_algorithmDescription: XtraDB 5.6.13-61 introduced an algorithm to assist with reducing mutex contention when the buffer pool free list is empty, controlled by this variable. If set to backoff, the default until , the new algorithm are used. If set to legacy, the original InnoDB algorithm are used. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades. See for the reasons this was changed back to legacy in XtraDB 5.6.36-82.0. When upgrading from 10.0 to 10.1 (>= 10.1.24), for large buffer pools the default will remain backoff, while for small ones it are changed to legacy.
Command line: innodb-empty-free-list-algorithm=value
innodb_enable_unsafe_group_commitDescription: Unneeded after XtraDB 1.0.5. If set to 0, the default, InnoDB will keep transactions between the transaction log and s in the same order. Safer, but slower. If set to 1, transactions can be group-committed, but there is no guarantee of the order being kept, and a small risk of the two logs getting out of sync. In write-intensive environments, can lead to a significant improvement in performance.
Command line: --innodb-enable-unsafe-group-commit
Scope: Global
innodb_encrypt_logDescription: Enables encryption of the . This also enables encryption of some temporary files created internally by InnoDB, such as those used for merge sorts and row logs.
See and for more information.
Command line: --innodb-encrypt-log
innodb_encrypt_tablesDescription: Enables automatic encryption of all InnoDB tablespaces.
OFF - Disables table encryption for all new and existing tables that have the table option set to DEFAULT.
ON - Enables table encryption for all new and existing tables that have the table option set to DEFAULT
innodb_encrypt_temporary_tablesDescription: Enables automatic encryption of the InnoDB .
See and for more information.
Command line: --innodb-encrypt-temporary-tables={0|1}
innodb_encryption_rotate_key_ageDescription: Re-encrypt in background any page having a key older than this number of key versions. When setting up encryption, this variable must be set to a non-zero value. Otherwise, when you enable encryption through MariaDB won't be able to automatically encrypt any unencrypted tables.
See and for more information.
Command line: --innodb-encryption-rotate-key-age=#
innodb_encryption_rotation_iopsDescription: Use this many iops for background key rotation operations performed by the background encryption threads.
See and for more information.
Command line: --innodb-encryption-rotation_iops=#
innodb_encryption_threadsDescription: Number of background encryption threads performing background key rotation and . When setting up encryption, this variable must be set to a non-zero value. Otherwise, when you enable encryption through MariaDB won't be able to automatically encrypt any unencrypted tables. Recommended never be set higher than 255.
See and for more information.
Command line: --innodb-encryption-threads=#
innodb_extra_rsegmentsDescription: Removed in XtraDB 5.5 and replaced by . Usually there is one rollback segment protected by single mutex, a source of contention in high write environments. This option specifies a number of extra user rollback segments. Changing the default will make the data readable by XtraDB only, and is incompatible with InnoDB. After modifying, the server must be slow-shutdown. If there is existing data, it must be dumped before changing, and re-imported after the change has taken effect.
Command line: --innodb-extra-rsegments=#
Scope: Global
innodb_extra_undoslotsDescription: Usually, InnoDB has 1024 undo slots in its rollback segment, so 1024 transactions can run in parallel. New transactions will fail if all slots are used. Setting this variable to 1 expands the available undo slots to 4072. Not recommended unless you get the Warning: cannot find a free slot for an undo log error in the error log, as it makes data files unusable for ibbackup, or MariaDB servers not run with this option. See also .
Command line: --innodb-extra-undoslots={0|1}
Scope: Global
innodb_fake_changesDescription: From until , XtraDB-only option that enables the fake changes feature. In , setting up or restarting a replica can cause a replication reads to perform more slowly, as MariaDB is single-threaded and needs to read the data before it can execute the queries. This can be speeded up by prefetching threads to warm the server, replaying the statements and then rolling back at commit. This however has an overhead from locking rows only then to undo changes at rollback. Fake changes attempts to reduce this overhead by reading the rows for INSERT, UPDATE and DELETE statements but not updating them. The rollback is then very fast with little or nothing to do. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades. Not present in and beyond.
Command line: --innodb-fake-changes={0|1}
innodb_fast_checksumDescription: Implements a more CPU efficient XtraDB checksum algorithm, useful for write-heavy loads with high I/O. If set to 1 on a server with tables that have been created with it set to 0, reads are slower, so tables should be recreated (dumped and reloaded). XtraDB will fail to start if set to 0 and there are tables created while set to 1. Replaced with in /XtraDB 5.6.
Command line: --innodb-fast-checksum={0|1}
innodb_fast_shutdownDescription: The shutdown mode.
0 - InnoDB performs a slow shutdown, including full purge (before , not always, due to ) and change buffer merge. Can be very slow, even taking hours in extreme cases.
1 - the default, performs a fast shutdown, not performing a full purge or an insert buffer merge.
innodb_fatal_semaphore_wait_thresholdDescription: In MariaDB, the fatal semaphore timeout is configurable. This variable sets the maximum number of seconds for semaphores to time out in InnoDB.
Command line: --innodb-fatal-semaphore-wait-threshold=#
Scope: Global
Dynamic: No
innodb_file_formatDescription: File format for new tables. Can either be Antelope, the default and the original format, or Barracuda, which supports . Note that this value is also used when a table is re-created with an which requires a table copy. See for more on the file formats. Removed in 10.3.1 and restored as a deprecated and unused variable in 10.4.3 for compatibility purposes.
Command line: --innodb-file-format=value
Scope: Global
innodb_file_format_checkDescription: If set to 1, the default, checks the shared tablespace file format tag. If this is higher than the current version supported by XtraDB/InnoDB (for example Barracuda when only Antelope is supported), XtraDB/InnoDB will not start. If it the value is not higher, XtraDB/InnoDB starts correctly and the value is set to this value. If innodb_file_format_check is set to 0, no checking is performed. See for more on the file formats.
Command line: --innodb-file-format-check={0|1}
Scope: Global
innodb_file_format_maxDescription: The highest file format. This is set to the value of the file format tag in the shared tablespace on startup (see ). If the server later creates a higher table format, innodb_file_format_max is set to that value. See for more on the file formats.
Command line: --innodb-file-format-max=value
Scope: Global
innodb_file_per_tableDescription: If set to ON, then new tables are created with their own . If set to OFF, then new tables are created in the instead. is only available with file-per-table tablespaces. Note that this value is also used when a table is re-created with an which requires a table copy. Deprecated in as there's no benefit to setting to OFF, the original InnoDB default.
Command line: --innodb-file-per-table
innodb_fill_factorDescription: Percentage of B-tree page filled during bulk insert (sorted index build). Used as a hint rather than an absolute value. Setting to 70, for example, reserves 30% of the space on each B-tree page for the index to grow in future.
Command line: --innodb-fill-factor=#
Scope: Global
innodb_flush_log_at_timeoutDescription: Interval in seconds to write and flush the . Before MariaDB 10, this was fixed at one second, which is still the default, but this can now be changed. It's usually increased to reduce flushing and avoid impacting performance of binary log group commit.
Scope: Global
Dynamic: Yes
Data Type: numeric
innodb_flush_log_at_trx_commitDescription: Set to 1, along with for the greatest level of fault tolerance. The value of determines whether this variable can be reset with a SET statement or not.
1 The default, the log buffer is written to the file and a flush to disk performed after each transaction. This is required for full ACID compliance.
0 Nothing is done on commit; rather the log buffer is written and flushed to the
innodb_flush_methodDescription: flushing method. Windows always uses async_unbuffered and this variable then has no effect. On Unix, before , by default fsync() is used to flush data and logs. Adjusting this variable can give performance improvements, but behavior differs widely on different filesystems, and changing from the default has caused problems in some situations, so test and benchmark carefully before adjusting. In MariaDB, Windows recognises and correctly handles the Unix methods, but if none are specified it uses own default - unbuffered write (analog of O_DIRECT) + syncs (e.g FileFlushBuffers()) for all files.
O_DSYNC - O_DSYNC is used to open and flush logs, and fsync() to flush the data files.
O_DIRECT
innodb_flush_neighbor_pagesDescription: Determines whether, when dirty pages are flushed to the data file, neighboring pages in the data file are flushed at the same time. If set to none, the feature is disabled. If set to area, the default, the standard InnoDB behavior is used. For each page to be flushed, dirty neighboring pages are flushed too. If there's little head seek delay, such as SSD or large enough write buffer, one of the other two options may be more efficient. If set to cont, for each page to be flushed, neighboring contiguous blocks are flushed at the same time. Being contiguous, a sequential I/O is used, unlike the random I/O used in area. Replaced by in /XtraDB 5.6.
Command line: innodb-flush-neighbor-pages=value
innodb_flush_neighborsDescription: Determines whether flushing a page from the will flush other dirty pages in the same group of pages (extent). In high write environments, if flushing is not aggressive enough, it can fall behind resulting in higher memory usage, or if flushing is too aggressive, cause excess I/O activity. SSD devices, with low seek times, would be less likely to require dirty neighbor flushing to be set. Since an attempt is made under Windows and Linux to determine SSD status which was exposed in . This variable is ignored for table spaces that are detected as stored on SSD (and the 0 behavior applies).
1: The default, flushes contiguous dirty pages in the same extent from the buffer pool.
innodb_flush_syncDescription: If set to ON, the default, the setting is ignored for I/O bursts occurring at checkpoints.
Command line: --innodb-flush-sync={0|1}
Scope: Global
Dynamic: Yes
innodb_flushing_avg_loopsDescription: Determines how quickly adaptive flushing will respond to changing workloads. The value is the number of iterations that a previously calculated flushing state snapshot is kept. Increasing the value smooths and slows the rate that the flushing operations change, while decreasing it causes flushing activity to spike quickly in response to workload changes.
Command line: --innodb-flushing-avg-loops=#
Scope: Global
innodb_force_load_corruptedDescription: Set to 0 by default, if set to 1, are permitted to load tables marked as corrupt. Only use this to recover data you can't recover any other way, or in troubleshooting. Always restore to 0 when the returning to regular use. Given that in aims to allow any metadata for a missing or corrupted table to be dropped, and given that and and related tasks made DDL operations crash-safe, the parameter no longer serves any purpose and was removed in .
Command line: --innodb-force-load-corrupted
innodb_force_primary_keyDescription: If set to 1 (0 is default) CREATE TABLEs without a primary or unique key where all keyparts are NOT NULL will not be accepted, and will return an error.
Command line: --innodb-force-primary-key
Scope: Global
innodb_force_recoveryDescription: crash recovery mode. 0 is the default. The other modes are for recovery purposes only, and no data can be changed while another mode is active. Some queries relying on indexes are also blocked. See for more on mode specifics.
Command line: --innodb-force-recovery=#
Scope: Global
innodb_foreground_preflushDescription: Before XtraDB 5.6.13-61.0, if the checkpoint age is in the sync preflush zone while a thread is writing to the , it will try to advance the checkpoint by issuing a flush list flush batch if this is not already being done. XtraDB has enhanced page cleaner tuning, and may already be performing furious flushing, resulting in the flush simply adding unneeded mutex pressure. Instead, the thread now waits for the flushes to finish, and then has two options, controlled by this variable. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
exponential_backoff - thread sleeps while it waits for the flush list flush to occur. The sleep time randomly progressively increases, periodically reset to avoid runaway sleeps.
innodb_ft_aux_tableDescription: Diagnostic variable intended only to be set at runtime. It specifies the qualified name (for example test/ft_innodb) of an InnoDB table that has a , and after being set the INFORMATION_SCHEMA tables , , INNODB_FT_CONFIG, , and will contain search index information for the specified table.
Command line: --innodb-ft-aux-table=value
Scope: Global
innodb_ft_cache_sizeDescription: Cache size available for a parsed document while creating an InnoDB .
Command line: --innodb-ft-cache-size=#
Scope: Global
Dynamic: No
innodb_ft_enable_diag_printDescription: If set to 1, additional search diagnostic output is enabled.
Command line: --innodb-ft-enable-diag-print={0|1}
Scope: Global
Dynamic: Yes
innodb_ft_enable_stopwordDescription: If set to 1, the default, a set of is associated with an InnoDB when it is created. The stopword list comes from the table set by the session variable , if set, otherwise the global variable , if that is set, or the if neither variable is set.
Command line: --innodb-ft-enable-stopword={0|1}
Scope: Global
innodb_ft_max_token_sizeDescription: Maximum length of words stored in an InnoDB . A larger limit will increase the size of the index, slowing down queries, but permit longer words to be searched for. In most normal situations, longer words are unlikely search terms.
Command line: --innodb-ft-max-token-size=#
Scope: Global
Dynamic: No
innodb_ft_min_token_sizeDescription: Minimum length of words stored in an InnoDB . A smaller limit will increase the size of the index, slowing down queries, but permit shorter words to be searched for. For data stored in a Chinese, Japanese or Korean , a value of 1 should be specified to preserve functionality.
Command line: --innodb-ft-min-token-size=#
Scope: Global
innodb_ft_num_word_optimizeDescription: Number of words processed during each on an InnoDB . To ensure all changes are incorporated, multiple OPTIMIZE TABLE statements could be run in case of a substantial change to the index.
Command line: --innodb-ft-num-word-optimize=#
Scope: Global
Dynamic: Yes
innodb_ft_result_cache_limitDescription: Limit in bytes of the InnoDB query result cache per fulltext query. The latter stages of the full-text search are handled in memory, and limiting this prevents excess memory usage. If the limit is exceeded, the query returns an error.
Command line: --innodb-ft-result-cache-limit=#
Scope: Global
Dynamic: Yes
innodb_ft_server_stopword_tableDescription: Table name containing a list of stopwords to ignore when creating an InnoDB , in the format db_name/table_name. The specified table must exist before this option is set, and must be an InnoDB table with a single column, a named VALUE. See also .
Command line: --innodb-ft-server-stopword-table=db_name/table_name
Scope: Global
innodb_ft_sort_pll_degreeDescription: Number of parallel threads used when building an InnoDB . See also .
Command line: --innodb-ft-sort-pll-degree=#
Scope: Global
Dynamic: No
innodb_ft_total_cache_sizeDescription:Total memory allocated for the cache for all InnoDB tables. A force sync is triggered if this limit is exceeded.
Command line: --innodb-ft-total-cache-size=#
Scope: Global
Dynamic: No
innodb_ft_user_stopword_tableDescription: Table name containing a list of stopwords to ignore when creating an InnoDB , in the format db_name/table_name. The specified table must exist before this option is set, and must be an InnoDB table with a single column, a named VALUE. See also .
Command line: --innodb-ft-user-stopword-table=db_name/table_name
Scope: Session
innodb_ibuf_accel_rateDescription: Allows the insert buffer activity to be adjusted. The following formula is used: [real activity] = [default activity] * (innodb_io_capacity/100) * (innodb_ibuf_accel_rate/100). As innodb_ibuf_accel_rate is increased from its default value of 100, the lowest setting, insert buffer activity is increased. See also . This Percona XtraDB variable has not been ported to XtraDB 5.6.
Command line: innodb-ibuf-accel-rate=#
Scope: Global
innodb_ibuf_active_contractDescription: Specifies whether the insert buffer can be processed before it's full. If set to 0, the standard InnoDB method is used, and the buffer is not processed until it's full. If set to 1, the default, the insert buffer can be processed before it is full. This Percona XtraDB variable has not been ported to XtraDB 5.6.
Command line: innodb-ibuf-active-contract=#
Scope: Global
innodb_ibuf_max_sizeDescription: Maximum size in bytes of the insert buffer. Defaults to half the size of the so you may want to reduce if you have a very large buffer pool. If set to 0, the insert buffer is disabled, which will cause all secondary index updates to be performed synchronously, usually at a cost to performance. This Percona XtraDB variable has not been ported to XtraDB 5.6.
Command line: innodb-ibuf-max-size=#
Scope: Global
innodb_idle_flush_pctDescription: Up to what percentage of dirty pages should be flushed when innodb finds it has spare resources to do so. Has had no effect since merging InnoDB 5.7 from mysql-5.7.9 (). Deprecated in , , and removed in .
Command line: --innodb-idle-flush-pct=#
Scope: Global
innodb_immediate_scrub_data_uncompressedDescription: Enable scrubbing of data. See .
Command line: --innodb-immediate-scrub-data-uncompressed={0|1}
Scope: Global
Dynamic: Yes
innodb_import_table_from_xtrabackupDescription: If set to 1, permits importing of .ibd files exported with the --export option. Previously named innodb_expand_import. Removed in /XtraDB 5.6 and replaced with MySQL 5.6's transportable tablespaces.
Command line: innodb-import-table-from-xtrabackup=#
Scope: Global
innodb_instant_alter_column_allowedDescription:
If a table is altered using ALGORITHM=INSTANT, it can force the table to use a non-canonical format: A hidden metadata record at the start of the clustered index is used to store each column's DEFAULT value. This makes it possible to add new columns that have default values without rebuilding the table. Starting with , a BLOB in the hidden metadata record is used to store column mappings. This makes it possible to drop or reorder columns without rebuilding the table. This also makes it possible to add columns to any position or drop columns from any position in the table without rebuilding the table. If a column is dropped without rebuilding the table, old records will contain garbage in that column's former position, and new records are written with NULL values, empty strings, or dummy values.
This is generally not a problem. However, there may be cases where you want to avoid putting a table into this format. For example, to ensure that future UPDATE operations after an ADD COLUMN are performed in-place, to reduce write amplification. (Instantly added columns are essentially always variable-length.) Also avoid bugs similar to
innodb_instrument_semaphoresDescription: Enable semaphore request instrumentation. This could have some effect on performance but allows better information on long semaphore wait problems.
Command line: --innodb-instrument-semaphores={0|1}
Scope: Global
Dynamic: Yes
innodb_io_capacityDescription: Limit on I/O activity for InnoDB background tasks, including merging data from the insert buffer and flushing pages. Should be set to around the number of I/O operations per second that system can handle, based on the type of drive/s being used. You can also set it higher when the server starts to help with the extra workload at that time, and then reduce for normal use. Ideally, opt for a lower setting, as at higher value data is removed from the buffers too quickly, reducing the effectiveness of caching. See also .
See for more information.
Command line: --innodb-io-capacity=#
innodb_io_capacity_maxDescription: Upper limit to which InnoDB can extend in case of emergency. See for more information.
Command line: --innodb-io-capacity-max=#
Scope: Global
Dynamic: Yes
innodb_kill_idle_transactionDescription: Time in seconds before killing an idle XtraDB transaction. If set to 0 (the default), the feature is disabled. Used to prevent accidental user locks. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Scope: Global
Dynamic: Yes
Data Type:
innodb_large_prefixDescription: If set to 1, tables that use specific are permitted to have index key prefixes up to 3072 bytes (for 16k pages, ). If not set, the limit is 767 bytes.
This applies to the and row formats.
Removed in 10.3.1 and restored as a deprecated and unused variable in 10.4.3 for compatibility purposes.
innodb_lazy_drop_tableDescription: Deprecated and removed in XtraDB 5.6. processing can take a long time when is set to 1 and there's a large . If innodb_lazy_drop_table is set to 1 (0 is default), XtraDB attempts to optimize processing by deferring the dropping of related pages from the until there is time, only initially marking them.
Command line: innodb-lazy-drop-table={0|1}
innodb_lock_schedule_algorithmDescription: Removed in due to problems with the VATS implementation (). Specifies the algorithm that InnoDB uses to decide which of the waiting transactions should be granted the lock once it has been released. The possible values are: FCFS (First-Come-First-Served) where locks are granted in the order they appear in the lock queue and VATS (Variance-Aware-Transaction-Scheduling) where locks are granted based on the Eldest-Transaction-First heuristic. Note that VATS should not be used with , and InnoDB will refuse to start if VATS is used with Galera. It is also not recommended to set to VATS even in the general case (). From , the value was changed to FCFS and a warning produced when using Galera.
innodb_lock_wait_timeoutDescription: Time in seconds that an InnoDB transaction waits for an InnoDB record lock (or table lock) before giving up with the error ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction. When this occurs, the statement (not transaction) is rolled back. The whole transaction can be rolled back if the option is used. Increase this for data warehousing applications or where other long-running operations are common, or decrease for OLTP and other highly interactive applications. This setting does not apply to deadlocks, which InnoDB detects immediately, rolling back a deadlocked transaction. 0 means no wait. See . Setting to 100000000 or more (from , 100000000 is the maximum) means the timeout is infinite.
Command line: --innodb-lock-wait-timeout=#
innodb_locking_fake_changesDescription: From to , XtraDB-only option that if set to OFF, fake transactions (see ) don't take row locks. This is an experimental feature to attempt to deal with drawbacks in fake changes blocking real locks. It is not safe for use in all environments. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: --innodb-locking-fake-changes
Scope: Global
innodb_locks_unsafe_for_binlogDescription: Set to 0 by default, in which case XtraDB/InnoDB uses . If set to 1, gap locking is disabled for searches and index scans. Deprecated in , and removed in , use instead.
Command line: --innodb-locks-unsafe-for-binlog
Scope: Global
innodb_log_arch_dirDescription: The directory for archiving. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: --innodb-log-arch-dir=name
Scope: Global
Dynamic: No
innodb_log_arch_expire_secDescription: Time in seconds since the last change after which the archived should be deleted. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: --innodb-log-arch-expire-sec=#
Scope: Global
Dynamic: Yes
innodb_log_archiveDescription: Whether or not archiving is enabled. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: --innodb-log-archive={0|1}
Scope: Global
Dynamic: Yes
innodb_log_block_sizeDescription: Size in bytes of the records. Generally 512, the default, or 4096, are the only two useful values. If the server is restarted and this value is changed, all old log files need to be removed. Should be set to 4096 for SSD cards or if is set to ALL_O_DIRECT on ext4 filesystems. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-log-block-size=#
innodb_log_buffer_sizeDescription: Size in bytes of the buffer for writing files to disk. Increasing this means larger transactions can run without needing to perform disk I/O before committing.
Command line: --innodb-log-buffer-size=#
Scope: Global
Dynamic: No
innodb_log_checkpoint_nowDescription: Write back dirty pages from the and update the log checkpoint. Prior to , , was only available in debug builds. Introduced in order to force checkpoints before a backup, allowing mariadb-backup to create much smaller incremental backups. However, this comes at the cost of heavy I/O usage and it is now disabled by default.
Command line: --innodb-log-checkpoint{=1|0}
Scope: Global
innodb_log_checksum_algorithmDescription: Experimental feature (as of ), this variable specifies how to generate and verify checksums. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
none - No checksum. A constant value is instead written to logs, and no checksum validation is performed.
innodb - The default, and the original InnoDB algorithm. This is inefficient, but compatible with all MySQL, MariaDB and Percona versions that don't support other checksum algorithms.
innodb_log_checksumsDescription: If set to 1, the CRC32C for Innodb or innodb_log_checksum_algorithm for XtraDB algorithm is used for pages. If disabled, the checksum field contents are ignored. From , the variable is deprecated, and checksums are always calculated, as previously, the InnoDB redo log used the slow innodb algorithm, but with hardware or SIMD assisted CRC-32C computation being available, there is no reason to allow checksums to be disabled on the redo log.
Command line: innodb-log-checksums={0|1}
Scope: Global
innodb_log_compressed_pagesDescription: Whether or not images of recompressed pages are stored in the . Deprecated and ignored from .
Command line: --innodb-log-compressed-pages={0|1}
Scope: Global
Dynamic: Yes
innodb_log_file_bufferingDescription: Whether the file system cache for ib_logfile0 is enabled. In , MariaDB disabled the file system cache on the InnoDB write-ahead log file (ib_logfile0) by default on Linux. With in particular, writing to the log via the file system cache typically improves throughput, especially on slow storage or at a small number of concurrent transactions. For other values of innodb_flush_log_at_trx_commit, direct writes were observed to be mostly but not always faster. Whether it pays off to disable the file system cache on the log may depend on the type of storage, the workload, and the operating system kernel version. If the server is started up with , the value are changed to ON. Will be set to OFF if is set to O_DSYNC. On Linux, when the physical block size cannot be determined to be a power of 2 between 64 and 4096 bytes, the file system cache cannot be disabled, and innodb_log_file_buffering=ON cannot be changed. Linux and Windows only.
Command line: --innodb-log-file-buffering={0|1}
innodb_log_file_mmapDescription: Whether ib_logfile0 resides in persistent memory or should initially be memory-mapped. When using the default innodb_log_buffer_size=2m, mariadb-backup --backup would spend a lot of time re-reading and re-parsing the log. For reading the log file during mariadb-backup --backup, it is beneficial to memory-map the entire ib_logfile0 to the address space (typically 48 bits or 256 TiB) and read it from there, both during --backup and --prepare. OFF by default on most platforms, to avoid aggressive read-ahead of the entire ib_logfile0 in when only a tiny portion would be accessed. On Linux and FreeBSD the default is innodb_log_file_mmap=ON, because those platforms define a specific mmap(2) option for enabling such read-ahead and therefore it can be assumed that the default wouldbe on-demand paging. This parameter will only have impact on the initial InnoDB startup and recovery. Any writes to the log will use regular I/O, except when the ib_logfile0 is stored in a specially configured file system that is backed by persistent memory (Linux "mount -o dax").
Command line: --innodb-log-file-mmap{=0|1}
innodb_log_file_sizeDescription: Size in bytes of each file in the log group. The combined size can be no more than 512GB. Larger values mean less disk I/O due to less flushing checkpoint activity, but also slower recovery from a crash. In , crash recovery has been improved and shouldn't run out of memory, so the default has been increased. It can safely be set higher to reduce checkpoint flushing, even larger than .From the variable is dynamic, and the server no longer needs to be restarted for the resizing to take place. Unless the log is located in a persistent memory file system (PMEM), an attempt to innodb_log_file_size to less than are refused. Log resizing can be aborted by killing the connection that is executing the SET GLOBAL statement.
Command line: --innodb-log-file-size=#
Scope: Global
innodb_log_file_write_throughDescription: Whether each write to ib_logfile0 is write through (disabling any caching, as in O_SYNC or O_DSYNC). Set to OFF by default, are set to ON if is set to O_DSYNC. On systems that support FUA it may make sense to enable write-through, to avoid extra system calls.
Command line: --innodb-log-file-write-through={0|1}
Scope: Global
innodb_log_files_in_groupDescription: Number of physical files in the . Deprecated and ignored from
Command line: --innodb-log-files-in-group=#
Scope: Global
Dynamic: No
innodb_log_group_home_dirDescription: Path to the files. If none is specified, files named ib_logfile0 and so on, with a size of are created in the data directory.
Command line: --innodb-log-group-home-dir=path
Scope: Global
Dynamic: No
innodb_log_optimize_ddlDescription: Whether activity should be reduced when natively creating indexes or rebuilding tables. Reduced logging requires additional page flushing and interferes with . Enabling this may slow down backup and cause delay due to page flushing. Deprecated and ignored from . Deprecated (but not ignored) from , and .
Command line: --innodb-log-optimize-ddl={0|1}
Scope: Global
innodb_log_spin_wait_delayDescription: Delay between log buffer spin lock polls (0 to use a blocking latch). Specifically, enables a spin lock that will execute that many MY_RELAX_CPU() operations (such as the x86 PAUSE instruction) between successive attempts of acquiring the spin lock. On some hardware with certain workloads (observed on write intensive workloads on NUMA systems), the default setting results in a significant amount of time being spent in native_queued_spin_lock_slowpath() in the Linux kernel, plus context switching between user and kernel address space, in which case changing from the default (for example, setting to 50), may result in a performance improvement.
Command line: --innodb-log-spin-wait-delay=#
Scope: Global
innodb_log_write_ahead_sizeDescription: write ahead unit size to avoid read-on-write. Should match the OS cache block IO size. Removed in , and instead on Linux and Windows, the physical block size of the underlying storage is detected and used. Reintroduced in and later versions. On Linux and Windows, the default or the specified innodb_log_write_ahead_size are automatically adjusted to not be less than the physical block size (if it can be determined).
Command line: --innodb-log-write-ahead-size=#
Scope: Global
innodb_lru_flush_sizeDescription: Number of pages to flush on LRU eviction. Changes in , , , , and made this setting superfluous, and it is no longer used.
Command line: --innodb-lru-flush-size=#
Scope: Global
innodb_lru_scan_depthDescription: Specifies how far down the buffer pool least-recently used (LRU) list the cleaning thread should look for dirty pages to flush. This process is performed once a second. In an I/O intensive-workload, can be increased if there is spare I/O capacity, or decreased if in a write-intensive workload with little spare I/O capacity.
See for more information.
Command line: --innodb-lru-scan-depth=#
innodb_max_bitmap_file_sizeDescription: Limit in bytes of the changed page bitmap files. For faster incremental backup with , XtraDB tracks pages with changes written to them according to the and writes the information to special changed page bitmap files. These files are rotated when the server restarts or when this limit is reached. XtraDB only. See also and .
Deprecated and ignored in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-max-bitmap-file-size=#
innodb_max_changed_pagesDescription: Limit to the number of changed page bitmap files (stored in the ). Zero is unlimited. See and . Previously named innodb_changed_pages_limit. XtraDB only.
Deprecated and ignored in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-max-changed-pages=#
innodb_max_dirty_pages_pctDescription: Maximum percentage of unwritten (dirty) pages in the buffer pool.
See for more information.
Command line: --innodb-max-dirty-pages-pct=#
Scope: Global
innodb_max_dirty_pages_pct_lwmDescription: Low water mark percentage of dirty pages that will enable preflushing to lower the dirty page ratio. The value 0 (default) means 'refer to '. (Note that 0 meant 0 in 10.5.7 to 10.5.8, but was then reverted back to "same as innodb_max_dirty_pages_pct" again in 10.5.9)
See for more information.
Command line: --innodb-max-dirty-pages-pct-lwm=#
innodb_max_purge_lagDescription: When purge operations are lagging on a busy server, setting innodb_max_purge_lag can help. By default set to 0, no lag, the figure is used to calculate a time lag for each INSERT, UPDATE, and DELETE when the system is lagging. InnoDB keeps a list of transactions with delete-marked index records due to UPDATE and DELETE statements. The length of this list is purge_lag, and the calculation, performed every ten seconds, is as follows: ((purge_lag/innodb_max_purge_lag)×10)–5 microseconds.
Command line: --innodb-max-purge-lag=#
Scope: Global
innodb_max_purge_lag_delayDescription: Maximum delay in milliseconds imposed by the setting. If set to 0, the default, there is no maximum.
Command line: --innodb-max-purge-lag-delay=#
Scope: Global
Dynamic: Yes
innodb_max_purge_lag_waitDescription: Wait until History list length is below the specified limit.
Command line: --innodb-max-purge-wait=#
Scope: Global
Dynamic: Yes
innodb_max_undo_log_sizeDescription: If an undo tablespace is larger than this, it is marked for truncation if is set.
Command line: --innodb-max-undo-log-size=#
Scope: Global
Dynamic: Yes
innodb_merge_sort_block_sizeDescription: Size in bytes of the block used for merge sorting in fast index creation. Replaced in /XtraDB 5.6 by .
Command line: innodb-merge-sort-block-size=#
Scope: Global
Dynamic: Yes
innodb_mirrored_log_groupsDescription: Unused. Restored as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Deprecated:
Removed: -
innodb_mtflush_threadsDescription: Sets the number of threads to use in Multi-Threaded Flush operations. For more information, see .
InnoDB's multi-thread flush feature was deprecated in and removed from . In later versions of MariaDB, use system variable instead.
See for more information.
innodb_monitor_disableDescription: Disables the specified counters in the table.
Command line: --innodb-monitor-disable=string
Scope: Global
Dynamic: Yes
innodb_monitor_enableDescription: Enables the specified counters in the table.
Command line: --innodb-monitor-enable=string
Scope: Global
Dynamic: Yes
innodb_monitor_resetDescription: Resets the count value of the specified counters in the table to zero.
Command line: --innodb-monitor-reset=string
Scope: Global
Dynamic: Yes
innodb_monitor_reset_allDescription: Resets all values for the specified counters in the table.
Command line: ---innodb-monitor-reset-all=string
Scope: Global
Dynamic: Yes
innodb_numa_interleaveDescription: Whether or not to use the NUMA interleave memory policy to allocate the . Before , required that MariaDB be compiled on a NUMA-enabled Linux system.
Command line: innodb-numa-interleave={0|1}
Scope: Global
Dynamic: No
innodb_old_blocks_pctDescription: Percentage of the to use for the old block sublist.
Command line: --innodb-old-blocks-pct=#
Scope: Global
Dynamic: Yes
innodb_old_blocks_timeDescription: Time in milliseconds an inserted block must stay in the old sublist after its first access before it can be moved to the new sublist. '0' means "no delay". Setting a non-zero value can help prevent full table scans clogging the . See also .
Command line: --innodb-old-blocks-time=#
Scope: Global
Dynamic: Yes
innodb_online_alter_log_max_sizeDescription: The maximum size for temporary log files during online DDL (data and index structure changes). The temporary log file is used for each table being altered, or index being created, to store data changes to the table while the process is underway. The table is extended by up to the limit set by this variable. If this limit is exceeded, the online DDL operation fails and all uncommitted changes are rolled back. A lower value reduces the time a table could lock at the end of the operation to apply all the log's changes, but also increases the chance of the online DDL changes failing.
Command line: --innodb-online-alter-log-max-size=#
Scope: Global
innodb_open_filesDescription: Maximum .ibd files MariaDB can have open at the same time. Only applies to systems with multiple XtraDB/InnoDB tablespaces, and is separate to the table cache and . The default, if is disabled, is 300 or the value of , whichever is higher. It will also auto-size up to the default value if it is set to a value less than 10.
Command line: --innodb-open-files=#
Scope: Global
innodb_optimize_fulltext_onlyDescription: When set to 1 (0 is default), will only process InnoDB data. Only intended for use during fulltext index maintenance.
Command line: --innodb-optimize-fulltext-only={0|1}
Scope: Global
innodb_page_cleanersDescription: Number of page cleaner threads. The default is 4, but the value are set to the number of if this is lower. If set to 1, only a single cleaner thread is used, as was the case until . Cleaner threads flush dirty pages from the , performing flush list and least-recently used (LRU) flushing. Deprecated and ignored from , as the original reasons for splitting the buffer pool have mostly gone away.
See for more information.
Command line:
innodb_page_sizeDescription: Specifies the page size in bytes for all InnoDB tablespaces. The default, 16k, is suitable for most uses.
A smaller InnoDB page size might work more effectively in a situation with many small writes (OLTP), or with SSD storage, which usually has smaller block sizes.
A larger InnoDB page size can provide a larger .
innodb_pass_corrupt_tableRemoved: XtraDB 5.5 - renamed .
innodb_prefix_index_cluster_optimizationDescription: Enable prefix optimization to sometimes avoid cluster index lookups. Deprecated and ignored from , as the optimization is now always enabled.
Command line: --innodb-prefix-index-cluster-optimization={0|1}
Scope: Global
Dynamic: Yes
innodb_print_all_deadlocksDescription: If set to 1 (0 is default), all InnoDB transaction deadlock information is written to the .
Command line: --innodb-print-all-deadlocks={0|1}
Scope: Global
innodb_purge_batch_sizeDescription: Number of pages to purge in one batch from the history list. Together with has a small effect on tuning.
Command line: --innodb-purge-batch-size=#
Scope: Global
Dynamic: No
innodb_purge_rseg_truncate_frequencyDescription: Frequency with which undo records are purged. Set by default to every 128 times, reducing this increases the frequency at which rollback segments are freed. See also . The motivation for introducing this in MySQL seems to have been to avoid stalls due to freeing undo log pages or truncating undo log tablespaces. In MariaDB, should be a much lighter operation because it will not involve any log checkpoint, hence this is deprecated and ignored from , , , , and . ()
Command line: -- innodb-purge-rseg-truncate-frequency=#
Scope: Global
innodb_purge_threadsDescription: Number of background threads dedicated to InnoDB purge operations. The range is 1 to 32. At least one background thread is always used. Setting to a value greater than 1 creates that many separate purge threads. This can improve efficiency in some cases, such as when performing DML operations on many tables. See also .
Command line: --innodb-purge-threads=#
Scope: Global
innodb_random_read_aheadDescription: Originally, random read-ahead was always set as an optimization technique, but was removed in . innodb_random_read_ahead permits it to be re-instated if set to 1 (0) is default.
Command line: --innodb-random-read-ahead={0|1}
Scope: Global
innodb_read_aheadDescription: If set to linear, the default, XtraDB/InnoDB will automatically fetch remaining pages if there are enough within the same extent that can be accessed sequentially. If set to none, read-ahead is disabled. random has been removed and is now ignored, while both sets to both linear and random. Also see for more control on read-aheads. Removed in /XtraDB 5.6 and replaced by MySQL 5.6's .
Command line: innodb-read-ahead=value
innodb_read_ahead_thresholdDescription: Minimum number of pages InnoDB must read sequentially from an extent of 64 before initiating an asynchronous read for the following extent.
Command line: --innodb-read-ahead-threshold=#
Scope: Global
Dynamic: Yes
innodb_read_io_threadsDescription: Prior to , this was simply the number of I/O threads for InnoDB reads. From , asynchronous I/O functionality in the InnoDB Background Thread Pool replaces the old InnoDB I/O Threads. This variable is now multiplied by 256 to determine the maximum number of concurrent asynchronous I/O read requests that can be completed by the Background Thread Pool. The default is therefore 4*256 = 1024 conccurrent asynchronous read requests. You may on rare occasions need to reduce this default on Linux systems running multiple MariaDB servers to avoid exceeding system limits, or increase if spending too much time waiting on I/O requests.
Command line: --innodb-read-io-threads=#
Scope: Global
innodb_read_onlyDescription: If set to 1 (0 is default), the server are read-only. For use in distributed applications, data warehouses or read-only media.
Command line: --innodb-read-only={0|1}
Scope: Global
innodb_read_only_compressedDescription: If set (the default before ), tables are read-only. This was intended to be the first step towards removing write support and deprecating the feature, but this plan has been abandoned.
Command line: --innodb-read-only-compressed, --skip-innodb-read-only-compressed
Scope: Global
innodb_recovery_statsDescription: If set to 1 (0 is default) and recovery is necessary on startup, the server will write detailed recovery statistics to the error log at the end of the recovery process. This Percona XtraDB variable has not been ported to XtraDB 5.6.
Command line: No
Scope: Global
innodb_recovery_update_relay_logDescription: If set to 1 (0 is default), the relay log info file are overwritten on crash recovery if the information differs from the InnoDB record. Should not be used if multiple storage engine types are being replicated. Previously named innodb_overwrite_relay_log_info. Removed in /XtraDB 5.6 and replaced by MySQL 5.6's relay-log-recovery
Command line: innodb-recovery-update-relay-log={0|1}
innodb_replication_delayDescription: Time in milliseconds for the replica server to delay the replication thread if is reached. Deprecated and ignored from .
Command line: --innodb-replication-delay=#
Scope: Global
Dynamic: Yes
innodb_rollback_on_timeoutDescription: InnoDB usually rolls back the last statement of a transaction that's been timed out (see ). If innodb_rollback_on_timeout is set to 1 (0 is default), InnoDB will roll back the entire transaction. Before , rolling back the entire transaction was the default behavior.
Command line: --innodb-rollback-on-timeout
Scope: Global
Dynamic: No
innodb_rollback_segmentsDescription: Specifies the number of rollback segments that XtraDB/InnoDB will use within a transaction (see ). Deprecated and replaced by in . Removed in as part of an InnoDB cleanup, as it makes sense to always create and use the maximum number of rollback segments. |
Command line: --innodb-rollback-segments=#
Scope: Global
innodb_safe_truncateDescription: Use a backup-safe implementation and crash-safe rename operations inside InnoDB. This is not compatible with hot backup tools other than . Users who need to use such tools may set this to OFF.
Command line: --innodb-safe-truncate={0|1}
Scope: Global
innodb_scrub_logDescription: Enable scrubbing. See . Deprecated and ignored from , as never really worked ( and ). If old log contents should be kept secret, then enabling or setting a smaller could help.
Command line: --innodb-scrub-log
Scope: Global
innodb_scrub_log_intervalDescription: Used with in 10.1.3 only - replaced in 10.1.4 by . scrubbing interval in milliseconds.
Command line: --innodb-scrub-log-interval=#
Scope: Global
Dynamic: Yes
innodb_scrub_log_speedDescription: scrubbing speed in bytes/sec. See . Deprecated and ignored from .
Command line: --innodb-scrub-log-speed=#
Scope: Global
Dynamic: Yes
innodb_sched_priority_cleanerDescription: Set a thread scheduling priority for cleaner and least-recently used (LRU) manager threads. The range from 0 to 39 corresponds in reverse order to Linux nice values of -20 to 19. So 0 is the lowest priority (Linux nice value 19) and 39 is the highest priority (Linux nice value -20). XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
innodb_show_locks_heldDescription: Specifies the number of locks held for each InnoDB transaction to be displayed in output. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-show-locks-held=#
Scope: Global
Dynamic: Yes
innodb_show_verbose_locksDescription: If set to 1, and is also ON, the traditional InnoDB behavior is followed and locked records are shown in output. If set to 0, the default, only high-level information about the lock is shown. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-show-verbose-locks=#
Scope: Global
innodb_simulate_comp_failuresDescription: Simulate compression failures. Used for testing robustness against random compression failures. XtraDB only.
Command line: None
Scope: Global
Dynamic: Yes
innodb_snapshot_isolationDescription: Use snapshot isolation (write-write conflict detection). If set, if an attempt to acquire a lock on a record that does not exist in the current read view is made, an error DB_RECORD_CHANGED (HA_ERR_RECORD_CHANGED, ER_CHECKREAD) are raised. This error are treated in the same way as a deadlock and the transaction are rolled back. When set, the default isolation level, arecome Snapshot Isolation. Prior to , the default is OFF for backwards compatibility.
Command line: --innodb-snapshot-isolation={0|1}
Scope: Global, Session
innodb_sort_buffer_sizeDescription: Size of the sort buffers used for sorting data when an InnoDB index is created, as well as the amount by which the temporary log file is extended during online DDL operations to record concurrent writes. The larger the setting, the fewer merge phases are required between buffers while sorting. When a or creates a new index, three buffers of this size are allocated, as well as pointers for the rows in the buffer.
Command line: --innodb-sort-buffer-size=#
Scope: Global
innodb_spin_wait_delayDescription: Maximum delay (not strictly corresponding to a time unit) between spin lock polls. Default changed from 6 to 4 in , as this was verified to give the best throughput by OLTP update index and read-write benchmarks on Intel Broadwell (2/20/40) and ARM (1/46/46).
Command line: --innodb-log-spin-wait-delay=#
Scope: Global
innodb_stats_auto_recalcDescription: If set to 1 (the default), persistent statistics are automatically recalculated when the table changes significantly (more than 10% of the rows). Affects tables created or altered with STATS_PERSISTENT=1 (see ), or when is enabled. determines how much data to sample when recalculating. See .
Command line: --innodb-stats-auto-recalc={0|1}
Scope: Global
innodb_stats_auto_updateDescription: If set to 0 (1 is default), index statistics will not be automatically calculated except when an is run, or the table is first opened. Replaced by in /XtraDB 5.6.
Scope: Global
Dynamic: Yes
innodb_stats_include_delete_markedDescription: Include delete marked records when calculating persistent statistics.
Scope: Global
Dynamic: Yes
Data Type: boolean
innodb_stats_methodDescription: Determines how NULLs are treated for InnoDB index statistics purposes.
nulls_equal: The default, all NULL index values are treated as a single group. This is usually fine, but if you have large numbers of NULLs the average group size is slanted higher, and the optimizer may miss using the index for ref accesses when it would be useful.
nulls_unequal: The opposite approach to nulls_equal is taken, with each NULL forming its own group of one. Conversely, the average group size is slanted lower, and the optimizer may use the index for ref accesses when not suitable.
innodb_stats_modified_counterDescription: The number of rows modified before we calculate new statistics. If set to 0, the default, current limits are used.
Command line: --innodb-stats-modified-counter=#
Scope: Global
Dynamic: Yes
innodb_stats_on_metadataDescription: If set to 1, the default, XtraDB/InnoDB updates statistics when accessing the INFORMATION_SCHEMA.TABLES or INFORMATION_SCHEMA.STATISTICS tables, and when running metadata statements such as or . If set to 0, statistics are not updated at those times, which can reduce the access time for large schemas, as well as make execution plans more stable.
Command line: --innodb-stats-on-metadata
Scope: Global
innodb_stats_persistentDescription: produces index statistics, and this setting determines whether they are stored on disk, or be required to be recalculated more frequently, such as when the server restarts. This information is stored for each table, and can be set with the STATS_PERSISTENT clause when creating or altering tables (see ). See .
Command line: --innodb-stats-persistent={0|1}
Scope: Global
innodb_stats_persistent_sample_pagesDescription: Number of index pages sampled when estimating cardinality and statistics for indexed columns. Increasing this value will increases index statistics accuracy, but use more I/O resources when running . See .
Command line: --innodb-stats-persistent-sample-pages=#
Scope: Global
Dynamic: Yes
innodb_stats_sample_pagesDescription: Gives control over the index distribution statistics by determining the number of index pages to sample. Higher values produce more disk I/O, but, especially for large tables, produce more accurate statistics and therefore make more effective use of the query optimizer. Lower values than the default are not recommended, as the statistics can be quite inaccurate.
If is enabled, then the exact number of pages configured by this system variable are sampled for statistics.
If is disabled, then the number of pages to sample for statistics is calculated using a logarithmic algorithm, so the exact number can change depending on the size of the table. This means that more samples may be used for larger tables.
innodb_stats_traditionalDescription: This system variable affects how the number of pages to sample for transient statistics is determined, in particular how is used.
If is enabled, then the exact number of pages configured by the system variable are sampled for statistics.
If is disabled, then the number of pages to sample for statistics is calculated using a logarithmic algorithm, so the exact number can change depending on the size of the table. This means that more samples may be used for larger tables.
innodb_stats_transient_sample_pagesDescription: Gives control over the index distribution statistics by determining the number of index pages to sample. Higher values produce more disk I/O, but, especially for large tables, produce more accurate statistics and therefore make more effective use of the query optimizer. Lower values than the default are not recommended, as the statistics can be quite inaccurate.
If is enabled, then the exact number of pages configured by this system variable are sampled for statistics.
If is disabled, then the number of pages to sample for statistics is calculated using a logarithmic algorithm, so the exact number can change depending on the size of the table. This means that more samples may be used for larger tables.
innodb_stats_update_need_lockDescription: Setting to 0 (1 is default) may help reduce contention of the &dict_operation_lock, but also disables the Data_free option in . This Percona XtraDB variable has not been ported to XtraDB 5.6.
Scope: Global
Dynamic: Yes
innodb_status_outputDescription: Enable output to the .
Command line: --innodb-status-output={0|1}
Scope: Global
Dynamic: Yes
innodb_status_output_locksDescription: Enable output to the and . Also requires to enable output to the error log.
Command line: --innodb-status-output-locks={0|1}
Scope: Global
Dynamic: Yes
innodb_strict_modeDescription: If set to 1 (the default), InnoDB will return errors instead of warnings in certain cases, similar to strict SQL mode. See for details.
Command line: --innodb-strict-mode={0|1}
Scope: Global, Session
innodb_support_xaDescription: If set to 1, the default, are supported. XA support ensures data is written to the in the same order to the actual database, which is critical for and disaster recovery, but comes at a small performance cost. If your database is set up to only permit one thread to change data (for example, on a replication replica with only the replication thread writing), it is safe to turn this option off. Removed in , XA transactions are always supported.
Command line: --innodb-support-xa
Scope: Global, Session
innodb_sync_array_sizeDescription: By default 1, can be increased to split internal thread co-ordinating, giving higher concurrency when there are many waiting threads.
Command line: --innodb-sync-array-size=#
Scope: Global
Dynamic: No
innodb_sync_spin_loopsDescription: The number of times a thread waits for an InnoDB mutex to be freed before the thread is suspended.
Command line: --innodb-sync-spin-loops=#
Scope: Global
Dynamic: Yes
innodb_table_locksDescription: If is set to 0 (1 is default), setting innodb_table_locks to 1, the default, will cause InnoDB to lock a table internally upon a .
Command line: --innodb-table-locks
Scope: Global, Session
innodb_thread_concurrencyDescription: Once this number of threads is reached (excluding threads waiting for locks), XtraDB/InnoDB will place new threads in a wait state in a first-in, first-out queue for execution, in order to limit the number of threads running concurrently. A setting of 0, the default, permits as many threads as necessary. A suggested setting is twice the number of CPU's plus the number of disks. Deprecated and ignored from .
Command line: --innodb-thread-concurrency=#
Scope: Global
innodb_thread_concurrency_timer_basedDescription: If set to 1, thread concurrency are handled in a lock-free timer-based manner rather than the default mutex-based method. Depends on atomic op builtins being available. This Percona XtraDB variable has not been ported to XtraDB 5.6.
Command line: innodb-thread-concurrency-timer-based={0|1}
Scope: Global
innodb_thread_sleep_delayDescription: Time in microseconds that InnoDB threads sleep before joining the queue. Setting to 0 disables sleep. Deprecated and ignored from
Command line: --innodb-thread-sleep-delay=#
Scope: Global
innodb_temp_data_file_pathDescription: Path where to store data for temporary tables. Argument is filename:size followed by options separated by ':' Multiple paths can be given separated by ';' A file size is specified (with K for kilobytes, M for megabytes and G for gigabytes). Also whether or not to autoextend the data file, max size and whether or not to on startup may also be specified.
Command line: --innodb-temp-data-file-path=path
innodb_tmpdirDescription: Allows an alternate location to be set for temporary non-tablespace files. If not set (the default), files are created in the usual location.
Alternate location must be outside of datadir
Command line: --innodb-tmpdir=path
Scope: Global
innodb_track_changed_pagesDescription: For faster incremental backup with , XtraDB tracks pages with changes written to them according to the and writes the information to special changed page bitmap files. This read-only variable is used for controlling this feature. See also and . XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-track-changed-pages={0|1}
Scope: Global
innodb_track_redo_log_nowDescription: Available on debug builds only. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-track-redo-log-now={0|1}
Scope: Global
Dynamic: Yes
innodb_truncate_temporary_tablespace_nowDescription: Set to ON to shrink the temporary tablespace.
Command line: innodb-truncate-temporary-tablespace-now={0|1}
Scope: Global
Dynamic: Yes
innodb_undo_directoryDescription: Path to the directory (relative or absolute) that InnoDB uses to create separate tablespaces for the . . (the default value before 10.2.2) leaves the undo logs in the same directory as the other log files. From , the default value is NULL, and if no path is specified, undo tablespaces are created in the directory defined by . Use together with and . Undo logs are most usefully placed on a separate storage device.
Command line: --innodb-undo-directory=name
Scope: Global
innodb_undo_log_truncateDescription: When enabled, that are larger than are marked for truncation. See also . Enabling this setting may cause stalls during heavy write workloads.
Command line: --innodb-undo-log-truncate[={0|1}]
Scope: Global
Dynamic: Yes
innodb_undo_logsDescription: Specifies the number of rollback segments that XtraDB/InnoDB will use within a transaction (or the number of active ). By default set to the maximum, 128, it can be reduced to avoid allocating unneeded rollback segments. See the status variable for the number of undo logs available. See also and . Replaced in . The contains information about the XtraDB rollback segments. Deprecated and ignored in , as it always makes sense to use the maximum number of rollback segments.
Command line: --innodb-undo-logs=#
innodb_undo_tablespacesDescription: Number of tablespaces files used for dividing up the . Zero (the default before ) means that undo logs are all part of the system tablespace, which contains one undo tablespace more than the innodb_undo_tablespaces setting. A value of 1 is reset to 0 as 2 or more are needed for separate tablespaces. When the undo logs can grow large, splitting them over multiple tablespaces will reduce the size of any single tablespace. Until , must be set before InnoDB is initialized, or else MariaDB will fail to start, with an error saying that InnoDB did not find the expected number of undo tablespaces. The files are created in the directory specified by , and are named undoN, N being an integer. The default size of an undo tablespace is 10MB.From , multiple undo tablespaces are enabled by default, and the default is changed to 3 so that the space occupied by possible bursts of undo log records can be reclaimed after is set. Before , must have a non-zero setting for innodb_undo_tablespaces to take effect.
innodb_use_atomic_writesDescription: Implement atomic writes on supported SSD devices. See for other variables affected when this is set.
Command line: innodb-use-atomic-writes={0|1}
Scope: Global
Dynamic: No
innodb_use_fallocateDescription: Preallocate files fast, using operating system functionality. On POSIX systems, posix_fallocate system call is used.
Automatically set to 1 when is set - see .
See for more information.
innodb_use_global_flush_log_at_trx_commitDescription: Determines whether a user can set the variable . If set to 1, a user cannot reset the value with a SET command, while if set to 1, a user can reset the value of innodb_flush_log_at_trx_commit. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-use-global-flush-log-at-trx_commit={0|1}
innodb_use_mtflushDescription: Whether to enable Multi-Threaded Flush operations. For more information, see Fusion.
InnoDB's multi-thread flush feature was deprecated in and removed from . In later versions of MariaDB, use system variable instead.
See for more information.
Command line:
innodb_use_native_aioDescription: For Linux systems only, specified whether to use Linux's asynchronous I/O subsystem. Set to ON by default, it may be changed to 0 at startup if InnoDB detects a problem, or from /, if a 5.11 - 5.15 Linux kernel is detected, to avoid an io-uring bug/incompatibility (). MariaDB-10.6.6/MariaDB-10.7.2 and later also consider 5.15.3+ as a fixed kernel and default to ON. To really benefit from the setting, the files should be opened in O_DIRECT mode (, default from ), to bypass the file system cache. In this way, the reads and writes can be submitted with DMA, using the InnoDB buffer pool directly, and no processor cycles need to be used for copying data.
Command line: --innodb-use-native-aio={0|1}
innodb_use_purge_threadDescription: Usually with InnoDB, data changed by a transaction is written to an undo space to permit read consistency, and freed when the transaction is complete. Many, or large, transactions, can cause the main tablespace to grow dramatically, reducing performance. This option, introduced in XtraDB 5.1 and removed for 5.5, allows multiple threads to perform the purging, resulting in slower, but much more stable performance.
Command line: --innodb-use-purge-thread=#
Scope: Global
innodb_use_stacktraceDescription: If set to ON (OFF is default), a signal handler for SIGUSR2 is installed when the InnoDB server starts. When a long semaphore wait is detected at sync/sync0array.c, a SIGUSR2 signal is sent to the waiting thread and thread that has acquired the RW-latch. For both threads a full stacktrace is produced as well as if possible. XtraDB only. Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: --innodb-use-stacktrace={0|1}
Scope: Global
innodb_use_sys_mallocDescription: If set the 1, the default, XtraDB/InnoDB will use the operating system's memory allocator. If set to 0 it will use its own. Deprecated in and removed in along with InnoDB's internal memory allocator.
Command line: --innodb-use-sys-malloc={0|1}
Scope: Global
innodb_use_sys_stats_tableDescription: If set to 1 (0 is default), XtraDB will use the SYS_STATS system table for extra table index statistics. When a table is opened for the first time, statistics will then be loaded from SYS_STATS instead of sampling the index pages. Statistics are designed to be maintained only by running an . Replaced by MySQL 5.6's Persistent Optimizer Statistics.
Command line: innodb-use-sys-stats-table={0|1}
Scope: Global
innodb_use_trimDescription: Use trim to free up space of compressed blocks.
See for more information.
Command line: --innodb-use-trim={0|1}
Scope: Global
innodb_versionDescription: InnoDB version number. From , as the InnoDB implementation in MariaDB has diverged from MySQL, the MariaDB version is instead reported. For example, the InnoDB version reported in (which is based on MySQL 5.6) included encryption and variable-size page compression before MySQL 5.7 introduced them. (based on MySQL 5.7) introduced persistent AUTO_INCREMENT () in a GA release before MySQL 8.0. (based on MySQL 5.7) introduced instant ADD COLUMN () before MySQL.
Scope: Global
Dynamic: No
innodb_write_io_threadsDescription: Prior to , this was simply the number of I/O threads for InnoDB writes. From , asynchronous I/O functionality in the InnoDB Background Thread Pool replaces the old InnoDB I/O Threads. This variable is now multiplied by 256 to determine the maximum number of concurrent asynchronous I/O write requests that can be completed by the Background Thread Pool. The default is therefore 4*256 = 1024 conccurrent asynchronous write requests. You may on rare occasions need to reduce this default on Linux systems running multiple MariaDB servers to avoid exceeding system limits, or increase if spending too much time waiting on I/O requests.
Command line: --innodb-write-io-threads=#
Scope: Global
This page is licensed: CC BY-SA / Gnu FDL
Dynamic: No
Data Type: boolean
Default Value: OFF
estimate The default, and independent of innodb_io_capacity. If the oldest modified age exceeds 1/2 of the maximum age capacity, blocks are flushed every second at a rate determined by the number of modified blocks, LSN progress speed and the average age of all modified blocks.keep_average Attempts to keep the I/O rate constant by using a shorter loop cycle of one tenth of a second. Designed for SSD cards.
Command line: --innodb-adaptive-checkpoint=#
Scope: Global
Dynamic: Yes
Data Type: string
Default Value: estimate
Valid Values: none or 0, reflex or 1, estimate or 2, keep_average or 3
Removed: XtraDB 5.5 - replaced with innodb_adaptive_flushing_method
Dynamic: Yes
Data Type: boolean
Default Value: ON
Data Type: double
Default Value: 10.000000
Range: 0 to 70
Command line: innodb-adaptive-flushing-method=value
Scope: Global
Dynamic: Yes
Data Type: enumeration
Default Value: estimate
Valid Values: native or 0, estimate or 1, keep_average or 2
Removed: - replaced with InnoDB flushing method from MySQL 5.6
Dynamic: Yes
Data Type: boolean
Default Value: OFF (>= ), ON (<= )
Data Type: numeric
Default Value: 1
Range: 1 to 64
Data Type: numeric
Default Value: 8
Range: 1 to 512
Data Type: numeric
Default Value:
0 (>= )
150000 (<= )
Range: 0 to 1000000
Introduced:
Deprecated:
Removed: MariaDB 10.6.0
Data Type: numeric
Default Value: 8388608
Range: 2097152 to 4294967295
Deprecated:
Removed:
Default Value: ON
Introduced: MariaDB 10.11.9, , , MariaDB 11.4.3, ,
Data Type: numeric
Default Value: 5
Range: 1 to 1073741824
Introduced:
Removed:
Data Type: boolean
Default Value: OFF
Introduced:
Removed:
Data Type: boolean
Default Value: OFF
Introduced:
Removed:
Data Type: boolean
Default Value: OFF
Introduced:
Removed:
Data Type: numeric
Default Value: 0
Introduced:
Removed:
Data Type: numeric
Default Value: 64 (from ) 8 (before ),
Range: 1 to 1000
1 is the consecutive lock mode.2 is the interleaved lock mode.
In order to use Galera Cluster, the lock mode needs to be set to 2.
See AUTO_INCREMENT Handling in InnoDB: AUTO_INCREMENT Lock Modes for more information.
Command line: --innodb-autoinc-lock-mode=#
Scope: Global
Dynamic: No
Data Type: numeric
Default Value: 1
Range: 0 to 2
Data Type: numeric
Default Value: 3600
Range: 1 to 4294967295
Deprecated:
Removed: MariaDB 10.6.0
Data Type: boolean
Default Value: 0
Deprecated:
Removed: MariaDB 10.6.0
Data Type: numeric
Default Value: 604800
Range: 1 to 4294967295
Deprecated:
Removed: MariaDB 10.6.0
Data Type: boolean
Default Value: 0
Deprecated:
Removed: MariaDB 10.6.0
Dynamic: No
Data Type: boolean
Default Value: OFF
Removed:
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range: 0 to 100
Data Type: numeric
Default Value:
autosize (0), resulting in innodb_buffer_pool_size/64, if large_pages round down to multiple of largest page size, with 1MiB minimum (from )
134217728 (until )
Range:
0, as autosize, and then 1048576 to 18446744073709551615 (from )
1048576 to innodb_buffer_pool_size/innodb_buffer_pool_instances (until )
Block size: 1048576
Deprecated and ignored from MariaDB 10.11.12, MariaDB 11.4.6, MariaDB 11.8.2
Data Type: boolean
Default Value: ON
Data Type: boolean
Default Value: OFF
Introduced:
Data Type: boolean
Default Value:
25
Range: 1 to 100
Data Type: string
Default Value: ""
Valid Values: "" or "uncompressed"
Data Type: string
Default Value: ib_buffer_pool
Introduced:
Scope: Global
Dynamic: No
Data Type: numeric
Default Value: >= : 8, 1 (>= if innodb_buffer_pool_size < 1GB), or dependent on innodb_buffer_pool_size (Windows 32-bit)
Deprecated:
Removed: MariaDB 10.6.0
Data Type: boolean
Default Value: OFF
Data Type: boolean
Default Value: ON
Data Type: boolean
Default Value: OFF
Data Type: numeric
Default Value: 9223372036854775807
Range: 1 to 9223372036854775807
Dynamic: No
Data Type: boolean
Default Value: OFF
Deprecated:
Removed:
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range - 32 bit: 0 to 4294967295
Range - 64 bit: 0 to 18446744073709547520
Removed: - replaced by innodb_buffer_pool_load_at_startup
Data Type: boolean
Default Value: ON
Removed:
Data Type: boolean
Default Value: 0
Removed:
Data Type: numeric
Default Value: 134217728 (128MiB)
Range:
Minimum: 5242880 (5MiB ) for InnoDB Page Size <= 16k otherwise 25165824 (24MiB) for InnoDB Page Size > 16k (for versions less than next line)
Minimum: 2MiB InnoDB Page Size = 4k, 3MiB InnoDB Page Size = 8k, 5MiB = 16k, 10MiB = 32k, 20MiB = 64k, (>= , >= , >= , >= , >= , >= )
Minimum: 1GiB for > 1 (<= )
Maximum: 9223372036854775807 (8192PB) (all versions)
Block size: 1048576
Dynamic: Yes
Data Type: numeric
Default Value: 134217728 (128MiB)
Range: 0 to 18446744073701163008
Block size: 8388608 (8 MB on 64-bit systems)
Introduced: MariaDB 10.11.12, MariaDB 11.4.6, MariaDB 11.8.2
Data Type: numeric
Default Value: specified by the initial value of innodb_buffer_pool_size, rounded up to the block size of that variable. See the section about buffer pool changes in MariaDB 10.11.12, 11.4.6, and 11.8.2.
Range: 0 to 18446744073701163008
Block size: 8388608 (8 MB on 64-bit systems)
Introduced: MariaDB 10.11.12, MariaDB 11.4.6, MariaDB 11.8.2
Default Value: OFF
Introduced: , ,
Data Type: numeric
Default Value: 25
Range: 0 to 50
Introduced:
Deprecated:
Removed:
Data Type: enumeration (>= ), string (<= )
Default Value:
= , MariaDB 10.6.7, , :
none
<= , MariaDB 10.6.6, , :all
Valid Values: inserts, none, deletes, purges, changes, all
Deprecated:
Removed:
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range: 0 to 2
Data Type: numeric
Default Value: 0
Range: 0 upwards
Removed: - replaced with InnoDB flushing method from MySQL 5.6.
full_crc32 and strict_full_crc32: From . Permits encryption to be supported over a SPATIAL INDEX, which crc32 does not support. Newly-created data files will carry a flag that indicates that all pages of the file will use a full CRC-32C checksum over the entire page contents (excluding the bytes where the checksum is stored, at the very end of the page). Such files will always use that checksum, no matter what parameter innodb_checksum_algorithm is assigned to. Even if innodb_checksum_algorithm is modified later, the same checksum will continue to be used. A special flag are set in the FSP_SPACE_FLAGS in the first data page to indicate the new format of checksum and encryption/page_compressed. ROW_FORMAT=COMPRESSED tables will only use the old format.
These tables do not support new features, such as larger innodb_page_size or instant ADD/DROP COLUMN. Also cleans up the MariaDB tablespace flags - flags are reserved to store the page_compressed compression algorithm, and to store the compressed payload length, so that checksum can be computed over the compressed (and possibly encrypted) stream and can be validated without decrypting or decompressing the page. In the full_crc32 format, there no longer are separate before-encryption and after-encryption checksums for pages. The single checksum is computed on the page contents that is written to the file.See MDEV-12026 for details.
none: Writes a constant rather than calculate a checksum. Deprecated in , , and removed in MariaDB 10.6 as was mostly used to disable the original, slow, page checksum for benchmarking purposes.
strict_crc32, strict_innodb and strict_none: The options are the same as the regular options, but InnoDB will halt if it comes across a mix of checksum values. These are faster, as both new and old checksum values are not required, but can only be used when setting up tablespaces for the first time.
Command line: --innodb-checksum-algorithm=#
Scope: Global
Dynamic: Yes
Data Type: enumeration
Default Value:
full_crc32 (>= )
crc32 (>= to <= )
innodb (<= )
Valid Values:
= MariaDB 10.6.0:
crc32,full_crc32,strict_crc32,strict_full_crc32
, >= : innodb, crc32, full_crc32, none, strict_innodb, strict_crc32, strict_none, strict_full_crc32
<= : innodb, crc32, none, strict_innodb, strict_crc32, strict_none
--skip-innodb-checksumsScope: Global
Dynamic: No
Data Type: boolean
Default Value: ON
Deprecated:
Removed:
Dynamic: Yes
Data Type: enum
Default Value:
deprecated
Valid Values:
deprecated, high_checkpoint, legacy
Deprecated:
Removed:
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Introduced:
Data Type: numeric
Default Value: 0
Range: 0 to 1000
Deprecated:
Removed: MariaDB 10.6.0
lz4: Pages are compressed using the lz4 compression algorithm.lzo: Pages are compressed using the lzo compression algorithm.
lzma: Pages are compressed using the lzma compression algorithm.
bzip2: Pages are compressed using the bzip2 compression algorithm.
snappy: Pages are compressed using the snappy algorithm.
On many distributions, MariaDB may not support all page compression algorithms by default. From , libraries can be installed as a plugin. See Compression Plugins.
See InnoDB Page Compression: Configuring the InnoDB Page Compression Algorithm for more information.
Command line: --innodb-compression-algorithm=value
Scope: Global
Dynamic: Yes
Data Type: enum
Default Value: zlib
Valid Values:none, zlib, lz4, lzo, lzma, bzip2 or snappy
--innodb-compression-default={0|1}Scope: Global, Session
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 5
Range: 0 to 100
Introduced:
19See InnoDB Page Compression: Configuring the Default Compression Level for more information.
Command line: --innodb-compression-level=#
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 6
Range: 1 to 9
Introduced:
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 50
Range: 0 to 75
Introduced:
Data Type: numeric
Default Value:
0 (>= )
5000 (<= )
Range: 1 to 18446744073709551615
Deprecated:
Removed: MariaDB 10.6.0
If set to salvage, read access is permitted, but corrupted pages are ignored. innodb_file_per_table must be enabled for this option. Previously named innodb_pass_corrupt_table.
Added as a deprecated and ignored option in (which uses InnoDB as default instead of XtraDB) to allow for easier upgrades.
Command line: innodb-corrupt-table-action=value
Scope: Global
Dynamic: Yes
Data Type: enumeration
Default Value:
assert (<= )
deprecated (<= )
Valid Values:
deprecated, assert, warn, salvage
Deprecated:
Removed:
Scope: Global
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Introduced:
Dynamic: No
Data Type: numeric
Default Value: ibdata1:12M:autoextend (from ), ibdata1:10M:autoextend (before )
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Introduced:
Data Type: directory name
Default Value: The MariaDB data directory
Data Type: boolean
Default Value: 1
full: Default. Report transactions, waiting locks and blocking locks.Command line: --innodb-deadlock-report=val
Scope: Global
Dynamic: Yes
Data Type: enum
Default Value: full
Valid Values: off, basic, full
Introduced: MariaDB 10.6.0
Dynamic: Yes
Data Type: numeric
Default Value: 1
Range: 1 to 255
Introduced:
Removed:
Dynamic: Yes
Data Type: numeric
Default Value: 1
Range: 1 to 4294967295
Dynamic: Yes
Data Type: enum
Default Value: dynamic
Valid Values: redundant, compact or dynamic
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Deprecated:
Removed:
Data Type: double
Default Value: 0.9
Range: 0.7 to 1
Deprecated:
Removed:
Data Type: numeric
Default Value: 20
Range: 1 to 100
Deprecated:
Removed:
Data Type: integer
Default Value: 40
Range: 1 to 1000
Deprecated:
Removed:
Data Type: numeric
Default Value: 7
Range: 2 to 32
Deprecated:
Removed:
Data Type: numeric
Default Value: 0
Range: 0 to 4294967295
Deprecated:
Removed:
Dynamic: Yes
Data Type: numeric
Default Value: 0
Default Value - 32 bit: 2147483648
Default Value - 64 bit: 9223372036854775807
Removed: - replaced by MySQL 5.6's table_definition_cache implementation.
Data Type: boolean
Default Value: OFF
booleanDefault Value: OFF
Removed: , , , MariaDB 10.6.8,
The setting innodb_doublewrite=fast could be safe when the doublewrite buffer (the first file of the system tablespace) and the data files reside in the same file system.
Command line: --innodb-doublewrite{=val}, --skip-innodb-doublewrite
Scope: Global
Dynamic: Yes
Data Type: enum
Default Value: ON
Valid Values: OFF, ON, fast
Description: If set to 1, the default, to improve fault tolerance InnoDB first stores data to a doublewrite buffer before writing it to data file. Disabling will provide a marginal performance improvement.
Command line: --innodb-doublewrite, --skip-innodb-doublewrite
Scope: Global
Dynamic:No
Data Type: boolean
Default Value: ON
Data Type: filename
Default Value: NULL
Removed:
Scope: Global
Dynamic: Yes
Data Type: enum
Default Value:
deprecated
Valid Values:
deprecated, backoff, legacy
Deprecated:
Removed:
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range: 0 to 1
Removed: Not needed after XtraDB 1.0.5
Dynamic: No
Data Type: boolean
Default Value: OFF
FORCE - Enables table encryption for all new and existing tables that have the ENCRYPTED table option set to DEFAULT, and doesn't allow unencrypted tables to be created (CREATE TABLE ... ENCRYPTED=NO will fail).
See Data-at-Rest Encryption and Enabling InnoDB Encryption: Enabling Encryption for Automatically Encrypted Tablespaces for more information.
Command line: --innodb-encrypt-tables={0|1}
Scope: Global
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Valid Values: ON, OFF, FORCE
Dynamic: No
Data Type: boolean
Default Value: OFF
Valid Values: ON, OFF
Introduced: , ,
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 1
Range: 0 to 4294967295
Dynamic: Yes
Data Type: numeric
Default Value: 100
Range: 0 to 4294967295
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range:
0 to 4294967295 (<= , , , , )
0 to 255 (>= , , , , )
Data Type: numeric
Default Value: 0
Range: 0 to 126
Removed: XtraDB 5.5 - replaced by innodb_rollback_segments
Dynamic: No
Data Type: boolean
Default Value: OFF
Removed: XtraDB 5.5
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Deprecated:
Removed:
Scope: Global
Dynamic: No
Data Type: boolean
Default Value: OFF
Removed: /XtraDB 5.6 - replaced with innodb_checksum_algorithm
2, the InnoDB redo log is flushed and a cold shutdown takes place, similar to a crash. The resulting startup then performs crash recovery. Extremely fast, in cases of emergency, but risks corruption. Not suitable for upgrades between major versions!
3 (from ) - active transactions will not be rolled back, but all changed pages are written to data files. The active transactions are rolled back by a background thread on a subsequent startup. The fastest option that will not involve InnoDB redo log apply on subsequent startup. See MDEV-15832.
Command line: --innodb-fast-shutdown[=#]
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 1
Range: 0 to 3 (>= ), 0 to 2 (<= )
Data Type: numeric
Default Value: 600
Range: 1 to 4294967295
Dynamic: Yes
Data Type: string
Default Value:
Barracuda
Valid Values: Antelope, Barracuda
Deprecated:
Removed:
Re-introduced: (for compatibility purposes)
Removed: MariaDB 10.6.0
Dynamic: No
Data Type: boolean
Default Value: ON
Deprecated:
Removed:
Data Type: string
Default Value: Antelope
Valid Values: Antelope, Barracuda
Deprecated:
Removed:
Scope: Global
Dynamic: Yes
Data Type: boolean
Default Value: ON
Deprecated:
Data Type: numeric
Default Value: 100
Range: 10 to 100
Default Value: 1
Range: 0 to 2700
2 The log buffer is written to the InnoDB redo log after each commit, but flushing takes place every innodb_flush_log_at_timeout seconds (by default once a second). Performance is slightly better, but a OS or power outage can cause the last second's transactions to be lost.
3 Emulates group commit (3 syncs per group commit). See Binlog group commit and innodb_flush_log_at_trx_commit. This option has not been working correctly since 10.2 and may be removed in future, see 1873
Command line: --innodb-flush-log-at-trx-commit[=#]
Scope: Global
Dynamic: Yes
Data Type: enumeration
Default Value: 1
Valid Values: 0, 1, 2 or 3
fsync - Default on Unix until . Can be specified directly, but if the variable is unset on Unix, fsync() are used by default.
O_DIRECT_NO_FSYNC - introduced in . Uses O_DIRECT during flushing I/O, but skips fsync() afterwards. Not suitable for XFS filesystems. Generally not recommended over O_DIRECT, as does not get the benefit of innodb_use_native_aio=ON.
ALL_O_DIRECT - introduced in and available with XtraDB only. Uses O_DIRECT for opening both data and logs and fsync() to flush data but not logs. Use with large InnoDB files only, otherwise may cause a performance degradation. Set innodb_log_block_size to 4096 on ext4 filesystems. This is the default log block size on ext4 and will avoid unaligned AIO/DIO warnings.
unbuffered - Windows-only default
async_unbuffered - Windows-only, alias for unbuffered
normal - Windows-only, alias for fsync
littlesync - for internal testing only
nosync - for internal testing only
Deprecated in and replaced by four boolean dynamic variables that can be changed while the server is running: innodb_log_file_buffering (disable O_DIRECT, added by MDEV-28766 in 10.8.4, 10.9.2), innodb_data_file_buffering (disable O_DIRECT on data files), innodb_log_file_write_through (enable O_DSYNC on the log), innodb_data_file_write_through (enable O_DSYNC on persistent data files) From , if set to one of the following values, then the values of the four boolean flags are set as follows:
O_DSYNC: innodb_log_file_write_through=ON, innodb_data_file_write_through=ON,innodb_data_file_buffering=OFF, and (if supported) innodb_log_file_buffering=OFF.
fsync, littlesync, nosync, or (Microsoft Windows specific) normal: , , and .
Command line: --innodb-flush-method=name
Scope: Global
Dynamic: No
Data Type: enumeration (>= ), string (<= )
Default Value:
O_DIRECT (Unix, >= MariaDB 10.6.0)
fsync (Unix, >= , <= )
Not set (<= )
Valid Values:
Unix: fsync, O_DSYNC, littlesync, nosync. O_DIRECT, O_DIRECT_NO_FSYNC
Windows: unbuffered, async_unbuffered, normal
Deprecated:
Scope: Global
Dynamic: Yes
Data Type: enumeration
Default Value: area
Valid Values: none or 0, area or 1, cont or 2
Removed: /XtraDB 5.6 - replaced by innodb_flush_neighbors
0: No other dirty pages are flushed.2: Flushes dirty pages in the same extent from the buffer pool.
Command line: --innodb-flush-neighbors=#
Scope: Global
Dynamic: Yes
Data Type: enumeration
Default Value: 1
Valid Values: 0, 1, 2
Data Type: boolean
Default Value: ON
Data Type: numeric
Default Value: 30
Range: 1 to 1000
Scope: Global
Dynamic: No
Data Type: boolean
Default Value: OFF
Removed: MariaDB 10.6.6
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Data Type: enumeration
Default Value: 0
Range: 0 to 6
sync_preflushCommand line: innodb-foreground-preflush=value
Scope: Global
Dynamic: Yes
Data Type: enum
Default Value:
deprecated
Valid Values:
deprecated, exponential_backoff, sync_preflush
Deprecated:
Removed:
Dynamic: Yes
Data Type: string
Data Type: numeric
Default Value: 8000000
Data Type: boolean
Default Value: OFF
Dynamic: Yes
Data Type: boolean
Default Value: ON
Data Type: numeric
Default Value: 84
Range: 10 to 84
Data Type: numeric
Default Value: 3
Range: 1 to 16
Data Type: numeric
Default Value: 2000
Range: 1000 to 10000
Data Type: numeric
Default Value: 2000000000
Range: 1000000 to 18446744073709551615
Data Type: string
Default Value: Empty
Data Type: numeric
Default Value: 2
Range: 1 to 32
Data Type: numeric
Default Value: 640000000
Range: 32000000 to 1600000000
Introduced:
Data Type: string
Default Value: Empty
Dynamic: Yes
Data Type: numeric
Default Value: 100
Range: 100 to 999999999
Removed:
Dynamic: Yes
Data Type: numeric
Default Value: 1
Range: 0 to 1
Removed:
Dynamic: No
Data Type: numeric
Default Value: 1/2 the size of the InnoDB buffer pool
Range: 0 to 1/2 the size of the InnoDB buffer pool
Removed:
Data Type: numeric
Default Value: 100
Range: 0 to 100
Deprecated: , ,
Removed:
Data Type: boolean
Default Value: OFF
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range: 0 to 1
Removed:
This variable has been introduced as a result, with the following values:
never (0): Do not allow instant add/drop/reorder,
to maintain format compatibility with MariaDB 10.x and MySQL 5.x.
If the table (or partition) is not in the canonical format, then
any ALTER TABLE (even one that does not involve instant column
operations) will force a table rebuild.
add_last (1, default in 10.3): Store a hidden metadata record that
allows columns to be appended to the table instantly (MDEV-11369).
In 10.4 or later, if the table (or partition) is not in this format,
then any ALTER TABLE (even one that does not involve column changes)
will force a table rebuild.
add_drop_reorder (2, default): From only. Like 'add_last', but allow the
metadata record to store a column map, to support instant
add/drop/reorder of columns.
Command line: --innodb-instant-alter-column-allowed=value
Scope: Global
Dynamic: Yes
Data Type: enum
Valid Values:
<= : never, add_last
= :
never,add_last,add_drop_reorder
Default Value:
<= : add_last
= :
add_drop_reorder
Introduced: , ,
Data Type: boolean
Default Value: OFF
Deprecated: (treated as if OFF)
Removed:
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 200
Range: 100 to 18446744073709551615 (264-1)
Data Type: numeric
Default Value: 2000 or twice innodb_io_capacity, whichever is higher.
Range : 100 to 18446744073709551615 (264-1)
numericDefault Value: 0
Range: 0 to 9223372036854775807
Deprecated:
Removed:
Command line: --innodb-large-prefix
Scope: Global
Dynamic: Yes
Data Type: boolean
Default Value:
ON
Deprecated:
Removed:
Re-introduced: (for compatibility purposes)
Removed: MariaDB 10.6.0
Dynamic: Yes
Data Type: boolean
Default Value: 0
Deprecated: XtraDB 5.5.30-30.2
Removed:
Command line: --innodb-lock-schedule-algorithm=#
Scope: Global
Dynamic: No (>= , ), Yes (<= , )
Data Type: enum
Valid Values: FCFS, VATS
Default Value: FCFS (, ), VATS (), FCFS ()
Deprecated: , , ,
Removed: MariaDB 10.6.0
Scope: Global, Session
Dynamic: Yes
Data Type: INT UNSIGNED (>= MariaDB 10.6.3), BIGINT UNSIGNED (<= MariaDB 10.6.2)
Default Value: 50
Range:
0 to 100000000 (>= MariaDB 10.6.3)
0 to 1073741824 (>= to <= MariaDB 10.6.2)
Dynamic: Yes
Data Type: boolean
Default Value: ON
Deprecated:
Removed:
Dynamic: No
Data Type: boolean
Default Value: OFF
Deprecated:
Removed:
Data Type: string
Default Value: ./
Deprecated:
Removed:
Data Type: numeric
Default Value: 0
Deprecated:
Removed:
Data Type: boolean
Default Value: OFF
Deprecated:
Removed:
Scope: Global
Dynamic: No
Data Type: numeric
Default Value: 512
Deprecated:
Removed:
Data Type: numeric
Default Value: 16777216 (16MB)
Range: 262144 to 2147479552 (256KB to 2GB - 4K) (>= MariaDB 10.11.8)
Range: 262144 to 18446744073709551615 (<= MariaDB 10.11.7) - limit to the above maximum because this is an operating system limit.
Block size: 4096
Data Type: boolean
Default Value: OFF
Introduced: MariaDB 10.11.12, MariaDB 11.4.6, MariaDB 11.8.2
crc32 - CRC32© is used for log block checksums, which also permits recent CPUs to use hardware acceleration (on SSE4.2 x86 machines and Power8 or later) for the checksums.
strict_* - Whether or not to accept checksums from other algorithms. If strict mode is used, checksums blocks are considered corrupt if they don't match the specified algorithm. Normally they are considered corrupt only if no other algorithm matches.
Command line: innodb-log-checksum-algorithm=value
Scope: Global
Dynamic: Yes
Data Type: enum
Default Value:
deprecated (>= )
innodb (<= )
Valid Values:
deprecated, innodb, none, crc32, strict_none, strict_innodb, strict_crc32 (>= )
innodb, none, crc32, strict_none, strict_innodb, strict_crc32 (<= )
Deprecated:
Removed:
Dynamic: Yes
Data Type: boolean
Default Value: ON
Deprecated:
Removed: MariaDB 10.6.0
Data Type: boolean
Default Value:
ON
Deprecated:
Removed: MariaDB 10.6.0
Scope: Global
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Introduced: MariaDB 10.8.4, MariaDB 10.9.2
Dynamic: No
Data Type: boolean
Default Value: ON (Linux, FreeBSD), OFF (Other platforms)
Introduced: MariaDB 10.11.10, , MariaDB 11.4.4, ,
Dynamic: Yes (>= ), No (<= )
Data Type: numeric
Default Value: 100663296 (96MB) (>= ), 50331648 (48MB) (<= )
Range:
= :
4194304to512GB(4MB to 512GB)
<= : 1048576 to 512GB (1MB to 512GB)
Block size: 4096
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Introduced:
Data Type: numeric
Default Value: 1 (>= ), 2 (<= )
Range: 1 to 100 (>= )
Deprecated:
Removed: MariaDB 10.6.0
Data Type: directory name
Data Type: boolean
Default Value:
OFF (>= , , , )
ON (<= , , , )
Introduced: ,
Deprecated: , , ,
Removed: MariaDB 10.6.0
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range: 0 to 6000
Introduced: MariaDB 10.11.8, , , , MariaDB 11.4.2,
Data Type: numeric
Default Value: 512 (>= MariaDB 10.11.9), 8192 (<= )
Range:
512 to 4096 (>= MariaDB 10.11.9)
512 to innodb_page_size (<= )
Removed:
Re-introduced: MariaDB 10.11.9, , , MariaDB 11.4.3,
Data Type: numeric
Default Value:
0 (>=MariaDB 10.6.20, MariaDB 10.11.10, , MariaDB 11.4.4. , )
32 (<= MariaDB 10.6.19, MariaDB 10.11.9, , MariaDB 11.4.3)
Range: 1 to 18446744073709551615
Introduced:
Deprecated: MariaDB 10.6.20, MariaDB 10.11.10, and MariaDB 11.4.4. ,
Dynamic: Yes
Data Type: numeric
Default Value:
1536 (>= )
1024 (<= )
Range - 32bit: 100 to 2^32-1
Range - 64bit: 100 to 2^64-1
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 4096 (4KB)
Range: 4096 (4KB) to 18446744073709551615 (16EB)
Deprecated:
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 1000000
Range: 0 to 18446744073709551615
Deprecated:
Dynamic: Yes
Data Type: numeric
Default Value:
90.000000 (>= )
75.000000 (<= )
Range: 0 to 99.999
Dynamic: Yes
Data Type: numeric
Default Value:
0 (>= )
0.001 (<= )
Range: 0 to 99.999
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range: 0 to 4294967295
Data Type: numeric
Default Value: 0
Data Type: numeric
Default Value: 4294967295
Range: 0 to 4294967295
Introduced: , , ,
Data Type: numeric
Default Value:
10485760
Range: 10485760 to 18446744073709551615
Data Type: numeric
Default Value: 1048576 (1M)
Range: 1048576 (1M) to 1073741824 (1G)
Removed: - replaced by innodb_sort_buffer_size
--innodb-mtflush-threads=#Scope: Global
Dynamic: No
Data Type: numeric
Default Value: 8
Range: 1 to 64
Deprecated:
Removed:
Data Type: string
Data Type: string
Data Type: string
Data Type: string
Data Type: boolean
Default Value: OFF
Removed: , ,
Data Type: numeric
Default Value: 37
Range: 5 to 95
Data Type: numeric
Default Value: 1000
Range: 0 to 2^32-1
Dynamic: Yes
Data Type: numeric
Default Value: 134217728
Range: 65536 to 2^64-1
Dynamic: No
Data Type: numeric
Default Value: autosized
Range: 10 to 4294967295
Dynamic: Yes
Data Type: boolean
Default Value: OFF
--innodb-page-cleaners=#Scope: Global
Dynamic: Yes (>= ), No (<= )
Data Type: numeric
Default Value: 4 (or set to innodb_buffer_pool_instances if lower)
Range: 1 to 64
Deprecated:
Removed: MariaDB 10.6.0
64k for tables using the following row formats: DYNAMIC, COMPACT, and REDUNDANT.InnoDB's page size must still be 16k or less for tables using the COMPRESSED row format.
This system variable's value cannot be changed after the datadir has been initialized. InnoDB's page size is set when a MariaDB instance starts, and it remains constant afterwards.
Command line: --innodb-page-size=#
Scope: Global
Dynamic: No
Data Type: enumeration
Default Value: 16384
Valid Values: 4k or 4096, 8k or 8192, 16k or 16384, 32k and 64k.
Data Type: boolean
Default Value: OFF
Deprecated:
Data Type: boolean
Default Value: OFF
Data Type: numeric
Default Value:
127 (>= MariaDB 10.6.20, MariaDB 10.11.10, , MariaDB 11.4.4, )
1000 (>= MariaDB 10.6.16, , MariaDB 10.11.6, , )
300 (<= , , , , )
Range: 1 to 5000
Dynamic: Yes
Data Type: numeric
Default Value: 128
Range: 1 to 128
Deprecated: MariaDB 10.6.16, , MariaDB 10.11.6, , ,
Dynamic: No
Data Type: numeric
Default Value: 4
Range: 1 to 32
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Scope: Global
Dynamic: Yes
Data Type: enumeration
Default Value: linear
Valid Values: none, random, linear, both
Removed: /XtraDB 5.6 - replaced by MySQL 5.6's innodb_random_read_ahead
Data Type: numeric
Default Value: 56
Range: 0 to 64
Dynamic: Yes (>= MariaDB 10.11), No (<= )
Data Type: numeric
Default Value: 4
Range: 1 to 64
Data Type: boolean
Default Value: OFF
Data Type: boolean
Default Value: OFF (>= MariaDB 10.6.6), ON (<= MariaDB 10.6.5)
Introduced: MariaDB 10.6.0
Data Type: boolean
Default Value: OFF
Removed:
Dynamic: No
Data Type: boolean
Default Value: OFF
Removed: - replaced by MySQL 5.6's relay-log-recovery
Data Type: numeric
Default Value: 0
Range: 0 to 4294967295
Deprecated:
Removed: MariaDB 10.6.0
Data Type: boolean
Default Value: 0
Data Type: numeric
Default Value: 128
Range: 1 to 128
Deprecated:
Removed:
Data Type: boolean
Default Value: ON
Introduced:
Removed:
Data Type: boolean
Default Value: OFF
Deprecated:
Removed: MariaDB 10.6.0
Data Type: numeric
Default Value: 56
Range: 0 to 50000
Introduced:
Removed:
Data Type: numeric
Default Value: 256
Range: 1 to 50000
Deprecated:
Removed: MariaDB 10.6.0
Command line: innodb-sched-priority-cleaner=#
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 19
Range: 0 to 39
Deprecated:
Removed:
Data Type: numeric
Default Value: 10
Range: 0 to 1000
Deprecated:
Removed:
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range: 0 to 1
Deprecated:
Removed:
numericDefault Value: 0
Range: 0 to 99
Data Type: boolean
Default Value: ON (>= ), OFF (<= )
Introduced: MariaDB 10.6.18, MariaDB 10.11.8, , , , MariaDB 11.4.2
Data Type: numeric
Default Value: 1048576 (1M)
Range: 65536 to 67108864
Dynamic: Yes
Data Type: numeric
Default Value: 4 (>= ), 6 (<= )
Range: 0 to 4294967295
Dynamic: Yes
Data Type: boolean
Default Value: ON
booleanDefault Value: 1
Removed: - replaced by innodb_stats_auto_recalc.
Default Value: OFF
nulls_ignored: Ignore NULLs altogether from index group calculations.
See also Index Statistics, aria_stats_method and myisam_stats_method.
Command line: --innodb-stats-method=name
Scope: Global
Dynamic: Yes
Data Type: enumeration
Default Value: nulls_equal
Valid Values: nulls_equal, nulls_unequal, nulls_ignored
Data Type: numeric
Default Value: 0
Range: 0 to 18446744073709551615
Dynamic: Yes
Data Type: boolean
Default Value: OFF
Data Type: boolean
Default Value: ON
Data Type: numeric
Default Value: 20
If persistent statistics are enabled, then the innodb_stats_persistent_sample_pages system variable applies instead. persistent statistics are enabled with the innodb_stats_persistent system variable.
This system variable has been deprecated. The innodb_stats_transient_sample_pages system variable should be used instead.
Command line: --innodb-stats-sample-pages=#
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 8
Range: 1 to 2^64-1
Deprecated:
Removed:
Command line: --innodb-stats-traditional={0|1}
Scope: Global
Dynamic: Yes
Data Type: boolean
Default Value: ON
If persistent statistics are enabled, then the innodb_stats_persistent_sample_pages system variable applies instead. persistent statistics are enabled with the innodb_stats_persistent system variable.
Command line: --innodb-stats-transient-sample-pages=#
Scope: Global
Dynamic: Yes
Data Type: numeric
Default Value: 8
Range: 1 to 2^64-1
Data Type: boolean
Default Value: 1
Removed: /XtraDB 5.6
Data Type: boolean
Default Value: OFF
Data Type: boolean
Default Value: OFF
Data Type: boolean
Default Value: ON
Dynamic: Yes
Data Type: boolean
Default Value: ON
Deprecated:
Removed:
Data Type: numeric
Default Value: 1
Range: 1 to 1024
Removed: MariaDB 10.6.0
Data Type: numeric
Default Value: 30
Range: 0 to 4294967295
Dynamic: Yes
Data Type: boolean
Default Value: ON
Dynamic: Yes
Data Type: numeric
Default Value: 0
Range: 0 to 1000
Deprecated:
Removed: MariaDB 10.6.0
Data Type: boolean
Default Value: OFF
Removed: /XtraDB 5.6
Data Type: numeric
Default Value:
0 (>= .)
10000 (<= )
Range: 0 to 1000000
Deprecated:
Removed: MariaDB 10.6.0
Dynamic: No
Data Type: string
Default Value: ibtmp1:12M:autoextend
Documentation & examples: innodb-temporary-tablespaces
Data Type: string
Default Value: Empty
Dynamic: No
Data Type: boolean
Default Value: OFF
Deprecated:
Data Type: boolean
Default Value: OFF
Deprecated:
Data Type: boolean
Default Value: OFF
Introduced:
Dynamic: No
Data Type: string
Default Value: NULL
Data Type: boolean
Default Value: OFF
Dynamic: Yes
Data Type: numeric
Default Value: 128
Range: 0 to 128
Deprecated:
Removed: MariaDB 10.6.0
Command line: --innodb-undo-tablespaces=#
Scope: Global
Dynamic: No
Data Type: numeric
Default Value: 3 (>= ), 0 (<= MariaDB 10.11)
Range: 0, or 2 to 95
Data Type: boolean
Default Value: ON
innodb-use-fallocate={0|1}Scope: Global
Dynamic: No
Data Type: boolean
Default Value: OFF
Deprecated: (treated as if ON)
Removed:
Dynamic: Yes
Data Type: boolean
Default Value: ON
Deprecated:
Removed:
--innodb-use-mtflush={0|1}Scope: Global
Dynamic: No
Data Type: boolean
Default Value: OFF
Deprecated:
Removed:
Scope: Global
Dynamic: No
Data Type: boolean
Default Value: ON
Data Type: numeric
Default Value: 1
Range: 0 to 32
Removed: XtraDB 5.5
Dynamic: No
Data Type: boolean
Default Value: OFF
Deprecated:
Removed:
Dynamic: No
Data Type: boolean
Default Value: ON
Deprecated:
Removed:
Dynamic: No
Data Type: boolean
Default Value: 0
Removed: /XtraDB 5.6
Dynamic: No
Data Type: boolean
Default Value: ON
Deprecated:
Removed:
stringRemoved:
Dynamic: Yes (>= MariaDB 10.11), No (<= )
Data Type: numeric
Default Value: 4
Range: 1 to 64