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https://dev.mysql.com/doc/refman/8.4/en/innodb-persistent-stats.html
The persistent optimizer statistics feature improves plan stability by storing statistics to disk and making them persistent across server restarts so that the optimizer is more likely to make consistent choices each time for a given query.
https://dev.mysql.com/doc/refman/8.4/en/innodb-recovery.html
The innodb_directories default setting is NULL, but the directories defined by innodb_data_home_dir, innodb_undo_directory, and datadir are always appended to the innodb_directories argument value when InnoDB builds a list of directories to scan at ...To achieve point-in-time recovery after restoring a backup, you can apply changes from the binary log that occurred after the backup was ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-temporary-tablespace.html
row *************************** FILE_NAME: ./ibtmp1 TABLESPACE_NAME: innodb_temporary ENGINE: InnoDB INITIAL_SIZE: 12582912 TotalSizeBytes: 12582912 DATA_FREE: 6291456 MAXIMUM_SIZE: NULL TotalSizeBytes shows the current size of the global temporary ... InnoDB uses session temporary tablespaces and a global temporary ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-transaction-scheduling.html
A transaction that is not waiting for a lock reports a NULL TRX_SCHEDULE_WEIGHT value. InnoDB uses the Contention-Aware Transaction Scheduling (CATS) algorithm to prioritize transactions that are waiting for locks. When multiple transactions are ...
https://dev.mysql.com/doc/refman/8.4/en/kill.html
KILL [CONNECTION | QUERY] processlist_id Each connection to mysqld runs in a separate thread. Thread processlist identifiers can be determined from the ID column of the INFORMATION_SCHEMA PROCESSLIST table, the Id column of SHOW PROCESSLIST output, ...
https://dev.mysql.com/doc/refman/8.4/en/log-file-maintenance.html
For example, execute these commands as root: mv /var/log/mysqld.log /var/log/mysqld.log.old install -omysql -gmysql -m0644 /dev/null /var/log/mysqld.log . As described in Section 7.4, “MySQL Server Logs”, MySQL Server can create several ...
https://dev.mysql.com/doc/refman/8.4/en/myisamchk.html
The myisamchk utility gets information about your database tables or checks, repairs, or optimizes them. myisamchk works with MyISAM tables (tables that have .MYD and .MYI files for storing data and indexes). You can also use the CHECK TABLE and ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-limitations-performance.html
Unique hash indexes created with USING HASH cannot be used for accessing a table if NULL is given as part of the key. The following performance issues are specific to or especially pronounced in NDB Cluster: Range scans. There are query performance ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-memory-per-fragment.html
memory_per_fragment Table: Notes memory_per_fragment Table: Examples The memory_per_fragment table provides information about the usage of memory by individual fragments. See the Notes later in this section to see how you can use this to find out ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ps-tables.html
row *************************** NAME: memory/ndbcluster/Thd_ndb::batch_mem_root ENABLED: YES TIMED: NULL PROPERTIES: VOLATILITY: 0 DOCUMENTATION: Memory used for transaction batching 1 row in set (0.01 sec) . NDB provides information in the MySQL ...