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https://dev.mysql.com/doc/refman/8.4/en/performance-schema-users-table.html
The users table contains a row for each user who has connected to the MySQL server. For each user name, the table counts the current and total number of connections. To set the table size explicitly, set the performance_schema_users_size system ...
https://dev.mysql.com/doc/refman/8.4/en/repair-table.html
With myisamchk --safe-recover, you can also use options that REPAIR TABLE does not support, such as --max-record-length.) REPAIR TABLE table catches and throws any errors that occur while copying table statistics from the old corrupted file to the ...[QUICK] [EXTENDED] [USE_FRM] REPAIR TABLE repairs a possibly corrupted table, for certain storage engines ...
https://dev.mysql.com/doc/refman/8.4/en/select-optimization.html
Keep table statistics up to date by using the ANALYZE TABLE statement periodically, so the optimizer has the information needed to construct an efficient execution plan. Queries, in the form of SELECT statements, perform all the lookup operations ...
https://dev.mysql.com/doc/refman/8.4/en/server-configuration.html
The MySQL server, mysqld, has many command options and system variables that can be set at startup to configure its operation. To determine the default command option and system variable values used by the server, execute this command: $> mysqld ...
https://dev.mysql.com/doc/refman/8.4/en/show-table-status.html
Notes For InnoDB tables, SHOW TABLE STATUS does not give accurate statistics except for the physical size reserved by the table. SHOW TABLE STATUS [{FROM | IN} db_name] [LIKE 'pattern' | WHERE expr] SHOW TABLE STATUS works like SHOW TABLES, but ...
https://dev.mysql.com/doc/refman/8.4/en/storage-engines.html
Storage engines are MySQL components that handle the SQL operations for different table types. InnoDB is the default and most general-purpose storage engine, and Oracle recommends using it for tables except for specialized use cases. (The CREATE ...
https://dev.mysql.com/doc/refman/8.4/en/subquery-optimization-with-exists.html
It assumes that subquery evaluations with NULL on the left side are very rare, even if there are statistics that indicate otherwise. Certain optimizations are applicable to comparisons that use the IN (or =ANY) operator to test subquery results.
https://dev.mysql.com/doc/refman/8.4/en/sys-host-summary-by-statement-latency.html
The host_summary_by_statement_latency and x$host_summary_by_statement_latency views have these columns: host The host from which the client connected. Rows for which the HOST column in the underlying Performance Schema table is NULL are assumed to ...
https://dev.mysql.com/doc/refman/8.4/en/sys-innodb-buffer-stats-by-schema.html
To avoid impacting performance on a production system, reproduce the issue you want to investigate and query buffer pool statistics on a test instance. These views summarize the information in the INFORMATION_SCHEMA INNODB_BUFFER_PAGE table, ...
https://dev.mysql.com/doc/refman/8.4/en/sys-innodb-buffer-stats-by-table.html
To avoid impacting performance on a production system, reproduce the issue you want to investigate and query buffer pool statistics on a test instance. These views summarize the information in the INFORMATION_SCHEMA INNODB_BUFFER_PAGE table, ...