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https://dev.mysql.com/doc/refman/8.4/en/performance-schema-host-cache-table.html
The host_cache_size system variable controls the size of the host cache, as well as the size of the host_cache table. Because the host_cache table exposes the contents of the host cache, it can be examined using SELECT statements. The host_cache ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-log-status-table.html
The log_status table provides information that enables an online backup tool to copy the required log files without locking those resources for the duration of the copy process. When the log_status table is queried, the server blocks logging and ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-metadata-locks-table.html
Metadata locking applies not just to tables, but also to schemas, stored programs (procedures, functions, triggers, scheduled events), tablespaces, user locks acquired with the GET_LOCK() function (see Section 14.14, “Locking Functions”), and ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-socket-instances-table.html
The socket_instances table provides a real-time snapshot of the active connections to the MySQL server. The table contains one row per TCP/IP or Unix socket file connection. Information available in this table provides a real-time snapshot of the ...row *************************** EVENT_NAME: wait/io/socket/sql/server_unix_socket OBJECT_INSTANCE_BEGIN: 4316619408 THREAD_ID: 1 SOCKET_ID: 16 IP: PORT: 0 STATE: ACTIVE *************************** ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-socket-summary-tables.html
These socket summary tables aggregate timer and byte count information for socket operations: socket_summary_by_event_name: Aggregate timer and byte count statistics generated by the wait/io/socket/* instruments for all socket I/O operations, per ...socket_summary_by_instance: Aggregate timer and byte count statistics generated by the wait/io/socket/* instruments for all socket I/O operations, per socket ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-table-reference.html
The following table summarizes all available Performance Schema tables. For greater detail, see the individual table descriptions. Table 29.1 Performance Schema Tables Table Name Description accounts Connection statistics per client account ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-wait-tables.html
These tables store wait events: events_waits_current: The current wait event for each thread. There are also summary tables that aggregate information about wait events; see Section 29.12.20.1, “Wait Event Summary Tables”. For more information ... The Performance Schema instruments waits, which are events that take ...
https://dev.mysql.com/doc/refman/8.4/en/repair-table-optimization.html
REPAIR TABLE for MyISAM tables is similar to using myisamchk for repair operations, and some of the same performance optimizations apply: myisamchk has variables that control memory allocation. For REPAIR TABLE, the same principle applies, but ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-triggers-table.html
To see information about a table's triggers, you must have the TRIGGER privilege for the table. The TRIGGERS table has these columns: TRIGGER_CATALOG The name of the catalog to which the trigger belongs. This is the type of operation on the ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-setup-threads-table.html
For background threads, setting the ENABLED value controls whether INSTRUMENTED is set to YES or NO for threads that are subsequently created for this instrument and listed in the threads table. For background threads, setting the HISTORY value ...