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https://dev.mysql.com/doc/refman/8.4/en/myisam-table-close.html
The counter works as follows: The first time a table is updated in MySQL, a counter in the header of the index files is incremented. (The table may still be okay because MySQL always issues writes for everything between each statement.) A table was ... Each MyISAM index file (.MYI file) has a counter in the header that can be used to check whether a table has been closed ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-backup-concepts.html
A backup is a snapshot of the database at a given time. The data actually stored in the database tables at the time that the backup was made Transaction log. A sequential record telling how and when data was stored in the database Each of these ...
https://dev.mysql.com/doc/refman/8.4/en/optimizing-innodb-many-tables.html
If you have configured non-persistent optimizer statistics (a non-default configuration), InnoDB computes index cardinality values for a table the first time that table is accessed after startup, instead of storing such values in the table. This ...
https://dev.mysql.com/doc/refman/8.4/en/pattern-matching.html
MySQL provides standard SQL pattern matching as well as a form of pattern matching based on extended regular expressions similar to those used by Unix utilities such as vi, grep, and sed. SQL pattern matching enables you to use _ to match any ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-consumer-filtering.html
If you disable a consumer, the server does not spend time maintaining destinations for that consumer. If checked, they act as follows: events_statements_cpu, if NO, disables measurement of CPU_TIME. If YES, and the instrumentation is enabled and ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-data-locks-table.html
Use the data_locks table to help diagnose performance problems that occur during times of heavy concurrent load. Lock ID formats are internal and subject to change at any time. Secondary index values of the locked record are shown with primary key ...For information about which lock requests are blocked by which held locks, see Section 29.12.13.2, “The data_lock_waits ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-instrumentation-checking.html
It is always possible to determine what instruments the Performance Schema includes by checking the setup_instruments table. Changes to this code occur often, which also affects the set of instruments. It is not practical to list all the ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-table-handles-table.html
The Performance Schema exposes table lock information through the table_handles table to show the table locks currently in effect for each opened table handle. This information shows which table handles the server has open, how they are locked, and ...
https://dev.mysql.com/doc/refman/8.4/en/sys-host-summary-by-file-io.html
io_latency The total wait time of timed file I/O events for the host. By default, rows are sorted by descending total file I/O latency. The host_summary_by_file_io and x$host_summary_by_file_io views have these columns: host The host from which the ...
https://dev.mysql.com/doc/refman/8.4/en/sys-user-summary-by-file-io.html
io_latency The total wait time of timed file I/O events for the user. By default, rows are sorted by descending total file I/O latency. The user_summary_by_file_io and x$user_summary_by_file_io views have these columns: user The client user name.