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https://dev.mysql.com/doc/refman/9.7/en/partitioning-pruning.html
By limiting the search, it is possible to expend much less time and effort in finding matching rows than by scanning all partitions in the table. Pruning can also be applied for tables partitioned on a DATE or DATETIME column when the partitioning ... The optimization known as partition pruning is based on a relatively simple concept which can be described as “Do not scan partitions where there can be no matching ...
https://dev.mysql.com/doc/refman/9.7/en/partitioning-selection.html
As you can see from the result when the SELECT is run a second time, there remains a row in the table matching the WHERE condition, but residing in a different partition (p2). Explicit selection of partitions and subpartitions for rows matching a ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-and-plugins.html
Time spent executing the code while the plugin was loaded was still spent even if the plugin is unloaded later. Removing a plugin with UNINSTALL PLUGIN does not affect information already collected for code in that plugin. The associated event ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-binary-log-transaction-compression-stats-table.html
The statistics cover all transactions written to the binary log and relay log from the time the server was started or the table was truncated. FIRST_TRANSACTION_TIMESTAMP The timestamp when the first transaction was written to the log. This table ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-build-configuration.html
Because the Performance Schema is configured into the server at build time, a row for PERFORMANCE_SCHEMA appears in the output from SHOW ENGINES. It is possible to exclude certain parts of the Performance Schema instrumentation. For example, to ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-connection-tables.html
Suppose that clients named user1 and user2 each connect one time from hosta and hostb. When a client connects to the MySQL server, it does so under a particular user name and from a particular host. They differ in that, for grant tables, the host ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-data-lock-waits-table.html
Use the data_lock_waits table to help diagnose performance problems that occur during times of heavy concurrent load. The data_lock_waits table implements a many-to-many relationship showing which data lock requests in the data_locks table are ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-file-instances-table.html
If a file was opened and then closed, it was opened 1 time, but OPEN_COUNT is 0. The file_instances table lists all the files seen by the Performance Schema when executing file I/O instrumentation. If a file on disk has never been opened, it is not ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-ndb-cluster-tables.html
If synchronization of the object fails due to a temporary error, it is picked up and added back to the queue (and to this table) the next time NDB performs mismatch detection; if the attempts fails due a permanent error, the object is added to the ... The following table shows all Performance Schema tables relating to the NDBCLUSTER storage ...
https://dev.mysql.com/doc/refman/9.7/en/performance-schema-obtaining-parent-events.html
If a statement that executed a long time ago took a lock but is in a still-open transaction, it might not be possible to find the statement, but it is possible to find the transaction. Rows of this table have a THREAD_ID column indicating the thread ...