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https://dev.mysql.com/doc/refman/8.0/en/performance-schema-filtering.html
The setup_instruments table lists the instruments for which events can be collected, whether they are enabled, and (for enabled instruments) whether to collect timing information: mysql> SELECT NAME, ENABLED, TIMED FROM ... Events are processed in a ...| wait/synch/mutex/sql/LOCK_global_read_lock | YES | YES | | wait/synch/mutex/sql/LOCK_global_system_variables | YES | YES | | wait/synch/mutex/sql/LOCK_lock_db | YES | YES | | wait/synch/mutex/sql/LOCK_manager | YES | YES | ...
https://dev.mysql.com/doc/refman/8.0/en/performance-schema-socket-instances-table.html
The socket_instances table provides a real-time snapshot of the active connections to the MySQL server. Information available in this table provides a real-time snapshot of the active connections to the server. (Additional information is available ...The table contains one row per TCP/IP or Unix socket file ...
https://dev.mysql.com/doc/refman/8.0/en/partitioning-limitations-partitioning-keys-unique-keys.html
This section discusses the relationship of partitioning keys with primary keys and unique keys. However, you can add a unique key that uses both c1 and c2. The rule governing this relationship can be expressed as follows: All columns used in the ...
https://dev.mysql.com/doc/refman/8.0/en/performance-schema-setup-objects-table.html
For existing rows, only the ENABLED and TIMED columns can be modified, by users with the UPDATE privilege on the table. The order in which matching occurs matters because different matching setup_objects rows can have different ENABLED and TIMED ...
https://dev.mysql.com/doc/refman/8.0/en/replication-features-timeout.html
This data includes timestamps showing how long it took the applier thread to apply the last transaction from start to finish (and when the transaction currently in progress was started), and how long this was after the commit on the original source ... The global value of the system variable replica_transaction_retries (from MySQL 8.0.26) or slave_transaction_retries (before MySQL 8.0.26) sets the maximum number of times for applier threads on a single-threaded or multithreaded replica to automatically retry failed transactions before ...
https://dev.mysql.com/doc/refman/8.0/en/optimizing-myisam-bulk-data-loading.html
This does not update any indexes and therefore is very fast. If you use locking, connections 2, 3, and 4 probably do not finish before 1 or 5, but the total time should be about 40% faster. INSERT, UPDATE, and DELETE operations are very fast in ...
https://dev.mysql.com/doc/refman/8.0/en/optimizing-queries-myisam.html
If you often need to calculate results such as counts based on information from a lot of rows, it may be preferable to introduce a new table and update the counter in real time. Try to avoid complex SELECT queries on MyISAM tables that are updated ...This updates a value for each index part that indicates the average number of rows that have the same ... Some general tips for speeding up queries on MyISAM tables: To help MySQL better ...
https://dev.mysql.com/doc/refman/8.0/en/replication-bugs.html
When you have determined that there is no user error involved, and replication still either does not work at all or is unstable, it is time to send us a bug report. Please spend some time and effort in preparing a good bug report. For example, if ...In this case, the replication thread stops and waits for you to clean up the tables manually to bring them into ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-params-api.html
The listing in this section provides information about parameters used in the [mysqld] and [api] sections of a config.ini file for configuring NDB Cluster SQL nodes and API nodes. For detailed descriptions and other additional information about ...
https://dev.mysql.com/doc/refman/8.0/en/group-replication-probes-and-statistics.html
The monitoring mechanism works by having each member deploying a set of probes to collect information about its work queues and throughput. Such probes are scattered throughout the plugin stack and allow one to establish metrics, such as: the ...It ...