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https://dev.mysql.com/doc/refman/8.4/en/sys-waits-by-user-by-latency.html
These views summarize wait events, grouped by user and event. By default, rows are sorted by user and descending total latency. The waits_by_user_by_latency and x$waits_by_user_by_latency views have these columns: user The user associated with the ...
https://dev.mysql.com/doc/refman/8.4/en/sys-waits-global-by-latency.html
The waits_global_by_latency and x$waits_global_by_latency views have these columns: events The event name. total_latency The total wait time of timed occurrences of the event. avg_latency The average wait time per timed occurrence of the event.
https://dev.mysql.com/doc/refman/8.4/en/telemetry-metrics-meter-metrics.html
notified_by_group_replication Mysqlx_notified_by_group_replication ASYNC COUNTER Number of Group Replication notifications sent to clients. The following server metrics are registered by default: mysql.stats Metrics mysql.stats.com Metrics ...
https://dev.mysql.com/doc/refman/8.4/en/telemetry-metrics-meters.html
For example, to update the frequency of the mysql.inno metrics: mysql>update performance_schema.setup_meters set FREQUENCY='30' where name = 'mysql.inno'; The maximum number of meter instruments which can be created is set by ...
https://dev.mysql.com/doc/refman/8.4/en/temporary-files.html
(In such cases, lsof +L1 may be helpful in identifying large files associated with mysqld.) When sorting (ORDER BY or GROUP BY), MySQL normally uses one or two temporary files. On Unix, MySQL uses the value of the TMPDIR environment variable as the ...
https://dev.mysql.com/doc/refman/8.4/en/upgrading-from-previous-series.html
The following variables are excepted from this restriction: admin_ssl_ca, admin_ssl_capath, admin_ssl_cert, admin_ssl_cipher, admin_tls_ciphersuites, admin_ssl_key, admin_ssl_crl, admin_ssl_crlpath, basedir, character_sets_dir, ft_stopword_file, ...
https://dev.mysql.com/doc/refman/8.4/en/upgrading-what-is-upgraded.html
Note that following an upgrade with this option, Group Replication cannot be started, because system tables on which the replication internals depend are not updated, and reduced functionality might also be apparent in other areas. Installing a new ...
https://dev.mysql.com/doc/refman/8.4/en/user-variables.html
HAVING, GROUP BY, and ORDER BY, when referring to a variable that is assigned a value in the select expression list do not work as expected because the expression is evaluated on the client and thus can use stale column values from a previous row.
https://dev.mysql.com/doc/refman/8.4/en/view-updatability.html
Some views are updatable and references to them can be used to specify tables to be updated in data change statements. That is, you can use them in statements such as UPDATE, DELETE, or INSERT to update the contents of the underlying table. Derived ...
https://dev.mysql.com/doc/refman/8.4/en/window-function-optimization.html
Window functions affect the strategies the optimizer considers: Derived table merging for a subquery is disabled if the subquery has window functions. Semijoins are not applicable to window function optimization because semijoins apply to ...