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https://dev.mysql.com/doc/refman/8.4/en/innodb-performance-thread_concurrency.html
Threads waiting for locks are not counted in the number of concurrently executing threads. A thread that is waiting for a lock is given one ticket once the lock becomes available. InnoDB uses operating system threads to process requests from user ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-troubleshooting.html
If the failure is related to a deadlock, run with the innodb_print_all_deadlocks option enabled so that details about each deadlock are printed to the MySQL server error log. The following general guidelines apply to troubleshooting InnoDB ...
https://dev.mysql.com/doc/refman/8.4/en/keywords.html
Certain keywords, such as SELECT, DELETE, or BIGINT, are reserved and require special treatment for use as identifiers such as table and column names. This may also be true for the names of built-in functions. Some keywords which are otherwise ...
https://dev.mysql.com/doc/refman/8.4/en/kill.html
In most cases, it might take some time for the thread to die because the kill flag is checked only at specific intervals: During SELECT operations, for ORDER BY and GROUP BY loops, the flag is checked after reading a block of rows. During UPDATE or ... KILL [CONNECTION | QUERY] processlist_id Each connection to mysqld runs in a separate ...
https://dev.mysql.com/doc/refman/8.4/en/multiple-data-directories.html
This may lead to unpleasant surprises if your operating system does not support fault-free system locking. Usually NFS file locking is handled by the lockd daemon, but at the moment there is no platform that performs locking 100% reliably in every ... Each MySQL Instance on a machine should have its own data ...
https://dev.mysql.com/doc/refman/8.4/en/myisam-crash-recovery.html
If you run mysqld with external locking disabled (which is the default), you cannot reliably use myisamchk to check a table when mysqld is using the same table. If the server is run with external locking enabled, you can use myisamchk to check ...
https://dev.mysql.com/doc/refman/8.4/en/myisamchk-check-options.html
This is useful if you use myisamchk to check a table that is in use by some other application that does not use locking, such as mysqld when run with external locking disabled. This should be used to get full benefit of the --check-only-changed ...
https://dev.mysql.com/doc/refman/8.4/en/myisamchk-general-options.html
--wait, -w Command-Line Format --wait Type Boolean Default Value false Instead of terminating with an error if the table is locked, wait until the table is unlocked before continuing. If you are running mysqld with external locking disabled, the ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-nutshell.html
It is no longer supported in MySQL 8.4; including it in LOCK TABLES now causes a syntax error. This section summarizes what has been added to, deprecated in, changed, and removed from MySQL 8.4 since MySQL 8.0. A companion section lists MySQL ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-summary-tables.html
Summary tables provide aggregated information for terminated events over time. The tables in this group summarize event data in different ways. Each summary table has grouping columns that determine how to group the data to be aggregated, and ...