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https://dev.mysql.com/doc/refman/8.0/en/alter-database.html
On the other hand, for a function called within a SELECT, execution of the function body happens in prelocked mode. alter_option: { [DEFAULT] CHARACTER SET [=] charset_name | [DEFAULT] COLLATE [=] collation_name | [DEFAULT] ENCRYPTION [=] {'Y' | ...
https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html
The parser recognizes optimizer hint comments after the initial keyword of SELECT, UPDATE, INSERT, REPLACE, and DELETE statements. The RESOURCE_GROUP hint must appear after the initial statement keyword (SELECT, INSERT, REPLACE, UPDATE, or DELETE).
https://dev.mysql.com/doc/refman/8.0/en/replication-gtids-restrictions.html
When using GTIDs, updates to tables using nontransactional storage engines such as MyISAM cannot be made in the same statement or transaction as updates to tables using transactional storage engines such as InnoDB. This restriction is due to the ...
https://dev.mysql.com/doc/refman/8.0/en/union.html
For example, this statement is now accepted as valid: (SELECT 1 UNION SELECT 1) UNION SELECT 1; Locking clauses (FOR UPDATE, LOCK IN SHARE MODE) are allowed only in non-UNION queries. This statement is no longer accepted as valid: SELECT 1 FOR ...
https://dev.mysql.com/doc/refman/8.0/en/ansi-diff-foreign-keys.html
If ON UPDATE CASCADE or ON UPDATE SET NULL recurses to update the same table it has previously updated during the same cascade, it acts like RESTRICT. This means that you cannot use self-referential ON UPDATE CASCADE or ON UPDATE SET NULL operations. In an SQL statement that inserts, deletes, or updates many rows, foreign key constraints (like unique constraints) are checked ...For example, if you define a ...
https://dev.mysql.com/doc/refman/8.0/en/trigger-syntax.html
For example, you can have two BEFORE UPDATE triggers for a table. In an UPDATE trigger, you can use OLD.col_name to refer to the columns of a row before it is updated and NEW.col_name to refer to the columns of the row after it is updated. In a ...
https://dev.mysql.com/doc/refman/8.0/en/myisamlog.html
Invoke myisamlog like this: myisamlog [options] [file_name [tbl_name] ...] The default operation is update (-u). If a recovery is done (-r), all writes and possibly updates and deletes are done and errors are only counted. If tables are named on the ...To create such a file, start the server with a --log-isam=log_file ...
https://dev.mysql.com/doc/refman/8.0/en/replica-logs-status.html
Important Do not attempt to update or insert rows in the mysql.slave_master_info or mysql.slave_relay_log_info tables manually. Use a restricted access mode to protect database backups that include this table. With the GTID_ONLY setting, the ... A ...
https://dev.mysql.com/doc/refman/8.0/en/internal-locking.html
FOR UPDATE statement for each group of rows expected to be modified, even if the data change statements come later in the transaction. Table-Level Locking MySQL uses table-level locking for MyISAM, MEMORY, and MERGE tables, permitting only one ...
https://dev.mysql.com/doc/refman/8.0/en/table-locking.html
But because only one session can write to a table at any one time, for best performance with these other storage engines, use them primarily for tables that are queried often and rarely inserted into or updated. During the update, all other sessions ... InnoDB tables use row-level locking so that multiple sessions and applications can read from and write to the same table simultaneously, without making each other wait or producing inconsistent ...