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https://dev.mysql.com/doc/refman/8.4/en/known-issues.html
Creation of a table of type MERGE does not check whether the underlying tables are compatible types. This section lists known issues in recent versions of MySQL. For information about platform-specific issues, see the installation and debugging ...
https://dev.mysql.com/doc/refman/8.4/en/loop.html
Example: CREATE PROCEDURE doiterate(p1 INT) BEGIN label1: LOOP SET p1 = p1 + 1; IF p1 < 10 THEN ITERATE label1; END IF; LEAVE label1; END LOOP label1; SET @x = p1; END; . [begin_label:] LOOP statement_list END LOOP [end_label] LOOP implements a ...
https://dev.mysql.com/doc/refman/8.4/en/mathematical-functions.html
ABS(X) Returns the absolute value of X, or NULL if X is NULL. An implication of this is that ABS(-9223372036854775808) produces an error because the result cannot be stored in a signed BIGINT value. mysql> SELECT ABS(2); -> 2 mysql> SELECT ABS(-32); ...
https://dev.mysql.com/doc/refman/8.4/en/miscellaneous-optimization-tips.html
If possible, classify reports as “live” or as “statistical”, where data needed for statistical reports is created only from summary tables that are generated periodically from the live data. This section lists a number of miscellaneous tips ...
https://dev.mysql.com/doc/refman/8.4/en/monitor-innodb-mutex-waits-performance-schema.html
A mutex is a synchronization mechanism used in the code to enforce that only one thread at a given time can have access to a common resource. When two or more threads executing in the server need to access the same resource, the threads compete ...
https://dev.mysql.com/doc/refman/8.4/en/mrr-optimization.html
The MRR optimization is not supported with secondary indexes created on virtual generated columns. Reading rows using a range scan on a secondary index can result in many random disk accesses to the base table when the table is large and not stored ...
https://dev.mysql.com/doc/refman/8.4/en/myisam-ftdump.html
Example: Suppose that the test database contains a table named mytexttable that has the following definition: CREATE TABLE mytexttable ( id INT NOT NULL, txt TEXT NOT NULL, PRIMARY KEY (id), FULLTEXT (txt) ) ENGINE=MyISAM; The index on id is index 0 ...It reads the MyISAM index file directly, so it must be run on the server host where the table is ...
https://dev.mysql.com/doc/refman/8.4/en/myisamlog.html
To create such a file, start the server with a --log-isam=log_file option. 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 ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-backup-concepts.html
In the listing just shown, backup_id stands for the backup identifier and node_id is the unique identifier for the node creating the file. A backup is a snapshot of the database at a given time. The data actually stored in the database tables at ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-backup-configuration.html
In addition, CompressedBackup causes NDB to use compression when creating and writing to backup files. You can enforce encryption of backup files by setting RequireEncryptedBackup to 1; this prevents the creation of backups without specifying ...