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https://dev.mysql.com/doc/refman/8.4/en/json-attribute-functions.html
The functions in this section return attributes of JSON values. An error occurs if the argument is not a valid JSON document. An empty array, empty object, or scalar value has depth 1. A nonempty array containing only elements of depth 1 or ...
https://dev.mysql.com/doc/refman/8.4/en/json.html
The JSON data type provides these advantages over storing JSON-format strings in a string column: Automatic validation of JSON documents stored in JSON columns. JSON documents stored in JSON columns are converted to an internal format that permits ...
https://dev.mysql.com/doc/refman/8.4/en/loop.html
[begin_label:] LOOP statement_list END LOOP [end_label] LOOP implements a simple loop construct, enabling repeated execution of the statement list, which consists of one or more statements, each terminated by a semicolon (;) statement delimiter.
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/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/multiple-column-indexes.html
MySQL can create composite indexes (that is, indexes on multiple columns). For certain data types, you can index a prefix of the column (see Section 10.3.5, “Column Indexes”). MySQL can use multiple-column indexes for queries that test all the ...
https://dev.mysql.com/doc/refman/8.4/en/myisam-ftdump.html
It reads the MyISAM index file directly, so it must be run on the server host where the table is located. Before using myisam_ftdump, be sure to issue a FLUSH TABLES statement first if the server is running. myisam_ftdump scans and dumps the entire ...
https://dev.mysql.com/doc/refman/8.4/en/myisam-storage-engine.html
MyISAM is based on the older (and no longer available) ISAM storage engine but has many useful extensions. Table 18.2 MyISAM Storage Engine Features Feature Support B-tree indexes Yes Backup/point-in-time recovery (Implemented in the server, rather ...
https://dev.mysql.com/doc/refman/8.4/en/myisamchk-table-info.html
To obtain a description of a MyISAM table or statistics about it, use the commands shown here. The output from these commands is explained later in this section. myisamchk -d tbl_name Runs myisamchk in “describe mode” to produce a description ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-limitations-unsupported.html
A number of features supported by other storage engines are not supported for NDB tables. Trying to use any of these features in NDB Cluster does not cause errors in or of itself; however, errors may occur in applications that expects the features ...