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https://dev.mysql.com/doc/internals/en/optimizer-determining-join-type.html
When evaluating a conditional expression, MySQL decides what join type the expression has. (Again: despite the word “join”, this applies for all conditional expressions, not just join expressions. index: a sequential scan on an index ALL: a ...
https://dev.mysql.com/doc/internals/en/optimizer-group-by-related-conditions.html
Note that the query SELECT COUNT(column1) FROM Table1; is not subject to the same optimization, unless column1 is defined as NOT NULL. (You can, however, rely on that rule with GROUP BY, unless the query includes ORDER BY NULL.) See: ... These are ...
https://dev.mysql.com/doc/internals/en/stability-checks-for-random-timing-problems.html
Examples: all OS: Compile a MySQL version from source Unix derivates (OpenSolaris,Linux,OSX,...): tar -chvf - <some path> > /dev/null Unix derivates: root: dd if=<area of disk containing the "var" directory> of=/dev/null Windows: Defragmentation ...
https://dev.mysql.com/doc/internals/en/starting-transaction-from-start-stmt-call.html
The first method call that can start a transaction is the [custom-engine.html#custom-engine-transactions-starting-start-stmt start_stmt()] method. It holds state relevant data for the current client, such as identity, network connection and other ...
https://dev.mysql.com/doc/internals/en/the-myi-file.html
It appears once for each field that appears in a key, including an extra field that appears at the start and has flags (for deletion and for null fields). These facts are not illustrated, but are also clear: If a key value is NULL, then the first ...
https://dev.mysql.com/doc/mysqld-version-reference/en/built-in-functions.html
The following table shows all built-in functions and operators available in MySQL Server. Introduced: The version or versions in which the item was introduced. Deprecated: The version or versions in which the item was deprecated. Removed: The ...
https://dev.mysql.com/doc/mysqld-version-reference/en/keywords-8-4.html
This section provides information about keywords and reserved words in MySQL 8.4. MySQL 8.4 Keywords and Reserved Words MySQL 8.4 New Keywords and Reserved Words MySQL 8.4 Removed Keywords and Reserved Words MySQL 8.4 Keywords and Reserved Words ...
https://dev.mysql.com/doc/mysqld-version-reference/en/keywords-9-3.html
This section provides information about keywords and reserved words in MySQL 9.3. MySQL 9.3 Keywords and Reserved Words MySQL 9.3 New Keywords and Reserved Words MySQL 9.3 Removed Keywords and Reserved Words MySQL 9.3 Keywords and Reserved Words ...
https://dev.mysql.com/doc/mysqld-version-reference/en/keywords-9-4.html
This section provides information about keywords and reserved words in MySQL 9.4. MySQL 9.4 Keywords and Reserved Words MySQL 9.4 New Keywords and Reserved Words MySQL 9.4 Removed Keywords and Reserved Words MySQL 9.4 Keywords and Reserved Words ...
https://dev.mysql.com/doc/mysqld-version-reference/en/keywords-9-5.html
This section provides information about keywords and reserved words in MySQL 9.5. MySQL 9.5 Keywords and Reserved Words MySQL 9.5 New Keywords and Reserved Words MySQL 9.5 Removed Keywords and Reserved Words MySQL 9.5 Keywords and Reserved Words ...