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https://dev.mysql.com/doc/refman/9.7/en/dynamic-format.html
NULL columns require additional space in the row to record whether their values are NULL. Each NULL column takes one bit extra, rounded up to the nearest byte. Dynamic storage format is used if a MyISAM table contains any variable-length columns ...
https://dev.mysql.com/doc/refman/9.7/en/events-privileges.html
To enable or disable the execution of scheduled events, it is necessary to set the value of the global event_scheduler system variable. The EVENT privilege governs the creation, modification, and deletion of events. For example, suppose that ...
https://dev.mysql.com/doc/refman/9.7/en/gis-format-conversion-functions.html
If the options argument is NULL, the return value is NULL. MySQL supports the functions listed in this section for converting geometry values from internal geometry format to WKT or WKB format, or for swapping the order of X and Y coordinates.
https://dev.mysql.com/doc/refman/9.7/en/gis-wkt-functions.html
If the options argument is NULL, the return value is NULL. These functions take as arguments a Well-Known Text (WKT) representation and, optionally, a spatial reference system identifier (SRID). For a description of WKT format, see Well-Known Text ...
https://dev.mysql.com/doc/refman/9.7/en/gtid-functions.html
timeout must be greater than or equal to 0; when running in strict SQL mode, a negative timeout value is immediately rejected with an error (ER_WRONG_ARGUMENTS); otherwise the function returns NULL, and raises a warning. The functions described in ...
https://dev.mysql.com/doc/refman/9.7/en/information-schema-innodb-metrics-table.html
row *************************** NAME: dml_inserts SUBSYSTEM: dml COUNT: 3 MAX_COUNT: 3 MIN_COUNT: NULL AVG_COUNT: 0.046153846153846156 COUNT_RESET: 3 MAX_COUNT_RESET: 3 MIN_COUNT_RESET: NULL AVG_COUNT_RESET: NULL TIME_ENABLED: 2014-12-04 14:18:28 ...
https://dev.mysql.com/doc/refman/9.7/en/information-schema-innodb-virtual-table.html
CREATE TABLE `t1` ( `a` int(11) DEFAULT NULL, `b` int(11) DEFAULT NULL, `c` int(11) GENERATED ALWAYS AS (5) VIRTUAL ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4; However, metadata for such a column does appear in the INNODB_COLUMNS table. The ...
https://dev.mysql.com/doc/refman/9.7/en/information-schema-tables-table.html
Not all storage engines update this time, in which case, the value is always NULL. For views, most TABLES columns are 0 or NULL except that TABLE_NAME indicates the view name, CREATE_TIME indicates the creation time, and TABLE_COMMENT says VIEW. The ...
https://dev.mysql.com/doc/refman/9.7/en/innodb-fulltext-index.html
If you want to create your own FTS_DOC_ID column, the column must be defined as BIGINT UNSIGNED NOT NULL and named FTS_DOC_ID (all uppercase), as in the following example: Note The FTS_DOC_ID column does not need to be defined as an AUTO_INCREMENT ... Full-text indexes are created on text-based columns (CHAR, VARCHAR, or TEXT columns) to speed up queries and DML operations on data contained within those ...
https://dev.mysql.com/doc/refman/9.7/en/innodb-optimize-tablespace-page-allocation.html
By default, when additional space is required, InnoDB allocates pages to the tablespace and physically writes NULLs to those pages. You can disable innodb_extend_and_initialize on Linux systems to avoid physically writing NULLs to newly allocated ...