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https://dev.mysql.com/doc/refman/8.0/en/atomic-ddl.html
An atomic DDL statement combines the data dictionary updates, storage engine operations, and binary log writes associated with a DDL operation into a single, atomic operation. Atomic DDL is made possible by the introduction of the MySQL data ...The ...
https://dev.mysql.com/doc/refman/8.0/en/create-table-check-constraints.html
Prior to MySQL 8.0.16, CREATE TABLE permits only the following limited version of table CHECK constraint syntax, which is parsed and ignored: CHECK (expr) As of MySQL 8.0.16, CREATE TABLE permits the core features of table and column CHECK ...If ...
https://dev.mysql.com/doc/refman/8.0/en/get-diagnostics.html
GET DIAGNOSTICS can obtain either statement or condition information, but not both in the same statement: To obtain statement information, retrieve the desired statement items into target variables. This instance of GET DIAGNOSTICS assigns the ...
https://dev.mysql.com/doc/refman/8.0/en/hash-joins.html
It is possible to control whether hash joins are employed using one of the BNL and NO_BNL optimizer hints, or by setting block_nested_loop=on or block_nested_loop=off as part of the setting for the optimizer_switch server system variable. Note MySQL ... By default, MySQL (8.0.18 and later) employs hash joins whenever ...
https://dev.mysql.com/doc/refman/8.0/en/index-page-merge-threshold.html
row *************************** Table: t2 Create Table: CREATE TABLE `t2` ( `id` int(11) DEFAULT NULL, KEY `id_index` (`id`) COMMENT 'MERGE_THRESHOLD=40' ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci Note A MERGE_THRESHOLD value ...If the “page-full” percentage for an index page falls below the MERGE_THRESHOLD value when a row is deleted or when a row is shortened by an UPDATE operation, InnoDB attempts to merge the index page with a neighboring index ...
https://dev.mysql.com/doc/refman/8.0/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 COLLATE=utf8mb4_0900_ai_ci; However, metadata for such a column does appear in the ... The ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-key-column-usage-table.html
The KEY_COLUMN_USAGE table has these columns: CONSTRAINT_CATALOG The name of the catalog to which the constraint belongs. CONSTRAINT_SCHEMA The name of the schema (database) to which the constraint belongs. If the constraint is a foreign key, then ...This table provides no information about functional key parts because they are expressions and the table provides information only about ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-online-ddl-operations.html
To avoid uncertainty and the potential space requirement for an extra hidden column, specify the PRIMARY KEY clause as part of the CREATE TABLE statement. The change buffer is not used, because there are no random-access inserts into the secondary ... Online support details, syntax examples, and usage notes for DDL operations are provided under the following topics in this ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-row-format.html
As more rows fit into a single disk page, queries and index lookups can work faster, less cache memory is required in the buffer pool, and less I/O is required to write out updated values. In addition, there is a 6-byte transaction ID field and a ...
https://dev.mysql.com/doc/refman/8.0/en/partitioning-management-exchange.html
To see how this occurs, first insert a row into e2 that is outside the boundaries of the partition definition for partition p0 of table e. Table nt contains no foreign key references, and no other table has any foreign keys that refer to nt. There ...