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https://dev.mysql.com/doc/refman/9.7/en/srjs-webassembly.html
This section discusses compilation of C, C++, or other code to WebAssembly, incorporating the compiled code into a MySQL library, and using such a library in MySQL JavaScript programs. In the examples that follow, to compile C code to WebAssembly, ...
https://dev.mysql.com/doc/refman/9.7/en/alter-table-partition-operations.html
Partitioning-related clauses for ALTER TABLE can be used with partitioned tables for repartitioning, to add, drop, discard, import, merge, and split partitions, and to perform partitioning maintenance. This option is intended for use chiefly when ...Simply using a partition_options clause with ALTER TABLE on a partitioned table repartitions the table according to the partitioning scheme defined by the ...
https://dev.mysql.com/doc/refman/9.7/en/create-table-check-constraints.html
CREATE TABLE permits the core features of table and column CHECK constraints, for all storage engines. CREATE TABLE permits the following CHECK constraint syntax, for both table constraints and column constraints: [CONSTRAINT [symbol]] CHECK (expr) ...If omitted, MySQL generates a name from the table name, a literal _chk_, and an ordinal number (1, 2, 3, ...
https://dev.mysql.com/doc/refman/9.7/en/explain.html
MySQL 9.7 supports an additional INTO option with EXPLAIN FORMAT=JSON, which enables saving the JSON formatted output into a user variable, like this: mysql> EXPLAIN FORMAT=JSON INTO @myselect -> SELECT name FROM a WHERE id = 2; Query OK, 0 rows ...
https://dev.mysql.com/doc/refman/9.7/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. It is ...
https://dev.mysql.com/doc/refman/9.7/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/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-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/9.7/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/9.7/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 ...