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https://dev.mysql.com/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/tablespace-copying.html
IMPORT TABLESPACE does not enforce foreign key constraints on imported data. If there are foreign key constraints between tables, all tables should be exported at the same (logical) point in time. Importing a tablespace file from another MySQL ...
https://dev.mysql.com/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 Note A MERGE_THRESHOLD value defined at the index level ...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/trigger-syntax.html
The trigger acts as an accumulator, summing the values inserted into one of the columns of the table. In this case, the trigger activates before each row inserted into the table. In the example, the trigger body is a simple SET that accumulates into ... To create a trigger or drop a trigger, use the CREATE TRIGGER or DROP TRIGGER statement, described in Section 13.1.22, “CREATE TRIGGER Syntax”, and Section 13.1.34, “DROP TRIGGER ...
https://dev.mysql.com/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/innodb-information-schema-system-tables.html
The InnoDB INFORMATION_SCHEMA table interface allows you to query this data using SQL. As a final step, insert a row into table t1 (TABLE_ID = 71) and view the data in the INNODB_TABLESTATS table. mysql> INSERT INTO t1 VALUES(5, 'abc', 'def'); Query ... You can extract metadata about schema objects managed by InnoDB using InnoDB INFORMATION_SCHEMA ...
https://dev.mysql.com/c-api-asynchronous-interface.html
CREATE DATABASE db; USE db; CREATE TABLE test_table (id INT NOT NULL); INSERT INTO test_table VALUES (10), (20), (30); CREATE USER 'testuser'@'localhost' IDENTIFIED BY 'testpass'; GRANT ALL ON db.* TO 'testuser'@'localhost'; Create a file named ...
https://dev.mysql.com/innodb-transaction-isolation-levels.html
For other search conditions, InnoDB locks the index range scanned, using gap locks or next-key locks to block insertions by other sessions into the gaps covered by the range. Gap locking is only used for foreign-key constraint checking and ...
https://dev.mysql.com/create-tablespace.html
The UNDO keyword, introduced in MySQL 8.0.14, must be specified to create an undo tablespace. The unique file name is a 128 bit UUID formatted into five groups of hexadecimal numbers separated by dashes (aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee). The ...
https://dev.mysql.com/invisible-indexes.html
If an index made invisible actually is needed or used by the optimizer, there are several ways to notice the effect of its absence on queries for the table: Errors occur for queries that include index hints that refer to the invisible index. If the ... MySQL supports invisible indexes; that is, indexes that are not used by the ...
Document created the 26/06/2006, last modified the 26/10/2018
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