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https://dev.mysql.com/doc/refman/8.0/en/information-schema-innodb-tablestats-table.html
The INNODB_TABLESTATS table provides a view of low-level status information about InnoDB tables. This data is used by the MySQL optimizer to calculate which index to use when querying an InnoDB table. InnoDB tables are represented in this view if ...This information is derived from in-memory data structures rather than data stored on ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-information-schema-examples.html
Note This section describes locking information as exposed by the Performance Schema data_locks and data_lock_waits tables, which supersede the INFORMATION_SCHEMA INNODB_LOCKS and INNODB_LOCK_WAITS tables in MySQL 8.0. For similar discussion ...
https://dev.mysql.com/doc/refman/8.0/en/switchable-optimizations.html
For more information, see Section 10.2.2.5, “Derived Condition Pushdown Optimization” Derived Table Merging Flags derived_merge (default on) Controls merging of derived tables and views into outer query block. The derived_merge flag controls ...
https://dev.mysql.com/doc/refman/8.0/en/tracing-example.html
Next, for every table in the query, we estimate the cost of, and number of records returned by, a table scan or a range access. "resulting_clause_is_simple": true, "resulting_clause": "`test`.`alias1`.`col_int_key`" } /* clause_processing */ }, The ...Now we can examine the trace, whose first column (QUERY), containing the original statement to be traced, is shown here: SELECT * FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE\G *************************** ...
https://dev.mysql.com/doc/refman/8.0/en/view-updatability.html
Some views are updatable and references to them can be used to specify tables to be updated in data change statements. That is, you can use them in statements such as UPDATE, DELETE, or INSERT to update the contents of the underlying table. Derived ...For dependent subqueries in the select list, no data change statements are ...
https://dev.mysql.com/doc/refman/8.0/en/implicit-commit.html
(This does not apply to other operations on temporary tables such as ALTER TABLE and CREATE INDEX, which do cause a commit.) However, although no implicit commit occurs, neither can the statement be rolled back, which means that the use of such ...
https://dev.mysql.com/doc/refman/8.0/en/myisam-storage-engine.html
(When an AUTO_INCREMENT column is defined as the last column of a multiple-column index, reuse of values deleted from the top of a sequence does occur.) The AUTO_INCREMENT value can be reset with ALTER TABLE or myisamchk. Table 18.2 MyISAM Storage ... MyISAM is based on the older (and no longer available) ISAM storage engine but has many useful ...
https://dev.mysql.com/doc/refman/8.0/en/corrupted-myisam-tables.html
Even though the MyISAM table format is very reliable (all changes to a table made by an SQL statement are written before the statement returns), you can still get corrupted tables if any of the following events occur: The mysqld process is killed ...An unexpected computer shutdown occurs (for example, the computer is turned ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-general-table-reference.html
The following table summarizes INFORMATION_SCHEMA general tables. For greater detail, see the individual table descriptions. Table 28.2 INFORMATION_SCHEMA General Tables Table Name Description Introduced Deprecated ADMINISTRABLE_ROLE_AUTHORIZATIONS ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-programs-ndb-show-tables.html
ndb_show_tables displays a list of all NDB database objects in the cluster. By default, this includes not only both user-created tables and NDB system tables, but NDB-specific indexes, internal triggers, and NDB Cluster Disk Data objects as well.