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https://dev.mysql.com/doc/refman/8.4/en/explain.html
In practice, the DESCRIBE keyword is more often used to obtain information about table structure, whereas EXPLAIN is used to obtain a query execution plan (that is, an explanation of how MySQL would execute a query). The following discussion uses ...
https://dev.mysql.com/doc/refman/8.4/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. row ...
https://dev.mysql.com/doc/refman/8.4/en/index-page-merge-threshold.html
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 page. The default ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-virtual-table.html
The INNODB_VIRTUAL table provides metadata about InnoDB virtual generated columns and columns upon which virtual generated columns are based. A row appears in the INNODB_VIRTUAL table for each column upon which a virtual generated column is based.
https://dev.mysql.com/doc/refman/8.4/en/information-schema-key-column-usage-table.html
This table provides no information about functional key parts because they are expressions and the table provides information only about columns. The KEY_COLUMN_USAGE table has these columns: CONSTRAINT_CATALOG The name of the catalog to which the ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-online-ddl-operations.html
Online support details, syntax examples, and usage notes for DDL operations are provided under the following topics in this section. Index Operations Primary Key Operations Column Operations Generated Column Operations Foreign Key Operations Table ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-row-format.html
The row format of a table determines how its rows are physically stored, which in turn can affect the performance of queries and DML operations. As more rows fit into a single disk page, queries and index lookups can work faster, less cache memory ...
https://dev.mysql.com/doc/refman/8.4/en/partitioning-management-exchange.html
Table nt contains no foreign key references, and no other table has any foreign keys that refer to nt. There are no rows in nt that lie outside the boundaries of the partition definition for p. For InnoDB tables, both tables must use the same row ...
https://dev.mysql.com/doc/refman/8.4/en/switchable-optimizations.html
Its value is a set of flags, each of which has a value of on or off to indicate whether the corresponding optimizer behavior is enabled or disabled. This variable has global and session values and can be changed at runtime. To see the current set of ...
https://dev.mysql.com/doc/refman/8.4/en/trigger-syntax.html
To create a trigger or drop a trigger, use the CREATE TRIGGER or DROP TRIGGER statement, described in Section 15.1.22, “CREATE TRIGGER Statement”, and Section 15.1.34, “DROP TRIGGER Statement”. Here is a simple example that associates a ...