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https://dev.mysql.com/doc/refman/8.4/en/create-table-foreign-keys.html
MySQL supports foreign keys, which permit cross-referencing related data across tables, and foreign key constraints, which help keep the related data consistent. A foreign key relationship involves a parent table that holds the initial column ...
https://dev.mysql.com/doc/refman/8.4/en/general-tablespaces.html
A general tablespace is a shared InnoDB tablespace that is created using CREATE TABLESPACE syntax. The server keeps tablespace metadata in memory for the lifetime of a tablespace. Multiple tables in fewer general tablespaces consume less memory for ...
https://dev.mysql.com/doc/refman/8.4/en/group-by-handling.html
SQL-92 and earlier does not permit queries for which the select list, HAVING condition, or ORDER BY list refer to nonaggregated columns that are not named in the GROUP BY clause. SQL:1999 and later permits such nonaggregates per optional feature ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-referential-constraints-table.html
The REFERENTIAL_CONSTRAINTS 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. UNIQUE_CONSTRAINT_CATALOG The name ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-auto-increment-handling.html
InnoDB provides a configurable locking mechanism that can significantly improve scalability and performance of SQL statements that add rows to tables with AUTO_INCREMENT columns. To use the AUTO_INCREMENT mechanism with an InnoDB table, an ...
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/invisible-columns.html
An invisible column is normally hidden to queries, but can be accessed if explicitly referenced. As an illustration of when invisible columns may be useful, suppose that an application uses SELECT * queries to access a table, and must continue to ...
https://dev.mysql.com/doc/refman/8.4/en/known-issues.html
This section lists known issues in recent versions of MySQL. For information about platform-specific issues, see the installation and debugging instructions in Section 2.1, “General Installation Guidance”, and Section 7.9, “Debugging MySQL”. The following problems are known: Subquery optimization for IN is not as effective as for ...
https://dev.mysql.com/doc/refman/8.4/en/memory-storage-engine.html
The MEMORY storage engine (formerly known as HEAP) creates special-purpose tables with contents that are stored in memory. Because the data is vulnerable to crashes, hardware issues, or power outages, only use these tables as temporary work areas ...
https://dev.mysql.com/doc/refman/8.4/en/merge-storage-engine.html
The MERGE storage engine, also known as the MRG_MyISAM engine, is a collection of identical MyISAM tables that can be used as one. “Identical” means that all tables have identical column data types and index information. You cannot merge MyISAM ...