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https://dev.mysql.com/doc/refman/5.7/en/create-table-foreign-keys.html
A foreign key relationship involves a parent table that holds the initial column values, and a child table with column values that reference the parent column values. Corresponding columns in the foreign key and the referenced key must have similar ... MySQL supports foreign keys, which permit cross-referencing related data across tables, and foreign key constraints, which help keep the related data ...
https://dev.mysql.com/doc/refman/5.7/en/partitioning-limitations.html
No InnoDB table definition may contain a foreign key reference to a user-partitioned table; no InnoDB table with user-defined partitioning may contain columns referenced by foreign keys. ORDER BY column statement run against a partitioned table ...
https://dev.mysql.com/doc/refman/5.7/en/json.html
The JSON data type provides these advantages over storing JSON-format strings in a string column: Automatic validation of JSON documents stored in JSON columns. JSON documents stored in JSON columns are converted to an internal format that permits ...When the server later must read a JSON value stored in this binary format, the value need not be parsed from a text ...
https://dev.mysql.com/doc/refman/5.7/en/migrating-from-year2.html
This section describes problems that can occur when using the 2-digit YEAR(2) data type and provides information about converting existing YEAR(2) columns to 4-digit year-valued columns, which can be declared as YEAR with an implicit display width ...Although the internal range of values for YEAR/YEAR(4) and the deprecated YEAR(2) type is the same (1901 to 2155, and 0000), the display width for YEAR(2) makes that type inherently ambiguous because displayed values indicate only the last two digits of the internal values and omit the century ...
https://dev.mysql.com/doc/refman/5.7/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 ...This ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-fulltext-index.html
Full-text indexes are created on text-based columns (CHAR, VARCHAR, or TEXT columns) to speed up queries and DML operations on data contained within those columns. When a full-text index is dropped, the FTS_DOC_ID column that was created for the ...
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-limitations-syntax.html
Keys and indexes on NDB Cluster tables are subject to the following limitations: Column width. Attempting to create an index on an NDB table column whose width is greater than 3072 bytes is rejected with ER_TOO_LONG_KEY: Specified key was too long; ... Some SQL statements relating to certain MySQL features produce errors when used with NDB tables, as described in the following list: Temporary ...
https://dev.mysql.com/doc/refman/5.7/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/5.7/en/enum.html
An ENUM is a string object with a value chosen from a list of permitted values that are enumerated explicitly in the column specification at table creation time. The ENUM type has these advantages: Compact data storage in situations where a column ...See Section 11.3.1, “String Data Type Syntax” for ENUM type syntax and length ...
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-replication-schema.html
0 in the epoch column of this table indicates a transaction originating from a storage engine other than NDB. When mysqld is started with the --ndb-log-orig option, the orig_server_id and orig_epoch columns store, respectively, the ID of the server ... ndb_apply_status Table ndb_binlog_index Table ndb_replication Table Replication in NDB Cluster makes use of a number of dedicated tables in the mysql database on each MySQL Server instance acting as an SQL node in both the cluster being replicated and in the ...