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https://dev.mysql.com/doc/refman/8.4/en/constraint-foreign-key.html
MySQL supports ON UPDATE and ON DELETE foreign key references in CREATE TABLE and ALTER TABLE statements. MySQL requires that foreign key columns be indexed; if you create a table with a foreign key constraint but no index on a given column, an ...
https://dev.mysql.com/doc/refman/8.4/en/identifier-mapping.html
If you are using tablespaces with InnoDB, then the specific tablespace files you create are used instead. MySQL encodes any characters that are problematic in the corresponding file system objects when it creates database directories or table files: ... There is a correspondence between database and table identifiers and names in the file ...
https://dev.mysql.com/doc/refman/8.4/en/limit-optimization.html
MySQL sometimes optimizes a query that has a LIMIT row_count clause and no HAVING clause: If you select only a few rows with LIMIT, MySQL uses indexes in some cases when normally it would prefer to do a full table scan. If the server uses temporary ... If you need only a specified number of rows from a result set, use a LIMIT clause in the query, rather than fetching the whole result set and throwing away the extra ...
https://dev.mysql.com/doc/refman/8.4/en/windows-restrictions.html
DATA DIRECTORY and INDEX DIRECTORY The DATA DIRECTORY clause of the CREATE TABLE statement is supported on Windows for InnoDB tables only, as described in Section 17.6.1.2, “Creating Tables Externally”. For MyISAM and other storage engines, the ...File system aliases When using MyISAM tables, you cannot use aliases within Windows link to the data files on another volume and then link back to the main MySQL datadir ... The following restrictions apply to use ...
https://dev.mysql.com/doc/internals/en/charsets.html
Character sets are recorded against individual tables and returned as part of the field data. You can obtain a list of the available character sets configured within a server by running SHOW COLLATION, or by running a query on the ... Character sets ...
https://dev.mysql.com/doc/internals/en/logging-transactions-definitions.html
Note: N-writes include updates to N-tables, but also CREATE and DROP statements. To reason about logging different table types, we make some preliminary definitions. (D-T-table) A table that has a transactional engine is called a T-table.
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replication-mta.html
Transaction Dependency and Writeset Handling Transaction dependencies are detected using analysis of each transaction's writeset, that is, the set of rows (table, key values) written by the transaction. Where a table has secondary unique keys, these ...To use this functionality with NDB Cluster, it is necessary that the replica be configured to use multiple worker ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replication-pitr.html
Performing point-in-time recovery of NDB Cluster tables with NDB Cluster and NDB Cluster Replication can be accomplished using a native NDB data backup (taken by issuing CREATE BACKUP in the ndb_mgm client) and restoring the ndb_binlog_index table ...At some later point, prior to restoring the cluster, make a backup of the mysql.ndb_binlog_index ... Point-in-time recovery—that is, recovery of data changes made since a given point in time—is ...
https://dev.mysql.com/doc/refman/8.4/en/select-optimization.html
Besides SELECT statements, the tuning techniques for queries also apply to constructs such as CREATE TABLE...AS SELECT, INSERT INTO...SELECT, and WHERE clauses in DELETE statements. Indexes are especially important for queries that reference ...
https://dev.mysql.com/doc/refman/8.4/en/server-option-variable-reference.html
The following table lists all command-line options, system variables, and status variables applicable within mysqld. The table lists command-line options (Cmd-line), options valid in configuration files (Option file), server system variables ...If ...