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https://dev.mysql.com/doc/refman/5.7/en/sys-schema-redundant-indexes.html
In the following column descriptions, the dominant index is the one that makes the redundant index redundant. The schema_redundant_indexes view has these columns: table_schema The schema that contains the table. The x$schema_flattened_keys view has ... The schema_redundant_indexes view displays indexes that duplicate other indexes or are made redundant by ...
https://dev.mysql.com/doc/refman/5.7/en/explain-extended.html
The Message value in SHOW WARNINGS output displays how the optimizer qualifies table and column names in the SELECT statement, what the SELECT looks like after the application of rewriting and optimization rules, and possibly other notes about the ... For SELECT statements, the EXPLAIN statement produces extra (“extended”) information that is not part of EXPLAIN output but can be viewed by issuing a SHOW WARNINGS statement following ...
https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-optimization-tips.html
Similarly, if your application computes a single result based on several column values or large volumes of data, combining the computation into a loadable function can help performance. If possible, classify reports as “live” or as ... This ...
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-option-tables.html
ndb-default-column-format: Use this value (FIXED or DYNAMIC) by default for COLUMN_FORMAT and ROW_FORMAT options when creating or adding table columns. ndb_default_column_format: Sets default row format and column format (FIXED or DYNAMIC) used for ... The following list includes command-line options, system variables, and status variables applicable within mysqld when it is running as an SQL node in an NDB ...
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-replication-issues.html
In older versions of NDB Cluster, operations that updated values of unique key columns of NDB tables could result in duplicate-key errors when replicated. NDB, unlike InnoDB or MyISAM, does not write changes to virtual columns to the binary log; ...
https://dev.mysql.com/doc/refman/5.7/en/optimizing-queries-myisam.html
For MyISAM tables that change frequently, try to avoid all variable-length columns (VARCHAR, BLOB, and TEXT). The table uses dynamic row format if it includes even a single variable-length column. The only cases where splitting up a table makes an ... Some general tips for speeding up queries on MyISAM tables: To help MySQL better optimize queries, use ANALYZE TABLE or run myisamchk --analyze on a table after it has been loaded with ...
https://dev.mysql.com/doc/refman/5.7/en/replication-features-invoked.html
For example, trying to replicate a loadable function with statement-based replication generates this warning because it currently cannot be determined by the MySQL server whether the function is deterministic. The ORIGINATOR column in the ...
https://dev.mysql.com/doc/refman/5.7/en/show-slave-hosts.html
Statement output includes this column only if the source server is started with the --show-slave-auth-info option. Statement output includes this column only if the source server is started with the --show-slave-auth-info option. A zero in this ...
https://dev.mysql.com/doc/refman/5.7/en/subquery-materialization.html
Materialization speeds up query execution by generating a subquery result as a temporary table, normally in memory. Assume that where_condition involves columns only from t2 and not t1 so that the subquery is noncorrelated. The optimizer uses ...
https://dev.mysql.com/doc/refman/5.7/en/subquery-optimization-with-exists.html
Table-condition generator: If the subquery is a join of several tables, the triggered condition is checked as soon as possible. In EXPLAIN output, the fallback shows up as Full scan on NULL key in the Extra column: mysql> EXPLAIN SELECT t1.col1, ...