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https://dev.mysql.com/doc/refman/8.0/en/hash-joins.html
Prior to MySQL 8.0.20, a hash join could not be used if any pair of joined tables did not have at least one equi-join condition, and the slower block nested loop algorithm was employed. This means that the types of queries which can be optimized ...
https://dev.mysql.com/doc/refman/8.0/en/index-hints.html
For example, the following two queries are equivalent: SELECT * FROM t1 USE INDEX (i1) IGNORE INDEX (i2) USE INDEX (i2); SELECT * FROM t1 USE INDEX (i1); For FULLTEXT searches, index hints work as follows: For natural language mode searches, index ... Index hints give the optimizer information about how to choose indexes during query ...
https://dev.mysql.com/doc/refman/8.0/en/index-merge-optimization.html
The Index Merge access method retrieves rows with multiple range scans and merges their results into one. This access method merges index scans from a single table only, not scans across multiple tables. The merge can produce unions, intersections, ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-information-schema-files-table.html
The Information Schema FILES table provides metadata about all InnoDB tablespace types including file-per-table tablespaces, general tablespaces, the system tablespace, temporary table tablespaces, and undo tablespaces (if present). For more ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-information-schema-fulltext_index-tables.html
INNODB_FT_BEING_DELETED: Provides a snapshot of the INNODB_FT_DELETED table; it is used only during an OPTIMIZE TABLE maintenance operation. When OPTIMIZE TABLE is run, the INNODB_FT_BEING_DELETED table is emptied, and DOC_ID values are removed from ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-memcached-benefits.html
Data requested through the memcached protocol is transparently queried from an InnoDB table, without going through the MySQL SQL layer. You can access the underlying InnoDB table through SQL for reporting, analysis, ad hoc queries, bulk loading, ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-performance-schema.html
This section provides a brief introduction to InnoDB integration with Performance Schema. For comprehensive Performance Schema documentation, see Chapter 29, MySQL Performance Schema. You can profile certain internal InnoDB operations using the ...
https://dev.mysql.com/doc/refman/8.0/en/optimize-character.html
If a table contains string columns such as name and address, but many queries do not retrieve those columns, consider splitting the string columns into a separate table and using join queries with a foreign key when necessary. Such compact tables ...
https://dev.mysql.com/doc/refman/8.0/en/outer-join-optimization.html
MySQL implements an A LEFT JOIN B join_specification as follows: Table B is set to depend on table A and all tables on which A depends. Table A is set to depend on all tables (except B) that are used in the LEFT JOIN condition. The LEFT JOIN ...
https://dev.mysql.com/doc/refman/8.0/en/partitioning-columns-range.html
The SELECT statement in the preceding example could also have been written using explicit row constructors, like this: SELECT ROW(5,10) < ROW(5,12), ROW(5,11) < ROW(5,12), ROW(5,12) < ROW(5,12); For more information about the use of row constructors ... Range columns partitioning is similar to range partitioning, but enables you to define partitions using ranges based on multiple column ...