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https://dev.mysql.com/doc/refman/5.7/en/distinct-optimization.html
Thus, for more details on the optimization possibilities for DISTINCT queries, see Section 8.2.1.15, “GROUP BY Optimization”. DISTINCT combined with ORDER BY needs a temporary table in many cases. Because DISTINCT may use GROUP BY, learn how ...
https://dev.mysql.com/doc/refman/5.7/en/faqs-mysql-cluster.html
How do I continue to send queries in the event that one of the SQL nodes fails? A.10.40. However, it also means that queries that could otherwise use range scans must be satisfied by other means, which can result in slower selects. How do I continue ... In the following section, we answer questions that are frequently asked about NDB Cluster and the NDB storage ...
https://dev.mysql.com/doc/refman/5.7/en/faqs-thread-pool.html
This minimizes the overhead and expense of establishing and tearing down connections as queries are submitted to the MySQL server. By contrast, the Thread Pool operates on the MySQL server side and is designed to manage the execution of inbound ...
https://dev.mysql.com/doc/refman/5.7/en/group-replication-bootstrap.html
The process of starting a group for the first time is called bootstrapping. The bootstrap should only be done by a single server, the one that starts the group and only once. This is why the value of the group_replication_bootstrap_group option was ...
https://dev.mysql.com/doc/refman/5.7/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/5.7/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/5.7/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). Note The ...
https://dev.mysql.com/doc/refman/5.7/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/5.7/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/5.7/en/innodb-online-ddl-operations.html
Concurrent queries are permitted for tables partitioned by HASH or LIST. Concurrent queries are permitted for tables partitioned by HASH or LIST, as MySQL copies the data while holding a shared lock. Concurrent queries are permitted for tables ...