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https://dev.mysql.com/doc/refman/9.7/en/group-by-optimization.html
The most important preconditions for using indexes for GROUP BY are that all GROUP BY columns reference attributes from the same index, and that the index stores its keys in order (as is true, for example, for a BTREE index, but not for a HASH ...
https://dev.mysql.com/doc/refman/9.7/en/group-replication-communication-protocol.html
MySQL 8.0.27 and later also allow the group communication engine to operate with a single consensus leader when the group is in single-primary mode and group_replication_paxos_single_leader is set to true (see Section 20.7.3, “Single Consensus ...
https://dev.mysql.com/doc/refman/9.7/en/group-replication-failure-detection.html
If the group’s consensus is that the suspicion is probably true, the group takes a coordinated decision to expel the member. Group Replication’s failure detection mechanism is a distributed service which is able to identify that a server in the ...
https://dev.mysql.com/doc/refman/9.7/en/gtid-functions.html
GTID_SUBSET(set1,set2) Given two sets of global transaction identifiers set1 and set2, returns true if all GTIDs in set1 are also in set2. The functions described in this section are used with GTID-based replication. It is important to keep in mind ...
https://dev.mysql.com/doc/refman/9.7/en/handler.html
This occurs when both of the following circumstances are true: Any session executes FLUSH TABLES or DDL statements on the handler's table. HANDLER tbl_name OPEN [ [AS] alias] HANDLER tbl_name READ index_name { = | <= | >= | < | > } ...
https://dev.mysql.com/doc/refman/9.7/en/identifier-mapping.html
The same is true for any use of $ (dollar sign) in a schema or table name; it is replaced with @0024 on the filesystem. There is a correspondence between database and table identifiers and names in the file system. For the basic structure, MySQL ...
https://dev.mysql.com/doc/refman/9.7/en/if.html
If a given search_condition evaluates to true, the corresponding THEN or ELSEIF clause statement_list executes. [ELSE statement_list] END IF The IF statement for stored programs implements a basic conditional construct. Note There is also an IF() ...
https://dev.mysql.com/doc/refman/9.7/en/index-hints.html
This is true even if the hint is given for a non-FULLTEXT index. Index hints give the optimizer information about how to choose indexes during query processing. Index hints, described here, differ from optimizer hints, described in Section 10.9.3, ...
https://dev.mysql.com/doc/refman/9.7/en/information-schema-parameters-table.html
The return value is not a true parameter, so the row that describes it has these unique characteristics: The ORDINAL_POSITION value is 0. The PARAMETERS table provides information about parameters for stored routines (stored procedures and stored ...
https://dev.mysql.com/doc/refman/9.7/en/information-schema-tables-table.html
(This is also true if the InnoDB table is partitioned.) AVG_ROW_LENGTH The average row length. The information_schema_stats_expiry system variable defines the period of time before cached table statistics expire. If there are no cached statistics or ...