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https://dev.mysql.com/doc/refman/8.0/en/query-log.html
mysqld writes statements to the query log in the order that it receives them, which might differ from the order in which they are executed. This logging order is in contrast with that of the binary log, for which statements are written after they ...
https://dev.mysql.com/doc/refman/8.0/en/replication-features-limit.html
SELECT statements is unsafe since the order of the rows affected is not defined. (Such statements can be replicated correctly with statement-based replication only if they also contain an ORDER BY clause.) When such a statement is encountered: When ... Statement-based replication of LIMIT clauses in DELETE, UPDATE, and INSERT ...
https://dev.mysql.com/doc/refman/8.0/en/replication-gtids-assign-anon.html
On a multi-threaded replica, this means the order of the GTIDs does not necessarily match the order of the transactions, even if slave-preserve-commit-order=1 is set. From MySQL 8.0.23, you can set up replication channels to assign a GTID to ...
https://dev.mysql.com/doc/refman/8.0/en/replication-gtids-concepts.html
The transaction_id is a sequence number determined by the order in which the transaction was committed on the source. This example shows the GTID set stored in the gtid_executed system variable (@@GLOBAL.gtid_executed) of a replica that has applied ... A global transaction identifier (GTID) is a unique identifier created and associated with each transaction committed on the server of origin (the ...
https://dev.mysql.com/doc/refman/8.0/en/replication-gtids-functions.html
Example 19.3 Selecting the most up-to-date replica for manual failover The stored function GTID_UNION() can be used to identify the most up-to-date replica from a set of replicas, in order to perform a manual failover operation after a source server ... This section provides examples of stored functions (see Chapter 27, Stored Objects) which you can create using some of the built-in functions provided by MySQL for use with GTID-based replication, listed here: GTID_SUBSET(): Shows whether one GTID set is a subset of ...
https://dev.mysql.com/doc/refman/8.0/en/replication-gtids-lifecycle.html
The replica verifies that no thread has yet taken ownership of the GTID in gtid_next in order to process the transaction. On a multithreaded replica (with replica_parallel_workers > 0 or slave_parallel_workers > 0 ), transactions can be applied in ... The life cycle of a GTID consists of the following steps: A transaction is executed and committed on the ...
https://dev.mysql.com/doc/refman/8.0/en/replication-options-reference.html
replica_preserve_commit_order: Ensures that all commits by replica workers happen in same order as on source to maintain consistency when using parallel applier threads. slave_preserve_commit_order: Ensures that all commits by replica workers happen ... The following two sections provide basic information about the MySQL command-line options and system variables applicable to replication and the binary ...
https://dev.mysql.com/doc/refman/8.0/en/semijoins.html
An ORDER BY clause is permitted but ignored, since ordering is irrelevant to the evaluation of semijoin strategies. A semijoin is a preparation-time transformation that enables multiple execution strategies such as table pullout, duplicate weedout, ...
https://dev.mysql.com/doc/refman/8.0/en/slow-query-log.html
mysqld writes a statement to the slow query log after it has been executed and after all locks have been released, so log order might differ from execution order. The server uses the controlling parameters in the following order to determine whether ... The slow query log consists of SQL statements that take more than long_query_time seconds to execute and require at least min_examined_row_limit rows to be ...
https://dev.mysql.com/doc/refman/8.0/en/working-with-null.html
When doing an ORDER BY, NULL values are presented first if you do ORDER BY ... The NULL value can be surprising until you get used to it. Conceptually, NULL means “a missing unknown value” and it is treated somewhat differently from other ...