MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0

24.7 Stored Program Binary Logging

The binary log contains information about SQL statements that modify database contents. This information is stored in the form of events that describe the modifications. (Binary log events differ from scheduled event stored objects.) The binary log has two important purposes:

However, if logging occurs at the statement level, there are certain binary logging issues with respect to stored programs (stored procedures and functions, triggers, and events):

This section describes how MySQL handles binary logging for stored programs. It states the current conditions that the implementation places on the use of stored programs, and what you can do to avoid logging problems. It also provides additional information about the reasons for these conditions.

In general, the issues described here result when binary logging occurs at the SQL statement level (statement-based binary logging). If you use row-based binary logging, the log contains changes made to individual rows as a result of executing SQL statements. When routines or triggers execute, row changes are logged, not the statements that make the changes. For stored procedures, this means that the CALL statement is not logged. For stored functions, row changes made within the function are logged, not the function invocation. For triggers, row changes made by the trigger are logged. On the slave side, only the row changes are seen, not the stored program invocation.

Mixed format binary logging (binlog_format=MIXED) uses statement-based binary logging, except for cases where only row-based binary logging is guaranteed to lead to proper results. With mixed format, when a stored function, stored procedure, trigger, event, or prepared statement contains anything that is not safe for statement-based binary logging, the entire statement is marked as unsafe and logged in row format. The statements used to create and drop procedures, functions, triggers, and events are always safe, and are logged in statement format. For more information about row-based, mixed, and statement-based logging, and how safe and unsafe statements are determined, see Section 17.2.1, “Replication Formats”.

Unless noted otherwise, the remarks here assume that binary logging is enabled on the server (see Section 5.4.4, “The Binary Log”.) If the binary log is not enabled, replication is not possible, nor is the binary log available for data recovery.

The conditions on the use of stored functions in MySQL can be summarized as follows. These conditions do not apply to stored procedures or Event Scheduler events and they do not apply unless binary logging is enabled.

Triggers are similar to stored functions, so the preceding remarks regarding functions also apply to triggers with the following exception: CREATE TRIGGER does not have an optional DETERMINISTIC characteristic, so triggers are assumed to be always deterministic. However, this assumption might be invalid in some cases. For example, the UUID() function is nondeterministic (and does not replicate). Be careful about using such functions in triggers.

Triggers can update tables, so error messages similar to those for stored functions occur with CREATE TRIGGER if you do not have the required privileges. On the slave side, the slave uses the trigger DEFINER attribute to determine which user is considered to be the creator of the trigger.

The rest of this section provides additional detail about the logging implementation and its implications. You need not read it unless you are interested in the background on the rationale for the current logging-related conditions on stored routine use. This discussion applies only for statement-based logging, and not for row-based logging, with the exception of the first item: CREATE and DROP statements are logged as statements regardless of the logging mode.