Do MySQL 5.0 stored procedures and functions work with replication?
Yes, standard actions carried out in stored procedures and functions are replicated from a master MySQL server to a slave server. There are a few limitations that are described in detail in Section 17.4, “Binary Logging of Stored Routines and Triggers”.
Are stored procedures and functions created on a master server replicated to a slave?
Yes, creation of stored procedures and functions carried out
through normal DDL statements on a master server are
replicated to a slave, so the objects will exist on both
statements for stored procedures and functions are also
How are actions that take place inside stored procedures and functions replicated?
MySQL records each DML event that occurs in a stored procedure and replicates those individual actions to a slave server. The actual calls made to execute stored procedures are not replicated.
Stored functions that change data are logged as function invocations, not as the DML events that occur inside each function.
Are there special security requirements for using stored procedures and functions together with replication?
Yes. Because a slave server has authority to execute any statement read from a master's binary log, special security constraints exist for using stored functions with replication. If replication or binary logging in general (for the purpose of point-in-time recovery) is active, then MySQL DBAs have two security options open to them:
Any user wishing to create stored functions must be
Alternatively, a DBA can set the
variable to 1, which enables anyone with the standard
CREATE ROUTINE privilege to create
Note: Before MySQL 5.0.16, these restrictions also apply to
stored procedures and the system variable is named
What limitations exist for replicating stored procedure and function actions?
Non-deterministic (random) or time-based actions embedded in
stored procedures may not replicate properly. By their very
nature, randomly produced results are not predictable and
cannot be exactly reproduced, and therefore, random actions
replicated to a slave will not mirror those performed on a
master. Note that declaring stored functions to be
DETERMINISTIC or setting the
variable to 0 will not allow random-valued operations to be
In addition, time-based actions cannot be reproduced on a slave because the timing of such actions in a stored procedure is not reproducible through the binary log used for replication. It records only DML events and does not factor in timing constraints.
Finally, non-transactional tables for which errors occur
during large DML actions (such as bulk inserts) may experience
replication issues in that a master may be partially updated
from DML activity, but no updates are done to the slave
because of the errors that occurred. A workaround is for a
function's DML actions to be carried out with the
IGNORE keyword so that updates on the
master that cause errors are ignored and updates that do not
cause errors are replicated to the slave.
Do the preceding limitations affect MySQL's ability to do point-in-time recovery?
The same limitations that affect replication do affect point-in-time recovery.
What will MySQL do to correct the aforementioned limitations?
A future release of MySQL is expected to feature a choice in how replication should be handled:
Statement-based replication (current implementation).
Row-level replication (that will solve all the limitations described earlier).
Do triggers work with replication?
Triggers and replication in MySQL 5.0 work the same as in most other database engines: Actions carried out through triggers on a master are not replicated to a slave server. Instead, triggers that exist on tables that reside on a MySQL master server need to be created on the corresponding tables on any MySQL slave servers so that the triggers activate on the slaves as well as the master.
How are actions carried out through triggers on a master replicated to a slave?
First, the triggers that exist on a master must be re-created
on the slave server. Once this is done, the replication flow
works as any other standard DML statement that participates in
replication. For example, consider a table
EMP that has an
insert trigger, which exists on a master MySQL server. The
EMP table and
insert trigger exist on the slave server as well. The
replication flow would be:
INSERT statement is made to
AFTER trigger on
INSERT statement is written to the
The replication slave picks up the
INSERT statement to
EMP and executes it.
AFTER trigger on
EMP that exists on the slave activates.