[AMQ-1244] DatabaseLocker implementation impedes database replication

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.1.1
• Fix Version/s: 5.2.0
• Component/s: Message Store

Environment

Latest ActiveMQ snapshot, Sybase ASE 12.5.x

• Assignee: Robert Davies
• Reporter: Marcos Sanz
• Created: 11/May/07 06:33
• Updated: 19/Jun/08 22:45
• Resolved: 19/Jun/08 22:45

Description

The current implementation of the JDBC Master/Slave feature makes one broker (the master) acquire a lock on a database object. In Sybase, this has been implemented with the command:

LOCK TABLE foo IN EXCLUSIVE MODE

This command can only be executed within a transaction, see:
http://manuals.sybase.com/onlinebooks/group-as/asg1250e/sqlug/@Generic__BookTextView/54552;pt=54651

This implies that for the whole lifespan of the ActiveMQ-process there is an open transaction in the RDBMS. This is a problem in a professional environment making use of a database replication server: The open transaction impedes that the transaction log in the active database is emptied, then the stable queue at the replication server won't be purged and will steadily grow up to infinitum. We have been able to observe this behaviour.