Sybase DC38133-01-0902-01 manual Stable queue recovery issues, Transaction log management

	Chapter 12. Administering SQL Remote for Adaptive Server
	Enterprise
	System Administration Guide.
Replicating only	The Message Agent also provides a command-line option (-u) that only
backed-up transactions	sends transactions that have been backup up. In Adaptive Server Enterprise,
	this means transactions complete before the latest dump database command
	or dump transaction command.
Choosing an approach	The goal of the strategy is to reduce the possibility of requiring re-extraction
	of remote databases to an acceptable level. In large setups, the possibility
	must be as close to zero as possible, as the cost of re-extraction (in terms of
	down time) is very high.
	♦ The Message Agent -ucommand-line option can be used instead of
	transaction log mirroring when recovery of all transactions in a
	consolidated database is not needed and mirroring is considered too
	expensive. This may be true in small setups or setups where there are no
	local users on the consolidated database.
	♦ The Message Agent -ucommand-line option can also be used in addition
	to mirroring to provide additional protection against total site failure or
	double media failure.

Stable queue recovery issues

Keeping the stable queue in a separate database complicates backup and recovery, as consistent versions of the two databases have to be recovered.

Normal recovery automatically restores the two databases to a consistent state, but recovery from media failure takes some care. When restoring database dumps and transaction dumps, it is important to recover the stable queue to a consistent point.

Two procedures in the stable store database are provided to help with recovery from media failure:

♦sp_queue_dump_database This procedure is called whenever a dump database is scanned from the transaction log.

♦sp_queue_dump_transaction This procedure is called whenever a dump transaction is scanned from the transaction log.

You can modify these stored procedures to issue dump database and dump transaction commands in the stable store database.

Transaction log management

The Adaptive Server Enterprise log transfer interface allows the Message

Agent to scan the Adaptive Server Enterprise transaction log. When this

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