User's Manual

Chapter 12. Administering SQL Remote for Adaptive Server
Enterprise
System Administration Guide .
Replicating only
backed-up transactions
The Message Agent also provides a command-line option (-u) that only
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 -u command-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 -u command-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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