Sybase DC38133-01-0902-01 manual Synchronizing data over a message system

Synchronizing data over a message system

Creating subscriptions	A subscription is created at a consolidated Adaptive Server Enterprise
	database using the sp_subscription procedure with a first argument of
	create.
	Creating a subscription defines the data to be received. It does not
	synchronize a subscription (provide an initial copy of the data) or start
	(exchange messages) a subscription.
Synchronizing	Synchronizing a subscription causes the Message Agent to send a copy of all
subscriptions	rows in the subscription to the subscriber. It assumes that an appropriate
	database schema is in place. At an Adaptive Server Anywhere consolidated
	database, subscriptions are synchronized using the SYNCHRONIZE
	SUBSCRIPTION statement. At an Adaptive Server Enterprise consolidated
	database, subscriptions are synchronized using the sp_subscription
	procedure with a first argument of synchronize.
	When synchronization messages are received at a subscriber database, the
	Message Agent replaces the current contents of the database with the new
	copy. Any data at the subscriber that is part of the subscription, and which
	has not been replicated to the consolidated database, is lost. Once
	synchronization is complete, the subscription is started by the Message
	Agent using the START SUBSCRIPTION statement or sp_subscription
	procedure with a first argument of start.
	Large volume of messages may result
	Synchronizing databases over a message system may lead to large volumes
	of messages. In many cases, it is preferable to use the extraction process to
	synchronize a database locally without placing this burden on the message
	system.
Synchronizing	If a remote database becomes out of step with the consolidated database, and
subscriptions during	cannot be brought back in step using the SQL passthrough capabilities of
operation	SQL Remote, synchronizing the subscription forces the remote database into
	step with the consolidated database by copying the rows of the subscription
	from the consolidated database over the contents at the remote database.
	Data loss on synchronization
	Any data in the remote database that is part of the subscription, but which
	has not been replicated to the consolidated database, is lost when the
	subscription is synchronized. You may wish to unload or back up the
	remote database using Sybase Central or, for Adaptive Server Anywhere,
	the dbunload utility before synchronizing the database.

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