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SQL Anywhere 12.0.0 (Français) » SQL Remote » Managing SQL Remote systems » Understanding the Guaranteed Message Delivery System

 

Ensuring that operations are applied in the correct order

To ensure that the replicated statements are applied in the correct order, the Guaranteed Message Delivery System uses the transaction log offsets of the publisher and subscriber databases. Each COMMIT is marked in the transaction log by a well-defined offset. The order of transactions can be determined by comparing their transaction log offset values.

Each message includes the following transaction log offsets:

  • The transaction log offset of the last COMMIT in the previous message. If a transaction spans several messages, there is a sequence number within the transaction to order the messages correctly. Ensuring that operations are applied in the correct order.

  • The transaction log offset of the last COMMIT in the message.

 Message ordering
 Sending messages
 Receiving messages
 See also