Contents Index Tracking messages by transaction log offsets Administering SQL Remote for Adaptive Server Anywhere

SQL Remote User's Guide
  SQL Remote Administration
    The message tracking system

Handling of lost or corrupt messages


When messages are received at a subscriber database, the Message Agent applies them in the correct order (determined from the log offsets) and sends confirmation to the publisher. If a message is missing, the Message Agent increments the local value of rereceive_count, and requests that it be resent. Other messages present or en route are not applied.

The request from a subscriber to resend a message increments the resend_count value at the publisher database, and also sets the publisher's log_sent value to the value of confirm_sent. This resetting of the log_sent value causes operations to be resent.

Users cannot reset log_sent 
The log_sent value cannot be reset by a user, as it is in a system table.
Message identification 

Each message is identified by three values:

Messages with a resend_count value smaller than rereceive_count are not applied; they are deleted. This ensures that operations are not applied more than once.


Contents Index Tracking messages by transaction log offsets Administering SQL Remote for Adaptive Server Anywhere