User's Manual

Chapter 6. Principles of SQL Remote Design
contains either a single value or a comma-separated list of values.
Not the subscriber list
Adaptive Server Enterprise does not enter into the log a list of subscribers.
The column value is entered. All handling of subscribers is left to the
Message Agent.
When a table is marked for replication using sp_add_remote_table (which
calls sp_setreplicate), Adaptive Server Enterprise places an entire before
image of the row in the transaction log for deletes, and entire after image for
inserts, and both images for updates. This means that the before and after
values of the subscription column are available.
Message Agent actions The Message Agent reads the evaluated subscription expressions or
subscription column entries from the transaction log, and matches the before
and after values against the subscription value for each subscriber to the
publication. In this way, the Message Agent can send the correct operations
to each subscriber.
While large numbers of subscribers do not have any impact on server
performance, they can impact Message Agent performance. Both the work
in matching subscription values against large numbers of subscription
values, and the work in sending the messages, can be demanding.
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