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In this case, the UPDATE does not update anything.
♦ The row to be updated differs in one or more of its columns If one
of the values expected to be present has been changed by some other user,
an update conflict occurs.
At remote databases, the update takes place regardless of the values in the
row.
At the consolidated database, SQL Remote allows conflict resolution
operations to take place. Conflict resolution operations are held in a
trigger or stored procedure, and run automatically when a conflict is
detected.
In Adaptive Server Anywhere, the conflict resolution trigger runs before
the update, and the update proceeds when the trigger is finished. In
Adaptive Server Enterprise, the conflict resolution procedure runs after
the update has been applied.
♦ A table without a primary key or uniqueness constraint refers to all
columns in the WHERE clause of replicated updates When two
users update the same row, replicated updates will not update anything
and databases will become inconsistent. All replicated tables should have
a primary key or uniqueness constraint and the columns in the constraint
should never be updated.
Replication of procedures
Any replication system is faced with a choice between two options when
replicating a stored procedure call:
♦ Replicate the procedure call A corresponding procedure is executed at
the replicate site, or
♦ Replicate the procedure actions The individual actions (INSERTs,
UPDATEs, DELETEs and so on) of the procedure are replicated.
SQL Remote replicates procedures by replicating the actions of a procedure.
The procedure call is not replicated.
Replication of triggers
Trigger replication in SQL Remote is different for the Adaptive Server
Enterprise Message Agent and the Adaptive Server Anywhere Message
Agent.
Trigger replication from
Adaptive Server
Enterprise
From Adaptive Server Enterprise, trigger actions are replicated. You must
ensure that triggers are not fired in the remote Adaptive Server Anywhere
databases. If the trigger were fired, its actions would be executed twice.
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