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[Gnumed-devel] backend listening

From: s j tan
Subject: [Gnumed-devel] backend listening
Date: Thu, 04 Sep 2003 23:32:18 +1000

What about keeping change sequence numbers on each table, and
incrementing with each change ? Then periodic polling by clients for
The changes they are interested in. The clients compare the max known
sequence number with the current sequence number on the
Database for the table in question, and if the server's is larger, then
the client has check all changes up to the server's sequence number.
The sequence numbers might also have an associated id field to identity
which rows changed.
This makes notification non-postgres dependent , as polling can be done
on any database. The period poller thread on each client
Will need to communicate with main client thread, possibly through a
synchronized access queue ( e.g. locks/ semaphore protected).

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