Oracle FAQ Your Portal to the Oracle Knowledge Grid

Home -> Community -> Mailing Lists -> Oracle-L -> Re: 8i updateable snapshots

Re: 8i updateable snapshots

From: A. Bardeen <abardeen1_at_YAHOO.COM>
Date: Sat, 20 Jul 2002 08:33:18 -0800
Message-ID: <>


The whole purpose of snapshots are to keep the snapshot data in sync with the master site, so the behavior you describe is normal.

What you've essentially done is a create a "writable" snapshot. You've made it updatable on the snapshot site, but you haven't finished the replication process so that the snapshot site can push its changes to the master site (because you don't want that to happen) by adding the snapshot to a snapshot group (not to be confused with a refresh group). So when you update the snapshot site, the updatable snapshot log (USLog$_) on the snapshot site is populated to ensure that these rows are in sync with the master site during the refresh. If you had fully completed the replication process, during the refresh those changes would have been pushed to the master site and then pulled back down as part of the refresh. Yes, we pull the same changes back down because conflict resolution is handled at the master site and the change may not have succeeded, but we *must* keep the snapshot in sync with its master table.

The replication triggers were internalized in 8.0 so there's no way to disable the trigger that populates the USLOG$ table... at least not in a supported fashion ;)

You're probably better off writing your own replication mechanism. If the volume of changes on the master table is small enough you can use a trigger to update the remote table. The two-phase commit process will definitely become a bottleneck, so with large volumes you should consider AQ (advanced queueing).

I haven't had a chance to look at Streams with 9.2, but that could very well offer the functionality you're seeking.


Do You Yahoo!?
Yahoo! Health - Feel better, live better
Please see the official ORACLE-L FAQ:
Author: A. Bardeen

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
To REMOVE yourself from this mailing list, send an E-Mail message
to: (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).
Received on Sat Jul 20 2002 - 11:33:18 CDT

Original text of this message