Re: sql trace - XCTEND rlbk=1, rd_only=1

From: Boris Dali <boris_dali_at_yahoo.ca>
Date: Tue, 25 Nov 2003 14:14:27 -0800
Message-ID: <F001.005D7CC3.20031125141427@fatcity.com>

Thanks, Jared, Tanel.

I was a little supprised to see a combination rlbk=1,rd_only=1. Why read-only bit is set here if it rolls back anyway?
So I thought may be they mark their tx explicitly as read-only (aka "set transaction read-only"). Reveiwing OCI fine manual there seemed to be an option of doing just that with the OCITransStart() call and setting some flags...

But than simple test-case of tracing commit and rollback in SQL*Plus disproved the theory about read-only tx, as "normal" commit/rollback produce this combination regardless of the tx type:

commit - XCTEND rlbk=0, rd_only=1
rollback - XCTEND rlbk=1, rd_only=1

set transaction read only

commit - XCTEND rlbk=0, rd_only=1
rollback - XCTEND rlbk=1, rd_only=1

So much for my theory :-(

Another question I had here is whether or not having so many (implicit?) rollbacks on about every SELECT statement all over my trace file bears any overhead and proves deficiency of a stateless architecture used by this application - but again reviewing v$sesstat before and after I see user rollbacks count incremented, but no additional redo vectors generated. I guess I can try Tom Kyte's test harness, but it just doesn't sit well with me that 30 selects are as cheap as 30 selects with 30 rollbacks.

Thanks,
Boris Dali.

---

Post your free ad now! http://personals.yahoo.ca
--

Please see the official ORACLE-L FAQ: http://www.orafaq.net
--

Author: Boris Dali
  INET: boris_dali_at_yahoo.ca

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------

To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (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 Tue Nov 25 2003 - 16:14:27 CST