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Re: Nested xacts: looking for testers and review

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
Cc: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>,Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Nested xacts: looking for testers and review
Date: 2004-05-29 03:11:27
Message-ID: 200405290311.i4T3BRp14904@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Alvaro Herrera wrote:
> On Fri, May 28, 2004 at 05:43:41PM -0700, Stephan Szabo wrote:
> 
> > On Wed, 26 May 2004, Alvaro Herrera wrote:
> > 
> > > I have tested it and it passes all regression tests (including ones I
> > > added), plus some more tests I threw at it mainly for concurrency.
> > > Everything behaves as expected.  At this time I'd like to have it
> > > reviewed by the critic eye of the committers, and tested by whoever
> > > would be using it.
> > 
> > I unfortunately didn't really follow the discussions in the past (sorry :(
> > ), but are the transaction state modifying statements done in a
> > subtransaction supposed to live beyond subtransaction rollback?
> 
> Hmm, I suppose not.
> 
> I think this applies to all GUC variables, but I wonder if we want to
> save the value of each one at subtransaction start and recover it at
> abort?  Things could easily get huge.  Maybe only saving the ones that
> are different from the default value, and from the last saved value.

We have an on-commit field in the guc structures to handle
commit/rollback settings.  Do we need to extend that to subtransactions?

I don't think you can save off only the defaults in an efficient manner.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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