Re: [HACKERS] getting rid of SnapshotNow - Mailing list pgsql-odbc

From Alvaro Herrera
Subject Re: [HACKERS] getting rid of SnapshotNow
Date
Msg-id 20130719162932.GA4130@eldon.alvh.no-ip.org
Whole thread Raw
In response to Re: [HACKERS] getting rid of SnapshotNow  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: [HACKERS] getting rid of SnapshotNow  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-odbc
Robert Haas escribió:
> On Fri, Jul 19, 2013 at 1:27 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

> > Why not tell people to use SnapshotDirty if they need a
> > not-guaranteed-consistent result?  At least then it's pretty obvious
> > that you're getting some randomness in with your news.

> On further reflection, I think perhaps pgrowlocks should just register
> a fresh MVCC snapshot and use that.  Using SnapshotDirty would return
> TIDs of unseen tuples, which does not seem to be what is wanted there.

I think seeing otherwise invisible rows is useful in pgrowlocks.  It
helps observe the effects on tuples written by concurrent transactions
during experimentation.  But then, maybe this functionality belongs in
pageinspect instead.

--
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services


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