From: Amit Kapila <amit.kapila@huawei.com>
To: "'Josh Berkus'" <josh@agliodbs.com>, <pgsql-hackers@postgresql.org>
References: <20130109230731.GA30885@momjian.us>
 <50EE0D8C.3080602@agliodbs.com>
In-Reply-To: <50EE0D8C.3080602@agliodbs.com>
Subject: Re: 9.2.1 & index-only scans : abnormal heap fetches after VACUUM
 FULL
Date: Thu, 10 Jan 2013 11:45:47 +0530
Message-ID: <006901cdeef9$eefd56a0$ccf803e0$@kapila@huawei.com>
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On Thursday, January 10, 2013 6:09 AM Josh Berkus wrote:
> On 01/09/2013 03:07 PM, Bruce Momjian wrote:
> > How do we want to handle the case where VACUUM FULL clears the
> > visibility map, causing loss of index-only scans?
> >
> > 	http://archives.postgresql.org/pgsql-performance/2012-
> 11/msg00317.php
> >
> > Do we document this behavior or add a TODO item?
> >
>=20
> Both?
>=20
> Surely VACUUM FULL should rebuild the visibility map, and make tuples
> in
> the new relation all-visible, no?

I think it cannot made all visible.
How about if any transaction in SSI mode is started before Vacuum Full, sho=
uld it see all tuples.

With Regards,
Amit Kapila.


--=20
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