From: Gregory Stark <gsstark@mit.edu>
To: Alvaro Herrera <alvherre@commandprompt.com>
Cc: Gregory Stark <gsstark@mit.edu>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Matteo Sgalaberni <sgala@sgala.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: database bloat, non removovable rows, slow query etc... [RESOLVED]
Date: 04 Sep 2006 20:30:15 -0400
Message-ID: <878xkz17fs.fsf@stark.xeocode.com> (raw)
In-Reply-To: <20060904224716.GB14107@alvh.no-ip.org>
References: <20060901123915.GT2266@sgala.com>
<4027.1157121810@sss.pgh.pa.us>
<20060901172829.GX2266@sgala.com>
<12756.1157132120@sss.pgh.pa.us>
<20060902083725.GB2266@sgala.com>
<2191.1157206883@sss.pgh.pa.us>
<87ejur1drl.fsf@stark.xeocode.com>
<20060904224716.GB14107@alvh.no-ip.org>
Alvaro Herrera <alvherre@commandprompt.com> writes:
> Gregory Stark wrote:
> > Tom Lane <tgl@sss.pgh.pa.us> writes:
> >
> > > Matteo Sgalaberni <sgala@sgala.com> writes:
> > > > Good to know this...but why this behaviour? it'is lovely...:)
> > >
> > > Open transactions are tracked across the whole cluster. This is
> > > necessary when vacuuming shared catalogs. In principle we could
> > > track per-database xmin values as well, but the distributed overhead
> > > that'd be added to *every* GetSnapshotData call is a bit worrisome.
> >
> > Don't we do that now in CVS (ie, in 8.2)?
>
> No, we don't.
I must be misunderstanding Tom's comment then.
What I'm referring to is lazy_vacuum_rel() calls vacuum_set_xid_limits with
the relisshared flag of the relation. vacuum_set_xid_limits passes that to
GetOldestXmin as the allDbs parameter. GetOldestXmin ignores transactions not
connected to the same database unless allDbs is true.
--
greg
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To: pgsql-performance@postgresql.org
Cc: gsstark@mit.edu, alvherre@commandprompt.com, tgl@sss.pgh.pa.us, sgala@sgala.com
Subject: Re: database bloat, non removovable rows, slow query etc... [RESOLVED]
In-Reply-To: <878xkz17fs.fsf@stark.xeocode.com>
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