From: Tom Lane <tgl@sss.pgh.pa.us>
To: Heikki Linnakangas <heikki@enterprisedb.com>
Cc: Jim C. Nasby <jim@nasby.net>
Cc: ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp>
Cc: pgsql-hackers@postgresql.org
Subject: Re: Dead Space Map version 2
Date: Wed, 28 Feb 2007 00:34:51 -0500
Message-ID: <25502.1172640891@sss.pgh.pa.us> (raw)
In-Reply-To: <45E3FF0D.2050104@enterprisedb.com>
References: <20070227113655.6381.ITAGAKI.TAKAHIRO@oss.ntt.co.jp>
<20070227051144.GK29041@nasby.net>
<12631.1172555721@sss.pgh.pa.us>
<45E3FF0D.2050104@enterprisedb.com>
Heikki Linnakangas <heikki@enterprisedb.com> writes:
> Tom Lane wrote:
>> I'd be happier if the DSM content could be
>> treated as just a hint.
> If we don't have a frozen state, we can't use the DSM to implement
> index-only scans.
To implement index-only scans, the DSM would have to be expected to
provide 100% reliable coverage, which will increase its cost and
complexity by orders of magnitude. If you insist on that, I will bet
you lunch at a fine restaurant that it doesn't make it into 8.3.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, heikki@enterprisedb.com, jim@nasby.net, itagaki.takahiro@oss.ntt.co.jp, pgsql-hackers@postgresql.org
Subject: Re: Dead Space Map version 2
In-Reply-To: <25502.1172640891@sss.pgh.pa.us>
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