From: Tom Lane <tgl@sss.pgh.pa.us>
To: Greg Stark <gsstark@mit.edu>
Cc: Dirk Lutzebaeck <lutzeb@aeccom.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: query produces 1 GB temp file
Date: Sat, 05 Feb 2005 18:01:03 -0500
Message-ID: <190.1107644463@sss.pgh.pa.us> (raw)
In-Reply-To: <87mzuik4ey.fsf@stark.xeocode.com>
References: <20050205182117.0125074@mail2.aeccom.com>
<87y8e2kb8j.fsf@stark.xeocode.com>
<29929.1107643284@sss.pgh.pa.us>
<87mzuik4ey.fsf@stark.xeocode.com>
Greg Stark <gsstark@mit.edu> writes:
> Am I wrong? I thought the disk sort algorithm was the polyphase tape sort from
> Knuth which is always reading two tapes and writing to a third.
It is a polyphase sort, but we recycle the input "tapes" as fast as we
use them, so that the maximum disk space usage is about as much as the
data volume to sort.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, gsstark@mit.edu, lutzeb@aeccom.com
Subject: Re: query produces 1 GB temp file
In-Reply-To: <190.1107644463@sss.pgh.pa.us>
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