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Re: R: R: space taken by a row & compressed data

From: Greg Stark <gsstark(at)mit(dot)edu>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: R: R: space taken by a row & compressed data
Date: 2004-08-26 20:13:03
Message-ID: 87d61dpsj4.fsf@stark.xeocode.com (view raw or flat)
Thread:
Lists: pgsql-general
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> "Leonardo Francalanci" <lfrancalanci(at)simtel(dot)ie> writes:
> > Could you point me to some docs on this TOAST-mechanism?
> > For instance: what kind of method is used to compress data?
> 
> When in doubt, read the code ;-)
> src/backend/utils/adt/pg_lzcompress.c
> src/include/utils/pg_lzcompress.h

Are toasted values stored in the table itself or in a separate table?

My understanding was that it was the latter, which leads me to wonder whether
he'll actually gain anything by having all the records in his table be
toasted. It'll mean every record lookup has to traverse two indexes, and a
sequential scan loses the sequential read performance boost.

Or am I wrong and toasted values can be stored inline?

-- 
greg


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