From: Tom Lane <tgl@sss.pgh.pa.us>
To: tschak <jochen.schlosser@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Index occupancy
Date: Sat, 04 Feb 2006 19:49:05 -0500
Message-ID: <5056.1139100545@sss.pgh.pa.us> (raw)
In-Reply-To: <1138888981.186497.321210@z14g2000cwz.googlegroups.com>
References: <1138888981.186497.321210@z14g2000cwz.googlegroups.com>
"tschak" <jochen.schlosser@gmail.com> writes:
> I have a question concerning the size of an index...
> What I acually did was bulid a btree index on an smallint attribute
> within a table with 10^8 rows. The table itself is app. 10GB large and
> what I would like to have the smallest possible indeces. Unfortunately
> the current size is about 2GB per indexed column (8 columns are indexed
> in total) which is too large if the planner is supposed to choose a
> bitmap scan between all of the indices.
> So what I would like to know is the following:
> Is there an easy way to tell postgres to occupy the index pages up to
> 100 %?
No, but even if there were it wouldn't make much of a difference. The
minimum possible size of a PG index is about 16 bytes per entry, which
would still put you at 1.6Gb for that many rows.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, jochen.schlosser@gmail.com
Subject: Re: Index occupancy
In-Reply-To: <5056.1139100545@sss.pgh.pa.us>
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