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I agree, using indexes as a "skinny" table is a whole other feature that would be nice.
--
Chad
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Re: Querying distinct values from a large table
- From: "Chad Wagner" <chad(dot)wagner(at)gmail(dot)com>
- To: "Luke Lonergan" <llonergan(at)greenplum(dot)com>
- Cc: "Simon Riggs" <simon(at)2ndquadrant(dot)com>, "Igor Lobanov" <ilobanov(at)swsoft(dot)com>, "Richard Huxton" <dev(at)archonet(dot)com>, pgsql-performance(at)postgresql(dot)org
- Subject: Re: Querying distinct values from a large table
- Date: Tue, 30 Jan 2007 10:03:03 -0500
On 1/30/07, Luke Lonergan <llonergan(at)greenplum(dot)com> wrote:
Was that integrated back into PostgreSQL, or is that part of Greenplum's offering?
Not that it helps Igor, but we've implemented single pass sort/unique,
grouping and limit optimizations and it speeds things up to a single seqscan
over the data, from 2-5 times faster than a typical external sort.
Was that integrated back into PostgreSQL, or is that part of Greenplum's offering?
I can't think of a way that indexing would help this situation given the
required visibility check of each tuple.
I agree, using indexes as a "skinny" table is a whole other feature that would be nice.
--
Chad
http://www.postgresqlforums.com/
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