From: Stephan Szabo <sszabo@megazone.bigpanda.com>
To: Thomas F.O'Connell <tfo@sitening.com>
Cc: PgSQL - SQL <pgsql-sql@postgresql.org>
Subject: Re: Counting Distinct Records
Date: Wed, 17 Nov 2004 06:52:54 -0800 (PST)
Message-ID: <20041117064813.V17486@megazone.bigpanda.com> (raw)
In-Reply-To: <A72D6B26-3823-11D9-95C2-000D93AE0944@sitening.com>
References: <1B2F7B00-3808-11D9-95C2-000D93AE0944@sitening.com>
<20041116115807.E79990@megazone.bigpanda.com>
<6E79C2FE-380B-11D9-95C2-000D93AE0944@sitening.com>
<20041116141911.K84773@megazone.bigpanda.com>
<A72D6B26-3823-11D9-95C2-000D93AE0944@sitening.com>
On Tue, 16 Nov 2004, Thomas F.O'Connell wrote:
> Hmm. I was more interested in using COUNT( * ) than DISTINCT *.
>
> I want a count of all rows, but I want to be able to specify which
> columns are distinct.
I'm now a bit confused about exactly what you're looking for in the end.
Can you give a short example?
> That's definitely an interesting approach, but testing doesn't show it
> to be appreciably faster.
>
> If I do a DISTINCT *, postgres will attempt to guarantee that there are
> no duplicate values across all columns rather than a subset of columns?
> Is that right?
It guarantees one output row for each distinct set of column values across
all columns.
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To: pgsql-sql@postgresql.org
Cc: sszabo@megazone.bigpanda.com, tfo@sitening.com
Subject: Re: Counting Distinct Records
In-Reply-To: <20041117064813.V17486@megazone.bigpanda.com>
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