Re: SELECT DISTINCT too slow

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Miroslav ?ulc <miroslav(dot)sulc(at)startnet(dot)cz>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: SELECT DISTINCT too slow
Date: 2006-06-01 14:53:28
Message-ID: 20060601145327.GA19388@surnet.cl
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Miroslav ?ulc wrote:
> Well, "key" is not primary key from another table. It is just a column
> in pair "key" => "value".
> The structure of the table is this:
>
> Id (primary key)
> MRTPContactId (id of contact from table MRTPContact)
> Key (key from pair key => value)
> Value (value from pair key => value)
>
> So I want the get the list of keys used in the table.

The plan you get is the most efficient possible for that query. If you
had a table of possible keys (which should of course be FK of "Key"),
you could get a much faster version :-)

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

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