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Re: tricky query

From: John A Meinel <john(at)arbash-meinel(dot)com>
To: Merlin Moncure <merlin(dot)moncure(at)rcsonline(dot)com>
Cc: Postgresql Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: tricky query
Date: 2005-06-28 15:43:25
Message-ID: 42C1701D.5040102@arbash-meinel.com (view raw or flat)
Thread:
Lists: pgsql-performance
Merlin Moncure wrote:

>>Not so bad. Try something like this:
>>
>>SELECT min(id+1) as id_new FROM table
>>    WHERE (id+1) NOT IN (SELECT id FROM table);
>>
>>Now, this requires probably a sequential scan, but I'm not sure how
>>
>>
>you
>
>
>>can get around that.
>>Maybe if you got trickier and did some ordering and limits. The above
>>seems to give the right answer, though.
>>
>>
>
>it does, but it is still faster than generate_series(), which requires
>both a seqscan and a materialization of the function.
>
>
>
>>I don't know how big you want to scale to.
>>
>>
>
>big. :)
>
>merlin
>
>

See my follow up post, which enables an index scan. On my system with
90k rows, it takes no apparent time.
(0.000ms)
John
=:->

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