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Re: Need advice to avoid ORDER BY - Mailing list pgsql-general

From Scott Marlowe
Subject Re: Need advice to avoid ORDER BY
Date
Msg-id CAOR=d=1FwYehYpoZJ4ER82PqVYKh9N9rOCHkmWno1iO+Y5RjuQ@mail.gmail.com
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In response to Need advice to avoid ORDER BY  (Condor <condor@stz-bg.com>)
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Try an index like:

create index yada on mytable (id) where valids=0;

then

select max(jobid) from mytable where valids=0;


On Thu, Apr 4, 2013 at 3:32 PM, Condor <condor@stz-bg.com> wrote:
Hello,

I have one query in my postgresql 9.2.3 that took 137 ms to me executed and looking a way
what I can do to optimize it. I have one table generated numbers from 1 to 1 000 000 and
I need to get first free id, meanwhile id's when is taken can be free (deleted data and id
is free for next job). Table is simple:


id serial,
jobid text,
valids int default 0

(Yes, I have index).


my query is: SELECT jobid FROM mytable WHERE valids = 0 ORDER BY id ASC LIMIT 1

I need the first id only.

My question is: Is there a way how I can avoid using ORDER BY to receive the first
free id from mytable ?



Cheers,
Condor



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