Re: Need to increase performance of a query

From: Anne Rosset <arosset(at)collab(dot)net>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Craig James <craig_james(at)emolecules(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Need to increase performance of a query
Date: 2010-06-10 20:08:27
Message-ID: 4C11463B.7080608@collab.net
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Heikki Linnakangas wrote:
> On 10/06/10 22:47, Craig James wrote:
>> Postgres normally doesn't index NULL values even if the column is
>> indexed, so it has to do a table scan when your query includes an IS
>> NULL condition.
>
> That was addressed in version 8.3. 8.3 and upwards can use an index
> for IS NULL.
>
> I believe the NULLs were stored in the index in earlier releases too,
> they just couldn't be searched for.
>
I am using postgres 8.3.6. So why doesn't it use my index?
Thanks,
Anne

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