| From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
|---|---|
| To: | Ivan Sergio Borgonovo <mail(at)webthatworks(dot)it> |
| Cc: | PGSQL <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: functional index not used, looping simpler query just faster |
| Date: | 2008-07-10 09:50:01 |
| Message-ID: | 20080710095001.GA18528@svana.org |
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| Lists: | pgsql-general |
On Thu, Jul 10, 2008 at 11:40:40AM +0200, Ivan Sergio Borgonovo wrote:
> I've this:
What's basically killing you is this condition:
> select i2.ItemID from catalog_items i2
> inner join catalog_brands b2 on upper(i2.brands)=upper(b2.name)
> where i1.brands=i2.brands <*********
> and i2.dataPub>(now() - interval '8 month') and
Is not indexable. Hence the seqscan, which makes everything slow.
In your "faster" version you test against a condition which *is*
indexable, hence it's faster.
Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Please line up in a tree and maintain the heap invariant while
> boarding. Thank you for flying nlogn airlines.
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