Re: PostgreSQL OR performance

As far as i know if you created the indexes properly and postgres sees that
it will give some improvement he will use those.
- Look at the page of index creation that we may be forgeting some thing.

http://www.postgresql.org/docs/8.3/static/indexes.html

I have to go to the hospital know. Tomorrow i will take a look at the manual
and try to understand all the necessary for the postgresql use an index.

Regards

On Thu, Nov 6, 2008 at 2:33 PM, Віталій Тимчишин <tivv00(at)gmail(dot)com> wrote:

>
>
> 2008/11/6 Helio Campos Mello de Andrade <helio(dot)campos(at)gmail(dot)com>
>
>> For what i see in four OR-plan.txt tou are doing too much "sequencial
>> scan" . Create some indexes for those tables using the fields that you use
>> an it may help you.
>>
>> OBS: If you already have lots of indexes in your tables it may be a good
>> time for you re-think your strategy because it´s ot working.
>> Tips:
>> 1 - create indexes for the tables with the fields that you will use in
>> the query if it is your most important query. If you have others querys that
>> are used please post those here and we can help you to desing a better plan.
>
>
> As you can see from other plans, it do have all the indexes to perform it's
> work fast (when given part by part). It simply do not wish to use them. My
> question: Is this a configuration problem or postgresql optimizer simply
> can't do such a query rewrite?
>
> Actually I did rewrite the query to work properly as you can see from
> union-plan.txt. My question is if postgresql can do this automatically
> because such a rewrite is not always easy/possible (esp. for generated
> queries)?
>
>

--
Helio Campos Mello de Andrade