Re: unneeded joins on view

On 16/04/14 17:57, Heikki Linnakangas wrote:
> On 04/16/2014 06:13 PM, Linos wrote:
>> I thought that Postgresql would optimize out joins on columns I
>> don't ask for when I use the view but it doesn't, this query:
>
> It doesn't, because it would be wrong. It still has to check that the tables have a matching row (or multiple
matchingrows). 
>
> If you use LEFT JOINs instead, and have a unique index on all the ID columns, then the planner can do what you
expectedand leave out the joins. 
>
> - Heikki
>
>

You are right, I knew I was forgetting something important but I didn't know what was, thank you Heikki.

Regards,
Miguel Angel.