Re: Getting query plan alternatives from query planner?

On Fri, Mar 21, 2014 at 1:07 PM, Stefan Keller <sfkeller@gmail.com> wrote:

Hi Tom

You wrote:
> Path alternatives are rejected
> whenever possible before moving up to the next join level, so that what
> we have rejected is actually just a plan fragment in most cases.

Thanks for the quick answer. This sounds like a fair implementation decision.

Background for asking this is of course, that one want's 1. to
understand and 2. influence the optimizer in cases where one thinks
that the planner is wrong :-).

So, the bottom line is
1. that PostgreSQL doesn't offer no means to understand the planner
except EXPLAIN-ing the chosen plan?
2. and there's no road map to introduce planner hinting (like in
EnterpriseDB or Ora)?

We recently had some discussion for planner hints. There is no plan for having planner hints ATM. However, we are looking at ways at which we can improve the query planner for some cases where it makes statistical bad estimations and gives bad plans.

Regards,

Atri

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Regards,

 

Atri

l'apprenant