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Re: How to construct an exact plan

From: Pei He <hepeimail(at)gmail(dot)com>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: How to construct an exact plan
Date: 2010-08-30 19:22:31
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
I am hacking postgresql 8.2.5. a) and b) do not work for me.

The situation is that I made a join operator, and a scan operator.
And, The join operator requires the scan operator as the inner. So, I
need to have the full control of the join plan.

I am not ready to provide the optimization support for the two new
operators. And, I want to run some performance tests before working on
the optimization part.

So, I want to know if it is possible to directly create a path or a
plan, and do a unit test for the operators.


On Mon, Aug 30, 2010 at 1:59 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>> I have developed a new operators, and I want to do some tests on it.
>> I do not want the optimizer to choose the plan for me, and I need to
>> construct a plan as exact as I want.
>> Can anyone provide me a way to achieve that?
> a) easy: choose a simple enough query that its plan is always predictable.
> b) moderate: choose a query whose plan is predictable if you manipulate
> the enable_* configuration settings
> c) hard: hack the PostgreSQL planner to choose a specific execution
> plan, and recompile Postgres.
> --
>                                  -- Josh Berkus
>                                     PostgreSQL Experts Inc.

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