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Re: How to construct an exact plan

From: PostgreSQL - Hans-Jürgen Schönig <postgres(at)cybertec(dot)at>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: Pei He <hepeimail(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: How to construct an exact plan
Date: 2010-08-31 07:10:25
Message-ID: D5D77B72-D369-496B-B8BE-1508088C4A07@cybertec.at (view raw or flat)
Thread:
Lists: pgsql-hackers
hello ...

here is the ultimate revelation of planner hints in postgres ...
let us praise oleg and teodor for solving a practical problem for practical people ...

http://www.sai.msu.su/~megera/wiki/plantuner

try this one ...
it is excellent and definitely helpful for many many people out there.
unfortunately this code is not too well known.

	many thanks,

		hans



On Aug 30, 2010, at 9:41 PM, Pavel Stehule wrote:

> 2010/8/30 Pei He <hepeimail(at)gmail(dot)com>:
>> Hi,
>> 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.
>> 
> 
> yes, it is possible - but it isn't simple. I thing, so better is
> simple implementation of all parts and then runtime blocking some (for
> you not interesting) buildin methods via SET enable_.... to off.
> 
> Regards
> 
> Pavel Stehule
> 
>> 
>> Thanks
>> --
>> Pei
>> 
>> 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.
>>>                                     http://www.pgexperts.com
>>> 
>> 
>> --
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> 
> -- 
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