Re: parameter hints to the optimizer - Mailing list pgsql-hackers

From Hans-Jürgen Schönig
Subject Re: parameter hints to the optimizer
Date
Msg-id 40FEC44E.6030504@cybertec.at
Whole thread Raw
In response to parameter hints to the optimizer  ("Merlin Moncure" <merlin.moncure@rcsonline.com>)
List pgsql-hackers
Merlin Moncure wrote:
>>Merlin,
>>
>>This will most likely never be accepted by the core team because it is
>>better to spend more time on fixing the planner than to invent some
>>non-standard.
>>As far as I know some databases support a syntax where hints can be
>>hidden in comments or something like that.
>>Meanwhile I think that hints are more of a burdon than a help.
>>
>>    Regards,
>>
>>        Hans
> 
> 
> I thought as much.  Still, the parameter problem is a huge headache.  Maybe if it was possible to use the statistics
togather a 'pseudovariable' to feed to the parameter based on some algorithm, the planner could give better results
withoutexposing the planner inner workings to the user.
 
> 
> Thanks for the feedback.
> Merlin



Using statistics is exactly what the planner does ...
So why should data coming from the planner being given back to the 
planner? Doesn't make sense.

For more information I highly recommend Tom's talk at Oreilly's some 
time ago. I think it is called "recent improvements in 7.4" ...
regards,
    Hans



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