Re: Optimize expresiions.

han(dot)holl(at)informationslogik(dot)nl wrote:
> On Thursday 11 January 2007 12:34, Richard Huxton wrote:
>
>>> The query would run much faster with the filter reordered.
>>> Is there a way to tell the planner/optimizer that certain functions are
>>> more expensive than others, and should be postponed in lazy evaluation ?
>>> Or is there a hook in the system that would allow me too look at and
>>> maybe reorder expressions before they are executed ?
>> Not really. Perhaps look into using a functional/expressional index and
>> see if that does the job for you.
>>
> Oh well, pity. Thanks anyway.
> In my case, indexes don't help.

Maybe your functions can be marked STABLE or even IMMUTABLE? That should
help the planner evaluate them less often.

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Alban Hertroys
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