Re: index vs. seq scan choice?

George Pavlov wrote:
>> From: Tom Lane
>> "George Pavlov" <gpavlov@mynewplace.com> writes:
>>>> From: Joshua D. Drake [mailto:jd@commandprompt.com]
>>>> In those rare cases wouldn't it make more sense to just set
>>>> enable_seqscan to off; run query; set enable_seqscan to on;
>>> 1. these cases are not that rare (to me);
>> It strikes me that you probably need to adjust the planner cost
>> parameters to reflect reality on your system.  Usually dropping
>> random_page_cost is the way to bias the thing more in favor of
>> index scans.
>
> Thanks, Tom, I will try that. Seems better than fiddling with
> enable_seqscan around every query/transaction.
>
> Joshua, I fail to understand why setting and unsetting enable_seqscan on
> a per query/transaction basis is in any way preferable to query hints?
> Don't get me wrong, I don't like the idea of hints, and I have read the
> archives on the subject and I agree with the philosophy, but if the
> optimization toolkit for routine application queries is going to include
> setting config parameters that just smacks of hints by another name...

I actually have zero opinion on hints, my comment was more about opening
the wasps nest of the hints discussion more than anything :)

Joshua D. Drake


>
> George
>


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