Re: enable_seqscan to off -> initial cost 10000000000

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От David Rowley
Тема Re: enable_seqscan to off -> initial cost 10000000000
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Msg-id CAApHDvoJqBcqBnRMB-09vy8r2sh0HRt4SsuXiKV3Mbzq1uxi7Q@mail.gmail.com
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Ответ на Re: enable_seqscan to off -> initial cost 10000000000  (Ron <ronljohnsonjr@gmail.com>)
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On Sat, 24 Apr 2021 at 03:44, Ron <ronljohnsonjr@gmail.com> wrote:
>
> On 4/23/21 10:39 AM, Luca Ferrari wrote:
> > Hi all,
> > this could be trivial, but I would like an explaination: if I turn off
> > sequential scans on a table without indexes, the same access plan is
> > increased by a 10000000000 factor. I suspect this is a warning for me
> > to remind that something is misconfigured, or is there anothe reason?
>
> Maybe I'm missing something, but in "a table without indexes", what else is
> there besides sequential scan?

You're not really missing anything.

However, technically, in the yet-to-be-released PG14, if the query had
a TID qual then you could disable seqscan to encourage a TID Range
scan. That's a bit of a stretch of the imagination though.

David



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