Horton

Re: should check interrupts in BuildRelationExtStatistics ?

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Tomas Vondra <tomas.vondra@enterprisedb.com>, pgsql-hackers@postgresql.org
Date: 2022-06-17T22:25:49Z
Lists: pgsql-hackers

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On Mon, Jun 06, 2022 at 04:23:34PM +0900, Michael Paquier wrote:
> On Sat, Jun 04, 2022 at 08:42:33PM -0500, Justin Pryzby wrote:
> > The fix seems to be to CHECK_FOR_INTERRUPTS() within multi_sort_compare().
> > That would supercede the other two CHECK_FOR_INTERRUPTS I'd proposed, and
> > handle mcv, depends, and ndistinct all at once.
> 
> Hmm.  I have to admit that adding a CFI() in multi_sort_compare()
> stresses me a bit as it is dependent on the number of rows involved,
> and it can be used as a qsort routine.

That's exactly the problem for which I showed a backtrace - it took 10s of
seconds to do qsort, which is (uh) a human timescale and too long to be
unresponsive, even if I create on a table with many rows a stats object with a
lot of columns and a high stats target.

Commits

  1. Invent qsort_interruptible().