| From: | Ranier Vilela <ranier(dot)vf(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Frédéric Yhuel <frederic(dot)yhuel(at)dalibo(dot)com>, "pgsql-performance(at)lists(dot)postgresql(dot)org" <pgsql-performance(at)lists(dot)postgresql(dot)org>, Jehan-Guillaume de Rorthais <jgdr(at)dalibo(dot)com>, Christophe Courtois <christophe(dot)courtois(at)dalibo(dot)com>, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
| Subject: | Re: Indexes on expressions with multiple columns and operators |
| Date: | 2025-09-18 16:48:08 |
| Message-ID: | CAEudQApK3JRz75X8_8zSiC3oAMgnZRcLsjYTqtwQWH=Ytdh21Q@mail.gmail.com |
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| Lists: | pgsql-performance |
Em qui., 18 de set. de 2025 às 13:40, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> escreveu:
> I wrote:
> > Sigh ... so the answer is this used to work (since commit 39df0f150)
> > and then I carelessly broke it in commit a391ff3c3. If you try this
> > test case in versions 9.5..11 you get a spot-on rowcount estimate.
> > Serves me right for not having a test case I guess, but I'm astonished
> > that nobody complained sooner.
>
> The attached fixes things so it works like it did pre-a391ff3c3.
>
> I spent some time trying to devise a test case, and was reminded
> of why I didn't have one before: it's hard to make a case that
> will be robust enough to not show diffs in the buildfarm.
> I'll keep thinking about that though.
>
One question, make difference return -1.0 (float point notation)?
If not, static analyzers will have less work.
best regards,
Ranier Vilela
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