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From: Ranier Vilela <ranier.vf@gmail.com>
Date: Thu, 18 Sep 2025 13:48:08 -0300
Message-ID: 
 <CAEudQApK3JRz75X8_8zSiC3oAMgnZRcLsjYTqtwQWH=Ytdh21Q@mail.gmail.com>
Subject: Re: Indexes on expressions with multiple columns and operators
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: =?UTF-8?B?RnLDqWTDqXJpYyBZaHVlbA==?= <frederic.yhuel@dalibo.com>,
	"pgsql-performance@lists.postgresql.org"
 <pgsql-performance@lists.postgresql.org>,
	Jehan-Guillaume de Rorthais <jgdr@dalibo.com>,
 Christophe Courtois <christophe.courtois@dalibo.com>,
	Laurenz Albe <laurenz.albe@cybertec.at>
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Em qui., 18 de set. de 2025 =C3=A0s 13:40, Tom Lane <tgl@sss.pgh.pa.us> esc=
reveu:

> 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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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote g=
mail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">Em qui., 18 de =
set. de 2025 =C3=A0s 13:40, Tom Lane &lt;<a href=3D"mailto:tgl@sss.pgh.pa.u=
s">tgl@sss.pgh.pa.us</a>&gt; escreveu:<br></div><blockquote class=3D"gmail_=
quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,=
204);padding-left:1ex">I wrote:<br>
&gt; Sigh ... so the answer is this used to work (since commit 39df0f150)<b=
r>
&gt; and then I carelessly broke it in commit a391ff3c3.=C2=A0 If you try t=
his<br>
&gt; test case in versions 9.5..11 you get a spot-on rowcount estimate.<br>
&gt; Serves me right for not having a test case I guess, but I&#39;m astoni=
shed<br>
&gt; that nobody complained sooner.<br>
<br>
The attached fixes things so it works like it did pre-a391ff3c3.<br>
<br>
I spent some time trying to devise a test case, and was reminded<br>
of why I didn&#39;t have one before: it&#39;s hard to make a case that<br>
will be robust enough to not show diffs in the buildfarm.<br>
I&#39;ll keep thinking about that though.<br></blockquote><div>One question=
, make difference return -1.0 (float point notation)?</div><div>If not, sta=
tic analyzers=C2=A0will have less work.</div><div><br></div><div>best regar=
ds,</div><div>Ranier Vilela</div></div></div>

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