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From: Tender Wang <tndrwang@gmail.com>
Date: Thu, 29 Aug 2024 11:22:24 +0800
Message-ID: <CAHewXNn8zB5vH7r6bASznviYY-oJL_pxJyo=s6fPA+NV1_hv2g@mail.gmail.com>
Subject: Re: Eager aggregation, take 3
To: Richard Guo <guofenglinux@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Paul George <p.a.george19@gmail.com>, 
	Andy Fan <zhihuifan1213@163.com>, 
	PostgreSQL-development <pgsql-hackers@postgresql.org>, pgsql-hackers@lists.postgresql.org
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Richard Guo <guofenglinux@gmail.com> =E4=BA=8E2024=E5=B9=B48=E6=9C=8829=E6=
=97=A5=E5=91=A8=E5=9B=9B 10:46=E5=86=99=E9=81=93=EF=BC=9A

> On Wed, Aug 28, 2024 at 9:01=E2=80=AFPM Robert Haas <robertmhaas@gmail.co=
m> wrote:
> > On Tue, Aug 27, 2024 at 11:57=E2=80=AFPM Tender Wang <tndrwang@gmail.co=
m> wrote:
> > > I haven't look all of them. I just pick few simple plan test(e.g.
> 19.sql, 45.sql).
> > > For example, 19.sql, eager agg pushdown doesn't get large gain, but a
> little
> > > performance regress.
> >
> > Yeah, this is one of the things I was worried about in my previous
> > reply to Richard. It would be worth Richard, or someone, probing into
> > exactly why that's happening. My fear is that we just don't have good
> > enough estimates to make good decisions, but there might well be
> > another explanation.
>
> It's great that we have a query to probe into.  Your guess is likely
> correct: it may be caused by poor estimates.
>
> Tender, would you please help provide the outputs of
>
> EXPLAIN (COSTS ON, ANALYZE)
>
> on 19.sql with and without eager aggregation?
>

Yeah, in [1], 19_off.out and 19_on.out are the output of explain(costs off,
analyze).
I will do EXPLAIN(COSTS ON, ANALYZE) tests and upload them later today.


[1] https://github.com/tenderwg/eager_agg


--=20
Tender Wang

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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote">=
<div dir=3D"ltr" class=3D"gmail_attr">Richard Guo &lt;<a href=3D"mailto:guo=
fenglinux@gmail.com">guofenglinux@gmail.com</a>&gt; =E4=BA=8E2024=E5=B9=B48=
=E6=9C=8829=E6=97=A5=E5=91=A8=E5=9B=9B 10:46=E5=86=99=E9=81=93=EF=BC=9A<br>=
</div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;b=
order-left:1px solid rgb(204,204,204);padding-left:1ex">On Wed, Aug 28, 202=
4 at 9:01=E2=80=AFPM Robert Haas &lt;<a href=3D"mailto:robertmhaas@gmail.co=
m" target=3D"_blank">robertmhaas@gmail.com</a>&gt; wrote:<br>
&gt; On Tue, Aug 27, 2024 at 11:57=E2=80=AFPM Tender Wang &lt;<a href=3D"ma=
ilto:tndrwang@gmail.com" target=3D"_blank">tndrwang@gmail.com</a>&gt; wrote=
:<br>
&gt; &gt; I haven&#39;t look all of them. I just pick few simple plan test(=
e.g. 19.sql, 45.sql).<br>
&gt; &gt; For example, 19.sql, eager agg pushdown doesn&#39;t get large gai=
n, but a little<br>
&gt; &gt; performance regress.<br>
&gt;<br>
&gt; Yeah, this is one of the things I was worried about in my previous<br>
&gt; reply to Richard. It would be worth Richard, or someone, probing into<=
br>
&gt; exactly why that&#39;s happening. My fear is that we just don&#39;t ha=
ve good<br>
&gt; enough estimates to make good decisions, but there might well be<br>
&gt; another explanation.<br>
<br>
It&#39;s great that we have a query to probe into.=C2=A0 Your guess is like=
ly<br>
correct: it may be caused by poor estimates.<br>
<br>
Tender, would you please help provide the outputs of<br>
<br>
EXPLAIN (COSTS ON, ANALYZE)<br>
<br>
on 19.sql with and without eager aggregation?<br></blockquote><div><br></di=
v><div>Yeah, in [1], 19_off.out and 19_on.out are the output of explain(cos=
ts off, analyze).</div><div>I will do EXPLAIN(COSTS ON, ANALYZE) tests and =
upload them later today.</div><div><br></div><div><br></div><div>[1]=C2=A0<=
a href=3D"https://github.com/tenderwg/eager_agg">https://github.com/tenderw=
g/eager_agg</a>=C2=A0</div></div><br clear=3D"all"><div><br></div><span cla=
ss=3D"gmail_signature_prefix">-- </span><br><div dir=3D"ltr" class=3D"gmail=
_signature"><div dir=3D"ltr"><div>Tender Wang</div></div></div></div>

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