RE: speeding up planning with partitions

From: "Imai, Yoshikazu" <imai(dot)yoshikazu(at)jp(dot)fujitsu(dot)com>
To: 'Tom Lane' <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
Cc: Imai Yoshikazu <yoshikazu_i443(at)live(dot)jp>, "jesper(dot)pedersen(at)redhat(dot)com" <jesper(dot)pedersen(at)redhat(dot)com>, 'Amit Langote' <amitlangote09(at)gmail(dot)com>, "David Rowley" <david(dot)rowley(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, "Justin Pryzby" <pryzby(at)telsasoft(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: RE: speeding up planning with partitions
Date: 2019-03-25 01:47:23
Message-ID: 0F97FA9ABBDBE54F91744A9B37151A512B83AE@g01jpexmbkw24
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On Fri, Mar 22, 2019 at 9:07 PM, Tom Lane wrote:
> BTW, it strikes me that we could take advantage of the fact that baserels
> must all appear before otherrels in the rel array, by having loops over
> that array stop early if they're only interested in baserels. We could
> either save the index of the last baserel, or just extend the loop logic
> to fall out upon hitting an otherrel.
> Seems like this'd save some cycles when there are lots of partitions,
> although perhaps loops like that would be fast enough to not matter.

Actually, this speeds up planning time little when scanning a lot of otherrels like selecting thousands of partitions. I tested below.

* rt with 8192 partitions
* execute "select * from rt;" for 60 seconds.

[results]
HEAD: 4.19 TPS (4.06, 4.34, 4.17)
(v34 patches) + (looping over only baserels): 4.26 TPS (4.31, 4.28, 4.19)

Attached is the diff I used for this test.

--
Yoshikazu Imai

Attachment Content-Type Size
looping-over-last-baserel-idx.diff application/octet-stream 5.6 KB

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