Re: [HACKERS] path toward faster partition pruning

From: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Beena Emerson <memissemerson(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] path toward faster partition pruning
Date: 2018-02-28 01:12:07
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On 2018/02/28 1:05, Robert Haas wrote:
> On Mon, Feb 26, 2018 at 10:59 PM, Amit Langote
> <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>> You may say that partition bounds might have to be different too in this
>> case and hence partition-wise join won't occur anyway, but I'm wondering
>> if the mismatch of partcollation itself isn't enough to conclude that?
> Yeah, you're right. I think that this is just a bug in partition-wise
> join, and that the partition scheme should just be using partcollation
> instead of parttypcoll, as in the attached.

Ah, OK. I was missing that there is no need to have both parttypcoll and
partcollation in PartitionSchemeData, as the Vars in rel->partexprs are
built from a bare PartitionKey (not PartitionSchemeData), and after that
point, parttypcoll no longer needs to kept around.

I noticed that there is a typo in the patch.

+ memcpy(part_scheme->partcollation, partkey->parttypcoll,


BTW, should there be a relevant test in partition_join.sql? If yes,
attached a patch (partitionwise-join-collation-test-1.patch) to add one.

Also attached updated version of your patch (fixed the typo).


Attachment Content-Type Size
partition-scheme-collation-2.patch text/plain 1.8 KB
partitionwise-join-collation-test-1.patch text/plain 2.5 KB

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