Re: [HACKERS] Partition-wise join for join between (declaratively) partitioned tables

From: Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>
To: Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Rafia Sabih <rafia(dot)sabih(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] Partition-wise join for join between (declaratively) partitioned tables
Date: 2017-12-05 07:54:31
Message-ID: CAKcux6=h6PJMgeNwPScJ5Zz4P4AZWf+nxgn46eTeOb-prQP14w@mail.gmail.com
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On Tue, Dec 5, 2017 at 11:04 AM, Rajkumar Raghuwanshi
<rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com> wrote:
> On Mon, Dec 4, 2017 at 7:34 AM, Ashutosh Bapat
> <ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:
>> I agree, the patch looks longer than expected. I think, it's important
>> to have some testcases to test partition-wise join with default
>> partitions. I think we need at least one test for range default
>> partitions, one test for list partitioning, one for multi-level
>> partitioning and one negative testcase with default partition missing
>> from one side of join.
>>
>> May be we could reduce the number of SQL commands and queries in the
>> patch by adding default partition to every table that participates in
>> partition-wise join (leave the tables participating in negative tests
>> aside.). But that's going to increase the size of EXPLAIN outputs and
>> query results. The negative test may simply drop the default partition
>> from one of the tables.
>>
>> For every table being tested, the patch adds two ALTER TABLE commands,
>> one for detaching an existing partition and then attach the same as
>> default partition. Alternative to that is just add a new default
>> partition without detaching and existing partition. But then the
>> default partition needs to populated with some data, which requires 1
>> INSERT statement at least. That doesn't reduce the size of patch, but
>> increases the output of query and EXPLAIN plan.
>>
>> May be in case of multi-level partitioning test, we don't need to add
>> DEFAULT in every partitioned relation; adding to one of them would be
>> enough. May be add it to the parent, but that too can be avoided. That
>> would reduce the size of patch a bit.
>
> Thanks Ashutosh for suggestions.
>
> I have reduced test cases as suggested. Attaching updated patch.
>
Sorry Attached wrong patch.

attaching correct patch now.

Attachment Content-Type Size
partition_wise_join_with_default_partitions_v2.patch text/x-patch 11.0 KB

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