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

From: Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Partition-wise join for join between (declaratively) partitioned tables
Date: 2017-03-17 13:15:45
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> Here's the set of patches with all the memory saving stuff removed.
> It's now bare partition-wise joins. I have tried to eliminate all
> memory saving stuff carefully, except few bms_free() and list_free()
> which fit the functions they were part of and mostly were present in
> my earlier versions of patches. But I might have missed some. Also, I
> have corrected any indentation/white space mistakes introduced by
> editing patches with +/-, but I might have missed some. Please let me
> know.

Rajkumar offlist reported two issues with earlier set of patches.
1. 0008 conflicted with latest changes in postgres_fdw/deparse.c.

2. In the earlier set of patches part_scheme of a join relation was
being set when joining relations had same part_scheme even if there
was no equi-join between partition keys. The idea being that
rel->part_scheme and rel->part_rels together tell whether a relation
is partitioned or not. At a later stage if none of the joining pairs
resulted in partitioned join, part_rels would be NULL and then we
would reset part_scheme as well. But this logic not required. For the
exact partition scheme matching, that we are using, if one pair of
joining relation has an equi-join on partition keys, and both of those
have exactly same partitioning scheme, all other pairs of joining
relations would have an equi-join on partition keys and also exactly
same partitioning scheme. So, we can set part_scheme only by looking
at the first pair of joining relation while building the child-join.

This set of patches fixes both of those things.

Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

Attachment Content-Type Size application/zip 65.7 KB

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