Re: Asymmetric partition-wise JOIN

From: Andrey Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>
To: Zhihong Yu <zyu(at)yugabyte(dot)com>
Cc: Alexander Pyhalov <a(dot)pyhalov(at)postgrespro(dot)ru>, Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru>, Daniel Gustafsson <daniel(at)yesql(dot)se>, Kohei KaiGai <kaigai(at)heterodb(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Asymmetric partition-wise JOIN
Date: 2021-07-15 06:32:34
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On 5/7/21 23:15, Zhihong Yu wrote:
> On Mon, Jul 5, 2021 at 2:57 AM Andrey Lepikhov
> <a(dot)lepikhov(at)postgrespro(dot)ru <mailto:a(dot)lepikhov(at)postgrespro(dot)ru>> wrote:
> +            * Can't imagine situation when join relation already
> exists. But in
> +            * the 'partition_join' regression test it happens.
> +            * It may be an indicator of possible problems.
> Should a log be added in the above case ?
I worked more on this case and found more serious mistake. During
population of additional paths on the existed RelOptInfo we can remove
some previously generated paths that pointed from a higher-level list of
subplans and it could cause to lost of subplan links. I prohibit such
situation (you can read comments in the new version of the patch).
Also, choosing of a cheapest path after appendrel creation was added.
Unstable tests were fixed.

Andrey Lepikhov
Postgres Professional

Attachment Content-Type Size
v17-0001-Asymmetric-partitionwise-join.patch text/plain 35.0 KB

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