Re: ExplainModifyTarget doesn't work as expected

From: Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: ExplainModifyTarget doesn't work as expected
Date: 2015-02-12 05:05:31
Message-ID: 54DC349B.9030404@lab.ntt.co.jp
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On 2015/02/10 14:49, Etsuro Fujita wrote:
> On 2015/02/07 1:09, Tom Lane wrote:
>> IIRC, this code was written at a time when we didn't have NO INHERIT check
>> constraints and so it was impossible for the parent table to get optimized
>> away while leaving children. So the comment in ExplainModifyTarget was
>> good at the time. But it no longer is.
>>
>> I think your basic idea of preserving the original parent table's relid
>> is correct; but instead of doing it like this patch does, I'd be inclined
>> to make ModifyTable inherit from Scan not Plan, and use the scan.scanrelid
>> field to carry the parent RTI. Then you would probably end up with a net
>> savings of code rather than net addition; certainly ExplainModifyTarget
>> would go away entirely since you'd just treat ModifyTable like any other
>> Scan in this part of EXPLAIN.
>
> Will follow your revision.

Done. Attached is an updated version of the patch.

Best regards,
Etsuro Fujita

Attachment Content-Type Size
explain-inherited-updates-v2.patch text/x-patch 10.8 KB

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