Re: Rework manipulation and structure of attribute mappings

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: Amit Langote <amitlangote09(at)gmail(dot)com>
Cc: Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Rework manipulation and structure of attribute mappings
Date: 2019-12-18 07:26:44
Message-ID: 20191218072644.GB197628@paquier.xyz
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On Tue, Dec 17, 2019 at 01:54:27PM +0900, Amit Langote wrote:
> Thanks for the updated patch. I don't have any comments, except that
> the text I suggested couple of weeks ago no longer reads clear:

I have spent a couple of extra hours on the patch, and committed it.
There was one issue in logicalrelation.h which failed to compile
standalone.

> + * by DDL operating on inheritance and partition trees to convert fully
> + * transformed expression trees from parent rowtype to child rowtype or
> + * vice-versa.
>
> Maybe:
>
> ...to adjust the Vars in fully transformed expression trees to bear
> output relation's attribute numbers.

I have used something more generic at the end:
+ * mappings by comparing input and output TupleDescs. Such mappings
+ * are typically used by DDL operating on inheritance and partition trees
+ * to do a conversion between rowtypes logically equivalent but with
+ * columns in a different order, taking into account dropped columns.
--
Michael

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