Date: Tue, 24 Mar 2026 14:44:38 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Greg Burd <greg@burd.me>
Cc: Jeff Davis <pgsql@j-davis.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Expanding HOT updates for expression and partial indexes
Message-ID: <acLppkl4hutHhiuH@nathan>
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On Tue, Mar 24, 2026 at 02:02:07PM -0400, Greg Burd wrote:
> On Mon, Mar 23, 2026, at 2:39 PM, Nathan Bossart wrote:
>> On Tue, Mar 17, 2026 at 02:04:11PM -0400, Greg Burd wrote:
>>> - *	INDEX_ATTR_BITMAP_SUMMARIZED	Columns included in summarizing indexes
>>> + *	INDEX_ATTR_BITMAP_INDEXED		Columns referenced by indexes
>>> + *	INDEX_ATTR_BITMAP_SUMMARIZED	Columns only included in summarizing indexes
>>
>>> -	Bitmapset  *summarizedattrs;	/* columns with summarizing indexes */
>>> +	Bitmapset  *indexedattrs;	/* columns referenced by indexes */
>>> +	Bitmapset  *summarizedattrs;	/* columns only in summarizing indexes */
>>
>> As before, the comment changes for the summarized-attr-related stuff seem
>> unnecessary.
> 
> I disagree, the "only" is required to highlight the logic change here.
> Before this patch summarized attrs could overlap with indexed attrs, now
> it should not.  This makes the logic a bit easier later in
> HeapUpdateHotAllowable().

My bad, you are right.

> So, we go from 3 calls to RelationGetIndexAttrBitmap() to 1, or at most 2
> when there's a summarizing index (which is frequently the case).
> 
> This feels more logical, cleaner, and has less overhead but supports the
> same HOT logic.

Nice.

-- 
nathan