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From: Nathan Bossart <nathandbossart@gmail.com>
To: Greg Burd <greg@burd.me>
Cc: Jeff Davis <pgsql@j-davis.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Expanding HOT updates for expression and partial indexes
Date: Tue, 24 Mar 2026 14:44:38 -0500
Message-ID: <acLppkl4hutHhiuH@nathan> (raw)
In-Reply-To: <db765e0d-4674-4547-9a9d-6d4d9a0a123c@app.fastmail.com>
References: <811d6f42e5481935943556b692859aae9146d4c9.camel@j-davis.com>
	<b0404aab-65a1-4922-9cff-986163ad70bb@app.fastmail.com>
	<7b8681a578b5fe77103948eeb7b5cdd80fabad5d.camel@j-davis.com>
	<4f48f75d-4f2a-4240-b66d-597517796e02@app.fastmail.com>
	<3fba3f5671eddb221ba38f5a12acbe7cad27edf3.camel@j-davis.com>
	<427bfbda-c901-49e4-b725-8ddc41bec23d@app.fastmail.com>
	<887b1ee62794553a95c3578fcdc0cc1831e68b27.camel@j-davis.com>
	<d7489d3e-2cbd-4b0f-b662-b5c4386a3f1e@app.fastmail.com>
	<acGI-wnW4NxS87e0@nathan>
	<db765e0d-4674-4547-9a9d-6d4d9a0a123c@app.fastmail.com>

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





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  To: pgsql-hackers@postgresql.org
  Cc: nathandbossart@gmail.com, greg@burd.me, pgsql@j-davis.com
  Subject: Re: Expanding HOT updates for expression and partial indexes
  In-Reply-To: <acLppkl4hutHhiuH@nathan>

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