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From: Tomas Vondra <[email protected]>
To: Melanie Plageman <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Pg Hackers <[email protected]>
Cc: Thomas Munro <[email protected]>
Cc: Heikki Linnakangas <[email protected]>
Cc: Nazir Bilal Yavuz <[email protected]>
Subject: Re: BitmapHeapScan streaming read user and prelim refactoring
Date: Wed, 28 Feb 2024 20:23:28 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <CAAKRu_ZwCwWFeL_H3ia26bP2e7HiKLWt0ZmGXPVwPO6uXq0vaA@mail.gmail.com>
	<[email protected]>
	<CAAKRu_bQ9a2dB42Tz-mrsR+2MuG-ojRmqbX-x-TC08Uo_RunNw@mail.gmail.com>
	<20240216173559.xiy5xcl5dqmsprns@liskov>
	<20240227015028.knohvy3spaqwk7lf@liskov>
	<20240227142230.nu3ytvcjwouvczlt@liskov>
	<[email protected]>
	<CAAKRu_ar_C+RCMV_LrCL10ccWA0n-0rZcxfhL67hXFqREpPRfg@mail.gmail.com>
	<[email protected]>

On 2/28/24 15:56, Tomas Vondra wrote:
>> ...
> 
> Sure, I can do that. It'll take a couple hours to get the results, I'll
> share them when I have them.
> 

Here are the results with only patches 0001 - 0012 applied (i.e. without
the patch introducing the streaming read API, and the patch switching
the bitmap heap scan to use it).

The changes in performance don't disappear entirely, but the scale is
certainly much smaller - both in the complete results for all runs, and
for the "optimal" runs that would actually pick bitmapscan.

FWIW I'm not implying the patch must 100% maintain the current behavior,
or anything like that. At this point I'm more motivated to understand if
this change in behavior is expected and/or what this means for users.

regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Attachments:

  [application/pdf] bitmapscan-refactoring-results-optimal.pdf (174.1K, ../[email protected]/2-bitmapscan-refactoring-results-optimal.pdf)
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  [application/pdf] bitmapscan-refactoring-results.pdf (479.9K, ../[email protected]/3-bitmapscan-refactoring-results.pdf)
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