Received: from malur.postgresql.org ([217.196.149.56])
	by arkaria.postgresql.org with esmtps
 (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256)
	(Exim 4.92)
	(envelope-from <pgsql-performance-owner+archive@lists.postgresql.org>)
	id 1m6bXI-0004S0-GO
	for pgsql-performance@arkaria.postgresql.org; Thu, 22 Jul 2021 16:27:00 +0000
Received: from localhost ([127.0.0.1] helo=malur.postgresql.org)
	by malur.postgresql.org with esmtp (Exim 4.92)
	(envelope-from <pgsql-performance-owner+archive@lists.postgresql.org>)
	id 1m6bXH-0003xr-G2
	for pgsql-performance@arkaria.postgresql.org; Thu, 22 Jul 2021 16:26:59 +0000
Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29])
	by malur.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256)
	(Exim 4.92)
	(envelope-from <tgl@sss.pgh.pa.us>)
	id 1m6bXH-0003xe-7n
	for pgsql-performance@lists.postgresql.org; Thu, 22 Jul 2021 16:26:59 +0000
Received: from sss.pgh.pa.us ([66.207.139.130])
	by magus.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256)
	(Exim 4.92)
	(envelope-from <tgl@sss.pgh.pa.us>)
	id 1m6bXE-0000zb-MN
	for pgsql-performance@postgresql.org; Thu, 22 Jul 2021 16:26:58 +0000
Received: from sss1.sss.pgh.pa.us (localhost [127.0.0.1])
	by sss.pgh.pa.us (8.15.2/8.15.2) with ESMTP id 16MGQogo786911;
	Thu, 22 Jul 2021 12:26:50 -0400
From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
cc: "ldh@laurent-hasson.com" <ldh@laurent-hasson.com>,
        Peter Geoghegan <pg@bowt.ie>, Justin Pryzby <pryzby@telsasoft.com>,
        "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Big performance slowdown from 11.2 to 13.3
In-reply-to: <786600.1626970898@sss.pgh.pa.us>
References: 
 <MN2PR15MB25601E80A9B6D1BA6F592B1985E39@MN2PR15MB2560.namprd15.prod.outlook.com>
 <20210721191528.GC19620@telsasoft.com>
 <MN2PR15MB256016E33F00DE60B96F02D385E39@MN2PR15MB2560.namprd15.prod.outlook.com>
 <CAH2-Wzm3rSAWHyENb3T0X8M_qdYjF1t7rntkMJ2kDiuhVOHx3g@mail.gmail.com>
 <MN2PR15MB2560C1A890DC07F9359FB56285E39@MN2PR15MB2560.namprd15.prod.outlook.com>
 <732758.1626911007@sss.pgh.pa.us>
 <MN2PR15MB2560778595BB7AF6E691B26785E39@MN2PR15MB2560.namprd15.prod.outlook.com>
 <MN2PR15MB2560D429866BD65A70574A6C85E49@MN2PR15MB2560.namprd15.prod.outlook.com>
 <CAApHDvqoF7y7SQjGT=940njnAd_CUcUG6oRYChcP_+eJyuNiug@mail.gmail.com>
 <MN2PR15MB25603D3CE06C8F9C312EA58985E49@MN2PR15MB2560.namprd15.prod.outlook.com>
 <MN2PR15MB2560E4574A6E2B5AED2C03CB85E49@MN2PR15MB2560.namprd15.prod.outlook.com>
 <784576.1626968702@sss.pgh.pa.us> <785218.1626969409@sss.pgh.pa.us>
 <CAApHDvo+Gb80BVPKYCwHbLa7a7ZXp9ziq9URrpQaKdvXsd46bg@mail.gmail.com>
 <786600.1626970898@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Thu, 22 Jul 2021 12:21:38 -0400"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <786909.1626971210.1@sss.pgh.pa.us>
Date: Thu, 22 Jul 2021 12:26:50 -0400
Message-ID: <786910.1626971210@sss.pgh.pa.us>
List-Id: <pgsql-performance.lists.postgresql.org>
List-Help: <https://lists.postgresql.org/manage/>
List-Subscribe: <https://lists.postgresql.org/manage/>
List-Post: <mailto:pgsql-performance@lists.postgresql.org>
List-Owner: <mailto:pgsql-performance-owner@lists.postgresql.org>
List-Archive: <https://www.postgresql.org/list/pgsql-performance>
Archived-At: 
 <https://www.postgresql.org/message-id/786910.1626971210%40sss.pgh.pa.us>
Precedence: bulk

I wrote:
> I think the right fix here is to remove the cap, which will require
> changing get_hash_mem to return double, and then maybe some cascading
> changes --- I've not looked at its callers.

Or, actually, returning size_t would likely make the most sense.
We'd fold the 1024L multiplier in here too instead of doing that
at the callers.

			regards, tom lane