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 ) id 1o4Xmv-0004O7-US for pgsql-hackers@arkaria.postgresql.org; Fri, 24 Jun 2022 01:07:10 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.92) (envelope-from ) id 1o4Xmu-0004fe-10 for pgsql-hackers@arkaria.postgresql.org; Fri, 24 Jun 2022 01:07:08 +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 ) id 1o4Xms-0004f6-5R for pgsql-hackers@lists.postgresql.org; Fri, 24 Jun 2022 01:07:07 +0000 Received: from out2-smtp.messagingengine.com ([66.111.4.26]) by magus.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1o4Xmo-0006pE-S9 for pgsql-hackers@postgresql.org; Fri, 24 Jun 2022 01:07:05 +0000 Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailout.nyi.internal (Postfix) with ESMTP id E7A5C5C0132; Thu, 23 Jun 2022 21:07:00 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute5.internal (MEProxy); Thu, 23 Jun 2022 21:07:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=anarazel.de; h= cc:cc:content-transfer-encoding:content-type:date:date:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:sender:subject:subject:to:to; s=fm2; t=1656032820; x= 1656119220; bh=T5DI2PAw+9dWJ7ufOM/L03yvId5IGFCYJEZp4wlLXx4=; b=O +OmkHf3TPKkV7thBMInOdwK3JEQEkI+EQeZMK/jXXGCBWehaLIHpgDC9Gd9+N8cC Lrvn0zJH9tX7o6izY1hzs51OpQ2Nyq5ExtS36j/vCKKcFq59g2r+59eydEikvaLt nvIfJoof0l3FPm40pteZ/FNXI1JzokH5h73SXl+JMBDv+KyyIXVxigMseZUXGgTZ jKoAGcANyACeX9S0LzooxdSLILdrnqcwbeis5tpHF712n5M8EjfMV9rQvLpr5ofO fgiUpM4SvTI7UX9ItqFLwLLGZeZeX2z8yaSBQ5gMPiZ4Gd1obr0sChS8EmXfFkCt KYSQZddwHM5gemxJQDQ8A== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:feedback-id:feedback-id:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:sender:subject:subject:to:to:x-me-proxy:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm2; t=1656032820; x= 1656119220; bh=T5DI2PAw+9dWJ7ufOM/L03yvId5IGFCYJEZp4wlLXx4=; b=q faMB5B2WzWGHc6ArF0oEKPUmkQhWEqNVzd64nsiJCQz7Pe/haS9uByTNKccGMSOz NgU5UxQr/er1EqYTl4e+/sNve++hX1cKnKSYX/Og6MXWn3Z+hEyv6COI8RfZ++WM tPM3fqJvqNXEl252AloAaxnxlFzqLNGASgjjnnCqN17DcGA1FpVZ6KldUAWW+xXU JwOkXIxwnZwI+LSMFsLOPS2pmrep+CwUfL8rCaG4Uh/qITNvQNxEA5uqsFC9s91/ XS+L+1jyp+har8k9ccu11epu//SSCUkrkH/7CanAGlgW15O7Kw+pG71cTQY/geVX S1X77MtCUlCaxCrZ3VsGw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvfedrudefkedggeefucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffvvefukfhfgggtugfgjgfhsehtkeertddttdejnecuhfhrohhmpeetnhgu rhgvshcuhfhrvghunhguuceorghnughrvghssegrnhgrrhgriigvlhdruggvqeenucggtf frrghtthgvrhhnpefffeeklefguefffeeuvdeifeetffeivdeukeffieehleffueefteeu feeiueevgfenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhroh hmpegrnhgurhgvshesrghnrghrrgiivghlrdguvg X-ME-Proxy: Feedback-ID: id4a34324:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 23 Jun 2022 21:07:00 -0400 (EDT) Date: Thu, 23 Jun 2022 18:06:48 -0700 To: "Bagga, Rishu" Cc: "pgsql-hackers@postgresql.org" Subject: Re: SLRUs in the main buffer pool - Page Header definitions Message-ID: <20220624010648.6eb6i4cwvkr5f4sb@alap3.anarazel.de> #From: Andres Freund References: <20220622213943.drj7fni2usgo6owy@alap3.anarazel.de> <7B6E31BC-13E0-45FB-AAEC-3BCEDFB5A52C@amazon.com> <20220623212145.vcooepyq4ynrslxo@alap3.anarazel.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: From: Andres Freund List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk Hi, On 2022-06-24 00:39:41 +0000, Bagga, Rishu wrote: > >When do we need to do so? We should never need to figure out whether an > >on-disk block is for an SLRU or something else, without also knowing >which > >relation / SLRU it is in. > > You are correct that we wouldn’t need to rely on the pd_flag bit to > determine page type for any access to a page where we come top down > following the hierarchy. However, for the purpose of debugging “from the > bottom up” it would be critical to know what type of page is being read in a > system with multiple page header types. That doesn't seem to justify using a bit on the page. Wouldn't it suffice to add such information to the BufferDesc? Greetings, Andres Freund