Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1wHjNp-007SdQ-0W for pgsql-hackers@arkaria.postgresql.org; Tue, 28 Apr 2026 14:25:53 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.96) (envelope-from ) id 1wHjNn-0007Uj-31 for pgsql-hackers@arkaria.postgresql.org; Tue, 28 Apr 2026 14:25:51 +0000 Received: from makus.postgresql.org ([2001:4800:3e1:1::229]) by malur.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1wHjNn-0007Ub-1g for pgsql-hackers@lists.postgresql.org; Tue, 28 Apr 2026 14:25:51 +0000 Received: from relay1-d.mail.gandi.net ([217.70.183.193]) by makus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1wHjNk-00000003CRx-1fBG for pgsql-hackers@postgresql.org; Tue, 28 Apr 2026 14:25:50 +0000 Received: by mail.gandi.net (Postfix) with ESMTPSA id 19C8C3ED2F for ; Tue, 28 Apr 2026 14:25:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=0x48.dk; s=gm1; t=1777386345; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type; bh=4N0pi7EcruQIIA3iaPK4saRHDisc73cqpqrJfSaC6y8=; b=P7XmjFYvkyqiMwvk4s8OAslHVWljB34CR7osaSzJ3dFC3P+bVZkzTabRvaCEBOE3G3/ja/ ziVH2WEbnB21y8m3O/Ktt9p0QWrv3lhUkRRZ96Goc6GEvRoR0HQXOMoDnwNqCeuLoGyLBf XBUBoXpV55lGNeScoUNcUEuKeC8/3wBrvcYlPW4Cn6VEsh+2lOGKJ54Kdk2OkrB/a7TJ8L qUON+mj9vMXpzwx2hGP0bKZ3b9hvYWIw1LddkDTIHTm1bYBYMcOspZz+Kl4kHkrWy6cQeR xIxr6YvtFY0Orupa3FMgd3So20TrrSq855iij5Lz7aXRuMUoi9CSKRB8uwQQNw== Date: Tue, 28 Apr 2026 16:25:43 +0200 (CEST) From: Henrik TJ To: PostgreSQL Hackers Subject: Fix background writer processing locking in README Message-ID: <7ecd1d06-24ab-ec54-127c-93e4ec691b77@0x48.dk> MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="-1463761151-48804996-1777385652=:132942" Content-ID: <7a401550-ab92-ce78-b0d5-9c5bc1f16e3d@0x48.dk> X-GND-Sasl: henrik@0x48.dk X-GND-Cause: dmFkZTElIZ8sEBkSZHD3fBKdgec5HvVKMbm1IesbyVD2JXElEMO/jhoLA84Tc+qqWLpKMoU645PgAMnHIi7hAr9WqXGmWbeBJFaBKoQYkA9iY1ouH06wMkKRE4WSGjs64e+XQOvprBgEROVPjuTVnZ2rspuM+VnHoP0g7bGI2xGpbWR6UlwDLLAgFDa8tn87t9rhH1LLg6WsZrWdjR4s5sVRugr2RYg8WoIgUd7Bn+Q07bhs0yboKfLVdMpVdN4y8PAmz6gm+yMGeTbDlwClWNCYBixHKTHJ64tHYTmtCad800CSNMbrm4EoaUHBolJUzSLsVhab7eQqAYLu8FnOJpF/Yxg2RjkEJIxzhsEmcncBGmeW0Ym0aV/fYu2UBVCDV+eDlHHSUj7FHsXXcBixnEDqT9dIkP7ahzUYFuHAZkGhE7beEyZHk30/5RUgoBrifQ+mYv/S0HR4PficISXZsEJh16deqHWGd7JwAvzwHELZwiqQtseRVBIrxydjwkL5fFNMlP2wskk07QLDh/4X0RUXlQCcPd6hOG+j8gdY88x4H/6izw4vMvsW2ufsEXQE+WUbFpURtczn0NGGy+mAtmyd2PTX3W4n2Yp2ZyCZuKtUirSYXicNMyMpkpqXDNT2ZwMHv5DYEsyJfxUXzVhRF9hfiWlfjisFuPFSl3PjV2/bIlxybw X-GND-State: clean X-GND-Score: -100 List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1463761151-48804996-1777385652=:132942 Content-Type: text/plain; CHARSET=US-ASCII; format=flowed Content-ID: <84522aed-6da1-22d1-26a6-f17e0a994685@0x48.dk> Hi I was reading through src/backend/storage/buffer/README, and the paragraph about writing out buffers seems not to have been updated after starting to use the share-exclusive lock level, commit 82467f627bd4. The paragraph in question: The background writer takes shared content lock on a buffer while writing it out (and anyone else who flushes buffer contents to disk must do so too). This ensures that the page image transferred to disk is reasonably consistent. We might miss a hint-bit update or two but that isn't a problem, for the same reasons mentioned under buffer access rules. The attached patch updates this to use shared-exclusive, and removes the consistency bit. Arguably the entire paragraph could be removed, as the issue is covered earlier in the document, but I tried to keep the doc mostly as-is. best regards, Henrik ---1463761151-48804996-1777385652=:132942 Content-Type: text/plain; CHARSET=US-ASCII; NAME=v1-0001-Update-the-paragraph-on-background-writer-processing.patch Content-Transfer-Encoding: BASE64 Content-ID: <8bcb480d-4fbb-d3e0-8970-16984cd56a7d@0x48.dk> Content-Description: Content-Disposition: ATTACHMENT; FILENAME=v1-0001-Update-the-paragraph-on-background-writer-processing.patch RnJvbSAyNDFiYTRlM2VjZGE2NDIxMTk2YWRkZmYzNzcwNGU4NGEzM2Q1ZTYy IE1vbiBTZXAgMTcgMDA6MDA6MDAgMjAwMQ0KRnJvbTogSGVucmlrIFRKIDxo ZW5yaWtAMHg0OC5kaz4NCkRhdGU6IFR1ZSwgMjggQXByIDIwMjYgMTI6NDA6 MTggKzAyMDANClN1YmplY3Q6IFtQQVRDSF0gVXBkYXRlIHRoZSBwYXJhZ3Jh cGggb24gYmFja2dyb3VuZCB3cml0ZXIgcHJvY2Vzc2luZyBvbg0KIGxvY2tp bmcgdG8gc2F5IHNoYXJlLWV4bHVzaXZlLCBhcyB0aGF0IHNob3VsZCBub3cg YmUgdXNlZCBmb3Igd3JpdGluZywgYW5kDQogcmVtb3ZlIHRoZSBub3RlIG9u IGNvbnNpc3RlbmN5LCBhcyBpdCBpcyBubyBsb25nZXIgcmVsZXZhbnQuDQoN ClByb2JhYmx5IGEgdGlueSBvdmVyc2lnaHQgaW4gODI0NjdmNjI3YmQ0DQot LS0NCiBzcmMvYmFja2VuZC9zdG9yYWdlL2J1ZmZlci9SRUFETUUgfCA4ICsr Ky0tLS0tDQogMSBmaWxlIGNoYW5nZWQsIDMgaW5zZXJ0aW9ucygrKSwgNSBk ZWxldGlvbnMoLSkNCg0KZGlmZiAtLWdpdCBhL3NyYy9iYWNrZW5kL3N0b3Jh Z2UvYnVmZmVyL1JFQURNRSBiL3NyYy9iYWNrZW5kL3N0b3JhZ2UvYnVmZmVy L1JFQURNRQ0KaW5kZXggYjMzMmUwMDJiYTEuLjgwOWFhZjhkMjhiIDEwMDY0 NA0KLS0tIGEvc3JjL2JhY2tlbmQvc3RvcmFnZS9idWZmZXIvUkVBRE1FDQor KysgYi9zcmMvYmFja2VuZC9zdG9yYWdlL2J1ZmZlci9SRUFETUUNCkBAIC0y NjUsMTEgKzI2NSw5IEBAIG9ubHkgbmVlZHMgdG8gdGFrZSB0aGUgbG9jayBs b25nIGVub3VnaCB0byByZWFkIHRoZSB2YXJpYWJsZSB2YWx1ZSwgbm90DQog d2hpbGUgc2Nhbm5pbmcgdGhlIGJ1ZmZlcnMuICAoVGhpcyBpcyBhIHZlcnkg c3Vic3RhbnRpYWwgaW1wcm92ZW1lbnQgaW4NCiB0aGUgY29udGVudGlvbiBj b3N0IG9mIHRoZSB3cml0ZXIgY29tcGFyZWQgdG8gUEcgOC4wLikNCiANCi1U aGUgYmFja2dyb3VuZCB3cml0ZXIgdGFrZXMgc2hhcmVkIGNvbnRlbnQgbG9j ayBvbiBhIGJ1ZmZlciB3aGlsZSB3cml0aW5nIGl0DQotb3V0IChhbmQgYW55 b25lIGVsc2Ugd2hvIGZsdXNoZXMgYnVmZmVyIGNvbnRlbnRzIHRvIGRpc2sg bXVzdCBkbyBzbyB0b28pLg0KLVRoaXMgZW5zdXJlcyB0aGF0IHRoZSBwYWdl IGltYWdlIHRyYW5zZmVycmVkIHRvIGRpc2sgaXMgcmVhc29uYWJseSBjb25z aXN0ZW50Lg0KLVdlIG1pZ2h0IG1pc3MgYSBoaW50LWJpdCB1cGRhdGUgb3Ig dHdvIGJ1dCB0aGF0IGlzbid0IGEgcHJvYmxlbSwgZm9yIHRoZSBzYW1lDQot cmVhc29ucyBtZW50aW9uZWQgdW5kZXIgYnVmZmVyIGFjY2VzcyBydWxlcy4N CitUaGUgYmFja2dyb3VuZCB3cml0ZXIgdGFrZXMgc2hhcmVkLWV4Y2x1c2l2 ZSBjb250ZW50IGxvY2sgb24gYSBidWZmZXIgd2hpbGUNCit3cml0aW5nIGl0 IG91dCAoYW5kIGFueW9uZSBlbHNlIHdobyBmbHVzaGVzIGJ1ZmZlciBjb250 ZW50cyB0byBkaXNrIG11c3QgZG8NCitzbyB0b28pLiBUaGlzIGVuc3VyZXMg dGhhdCB0aGUgcGFnZSBpbWFnZSB0cmFuc2ZlcnJlZCB0byBkaXNrIGlzIGNv bnNpc3RlbnQuDQogDQogQXMgb2YgOC40LCBiYWNrZ3JvdW5kIHdyaXRlciBz dGFydHMgZHVyaW5nIHJlY292ZXJ5IG1vZGUgd2hlbiB0aGVyZSBpcw0KIHNv bWUgZm9ybSBvZiBwb3RlbnRpYWxseSBleHRlbmRlZCByZWNvdmVyeSB0byBw ZXJmb3JtLiBJdCBwZXJmb3JtcyBhbg0KLS0gDQoyLjUzLjANCg0K ---1463761151-48804996-1777385652=:132942--