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 1vvzsQ-00EZmr-0a for pgsql-performance@arkaria.postgresql.org; Fri, 27 Feb 2026 15:35:38 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.96) (envelope-from ) id 1vvzsO-004OwI-2f for pgsql-performance@arkaria.postgresql.org; Fri, 27 Feb 2026 15:35:36 +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 1vvzsO-004Ow3-1g for pgsql-performance@lists.postgresql.org; Fri, 27 Feb 2026 15:35:36 +0000 Received: from mail-wm1-x333.google.com ([2a00:1450:4864:20::333]) by makus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.98.2) (envelope-from ) id 1vvzsL-00000001WFr-2z2J for pgsql-performance@postgresql.org; Fri, 27 Feb 2026 15:35:35 +0000 Received: by mail-wm1-x333.google.com with SMTP id 5b1f17b1804b1-4836f363ad2so25227425e9.1 for ; Fri, 27 Feb 2026 07:35:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1772206533; x=1772811333; darn=postgresql.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=RGdHRTZ0yCXbWFyeLmYTR4V0aW2+WyC5WC6HOVHS7dE=; b=mswu6ulVFtyRzKRqjdxK2jAOvpTPXNQRD/NHzEue8ef7jki8To9InZEbt4XKoTGrFC wv6kGqB3DXXTAk4hjslFUU716MbROvSd6UXj9gnSUqjPwhajl3+2tkpOhY+w5FEKtW9n PXuWz1M/0sn/0IF9hiF2Q6V6RQhEI1GDA7Cu2PT8NXUyHkFelECw59i9j7bF/oRXvuzr /AjyUZYYdUH+LCRkZTt2bnVsVLCOI8yOx6GFDJ4pCRxNq5wnAISphkR7RifprFoQiUFD Y/zwqum5gd8xWW5tI+TwLjGCpERbmDMLNpIiF6ROxIysiG3A4FMemv1f+aEoQGBEXerZ E4Dg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772206533; x=1772811333; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=RGdHRTZ0yCXbWFyeLmYTR4V0aW2+WyC5WC6HOVHS7dE=; b=aEcJ+uO+binQ3ZNwW9KgWZyY9wu84jyW+je928a9Nk4fwq2ZcQu3U1ipEOhbHoEs2q n4o1ES2iDYXsn9tlotor+KEnmhozBYuHZx2xb2obhiMjYObMKZ4lC867BF8nigJrAZbF Bx96UxyYPQQXWaciJbykwRa2qXEC/c4uoDe2We78X2dBM89JQq4cVH5MrshRSRK+PWWW Gzyuwm9HMyVSRrEJ6+9IhWAecFD+c2dswJXThdU97dpwR/UCUJ4gBmcyHEPQLsJg74rI ybY0vu6iViq1Ks+hhtIpyWG36yZPd2xlux77kWNRxIU3X7uJ9BDBpAbLs6Gp9lawv4Nl 95vw== X-Gm-Message-State: AOJu0YwKR2RbvVpDIWxmwDYHmNhtr0viKAD01641YKoQygbNXH91A0/+ hnN/9tsrK1N6ImUWdKoYnvZ6SnwpREA5F4E2ZTF5cdjjHhvK75l/7q1J X-Gm-Gg: ATEYQzxiqHTG6qqFVxHDAwJrD7ZtyA45gJy2Oyli66yU924LgV8w7BIytwtqvPQ7XWC 7C1rNE+ylqjImzt0Z6CHJnZ5T4sgmyhI9IRtcGt1RdXKCoYql1gTJc3eE01tg1r84s2K1/XgjBn J5aH6JB7c17cCnNagC0O8rMNo7LfpP41ZQCewiMaZDNy53UaqkT6djTTEgwzBNpjSuUzy/3ikEX XOCNS5amu7Lxsaapye/YMKZg5XkSTK0zU45Dpg5qOQCX/XyNyj1Chfen181kNdn23jtWpT15Xdd /V3rqzGGm9w7KpHXv75pi7TVDMGQFHtSuifgc0VMp3BK5Bv0IywilESa0YS/5scDMfT29ZpsIJa eCDHV1VXa6HH6DuXF68TbOvGGADdop1N3fM3ct8K/e7I2drkxDxGvMIVqzq0jgpM1F85RSlBFBx qG3xI2blbV6AXQO0Jk69+RTqo199UfGRjEgGlgtrVrr1gPMNyN X-Received: by 2002:a05:600c:4744:b0:477:93f7:bbc5 with SMTP id 5b1f17b1804b1-483c9bc03d1mr50914775e9.10.1772206533172; Fri, 27 Feb 2026 07:35:33 -0800 (PST) Received: from [192.168.15.167] ([80.251.191.198]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483c3b44207sm121335685e9.7.2026.02.27.07.35.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 Feb 2026 07:35:32 -0800 (PST) Message-ID: <091eef0e-0271-47d1-aa47-439284e3f316@gmail.com> Date: Fri, 27 Feb 2026 16:35:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: unstable query plan on pg 16,17,18 To: Attila Soki , Laurenz Albe Cc: pgsql-performance@postgresql.org References: <64ddfe83-317c-4cf1-b04f-cb74d9f40629@gmail.com> <529E2365-6C3F-4BDA-9625-312F3A023C5B@gmx.net> <5bace3e5-3d6b-4f81-92a9-9ff4e9e5de53@gmail.com> <1C445A2F-3256-4F04-B55D-9850581FF39A@gmx.net> <0dd76506-053e-4a30-9f95-9dc324e8e1fb@gmail.com> <1388B912-7E9A-475A-93AA-67FB99A084BC@gmx.net> <0c8b9845-a2ac-4613-8075-45dc55911143@gmail.com> <45AA83DB-A6B4-43A2-879B-290E4A7845AE@gmx.net> <4FEE2E28-5A05-4423-B49E-CA23E2B78420@gmx.net> <6199d929-711e-4657-bcf9-7d285cbafca6@gmail.com> <24F30E2F-038C-4E3D-A8AA-1C8EAAF2E547@gmx.net> Content-Language: en-US From: Andrei Lepikhov In-Reply-To: <24F30E2F-038C-4E3D-A8AA-1C8EAAF2E547@gmx.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk On 27/2/26 16:00, Attila Soki wrote: > On 27 Feb 2026, at 09:15, Andrei Lepikhov wrote: > I dont know the inner workings of analyze, is that normal that executing > analyze on unchanged data can flip the plan? Does analyze select a > random set of rows? Yes, this is completely normal because ANALYZE works in a random way. You can try using the Join-Order-Benchmark to see how running the ANALYZE command can change the execution time of the same query, sometimes by as much as ten times. -- regards, Andrei Lepikhov, pgEdge