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 1nCH4I-0008TW-69 for pgsql-hackers@arkaria.postgresql.org; Tue, 25 Jan 2022 08:20:46 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.92) (envelope-from ) id 1nCH4H-00044h-1B for pgsql-hackers@arkaria.postgresql.org; Tue, 25 Jan 2022 08:20:45 +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 1nCH4G-00044Y-N1 for pgsql-hackers@lists.postgresql.org; Tue, 25 Jan 2022 08:20:44 +0000 Received: from mail-pj1-x1036.google.com ([2607:f8b0:4864:20::1036]) by magus.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1nCH4E-0001WM-AN for pgsql-hackers@lists.postgresql.org; Tue, 25 Jan 2022 08:20:44 +0000 Received: by mail-pj1-x1036.google.com with SMTP id g11-20020a17090a7d0b00b001b2c12c7273so1136324pjl.0 for ; Tue, 25 Jan 2022 00:20:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=BDqiMknxsSdhx5FaF5k8e8Vd0WwS1W3eeW12VKqf8fM=; b=nR4SqNyap9WcQ2rvwbZXE/CSJdpi7tIqB5jYpEJ5+fveC28j5gB5JIcuujwhS6J/5A rOZKFZ/B5BGDSEXvgLe8/df0sxBBNoGjmi6XnDH67lbQ0pkr5Y9X/dLsU1iAvPC18C52 3FJ3r3TGEfbrr1nGiopIKIvTZWdJXojQxLWPxHqO0li47eYXC8WSa4u385h5bqosD/wG OSknDBXeZ46Y5Q/28kaTB0MPlo4JmLPdiT5DLhA6mKfm00lhIZAA4EOrIZURJ2ZoTG4m BJg+fMhl/yHvoRBOEt0kof1WP6oRxN1yNHsbkMQ5283I30m8XPM5TzNisngtJiv8nJCj H/jQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=BDqiMknxsSdhx5FaF5k8e8Vd0WwS1W3eeW12VKqf8fM=; b=jPdBB0EXmWoB104xbWGbbxZX2c4JzPvDiS2cXl1OhGYUSPhLYTWASUvlYzb2ogJWvl rfzu31QmwGgGVSE0LJL0FOnQLiQulI8j8UDDbpvSicbiZheZs0LlcW0kZXEtHxV6qPVg L0iNaPYmAKOG9rKSESVvCbUcndi9AehllFuaE2KH4QSqAf9JAkCD6PNgUzhLWoz2h8lW 5OHm16VhTTWyLInimuKxGtXSPAOHNdfBmTg+HO1+A6sKix2yit6AfVpWAgTI7EHb4GV9 ezYxg640SbnmDZisbUI3iq7hYaATGqANmL6yiIXJPtDab/79HCoI6zSNLNmKBEaH8bTg tLEw== X-Gm-Message-State: AOAM531Cpu7T/eR+vjSL/Zem6yC9sEO3Gk+jS3Uppof0ilm3pbhOiecG 7VKs5D5OeAwpEqYjW2Qu8uvYpFJmkP4/nzPU+D8wrV4E X-Google-Smtp-Source: ABdhPJyBG3eQaOd9C39E5kLgf1NJckMBKVjWkKugjTOk1css5vfNKJzqtRLsiFE2jOsasX6Rwk6YE8Jc9FhP0QFEvrI= X-Received: by 2002:a17:90b:4b01:: with SMTP id lx1mr2120423pjb.52.1643098839531; Tue, 25 Jan 2022 00:20:39 -0800 (PST) MIME-Version: 1.0 References: <382c3b52071a087fd4357e22959b3ddb05e524b7.camel@postgrespro.ru> In-Reply-To: From: David Rowley Date: Tue, 25 Jan 2022 21:20:25 +1300 Message-ID: Subject: Re: Fix BUG #17335: Duplicate result rows in Gather node To: Yura Sokolov Cc: PostgreSQL Developers Content-Type: text/plain; charset="UTF-8" List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk On Tue, 25 Jan 2022 at 20:03, David Rowley wrote: > > On Tue, 25 Jan 2022 at 17:35, Yura Sokolov wrote: > > And another attempt to fix tests volatility. > > FWIW, I had not really seen the point in adding a test for this. I > did however see a point in it with your original patch. It seemed > useful there to verify that Gather and GatherMerge did what we > expected with 1 worker. I ended up pushing just the last patch I sent. The reason I didn't think it was worth adding a new test was that no tests were added in the original commit. Existing tests did cover it, but here we're just restoring the original behaviour for one simple case. The test in your patch just seemed a bit more hassle than it was worth. I struggle to imagine how we'll break this again. David