Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hsIiG-0001iY-B4 for pgsql-hackers@arkaria.postgresql.org; Tue, 30 Jul 2019 03:22:08 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.89) (envelope-from ) id 1hsIiE-0001FI-Il for pgsql-hackers@arkaria.postgresql.org; Tue, 30 Jul 2019 03:22:06 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hsIiE-0001Eu-72 for pgsql-hackers@lists.postgresql.org; Tue, 30 Jul 2019 03:22:06 +0000 Received: from mail-qk1-x742.google.com ([2607:f8b0:4864:20::742]) by magus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hsIiA-0007rf-LS for pgsql-hackers@postgresql.org; Tue, 30 Jul 2019 03:22:05 +0000 Received: by mail-qk1-x742.google.com with SMTP id t8so45587694qkt.1 for ; Mon, 29 Jul 2019 20:22:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=2ndquadrant-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:mime-version:content-disposition :content-transfer-encoding:in-reply-to:user-agent; bh=lF7DaT6+OaBRj9o/temHU5y3mGWNzZjKPIgq4wbPfTc=; b=lGBWlyYygRO0dkqG65a555CdQtrFLLUOq5aO47R3SrHsM+9bDGjBjiOB9wd5SfcDqh 3BSop4yeiSQ265SYOEJbM73FVk6i261sxe8fWxbp8+8Mm4GbWnz8VRkFZQmI9OBYeNyU 0osIkyODa6PbhP+LhuoLn7ibsowPF0Jt5C8TlSqeQ4vHxSWiEHi/SrvN/AW6HOAGw24d x2lL0KgGCOgeQANhXc4rQ2n4X4ACFF+04/2ZzXR4sAOfPWCUXx853jVcy6X8uJKWMnUW DY9zq2KgHREAf13LQNctVQJ8Xh2g8PhOqHWj9LsrAIURNEULCiAe7t4/a+yUrzUBQ8ut HU6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=lF7DaT6+OaBRj9o/temHU5y3mGWNzZjKPIgq4wbPfTc=; b=U4BdkMfGs75FgJ8jw7O9IF1H/XeVqKVMW4a6xRRc83LHLnF1phv4HdvxXwpzcxgGuv HCsGo88x+2xNCiC8zcWBW7rhDp1Rynw2rN//kueNVrolE7F2skG4w337s4quvbUCB2wt DSE+eI4TDSZATf8xGU6htDoRjZpKYXho1FXhyAPuer8xiEnYZ+DsI32rEqKAOIO4Aryp 8aaq6KZkURA58eSq7oAgPSBuNrGmde1M9sroCyiqSLRSOBQbYmgz8uvujQ9FN0OuLKos eico47r15n1fKhk4C6jKghgM0tLWgV2dEo3BlCRE9DGiQvZ98ZtcEBY8kOpC3J9nEcWQ DLUg== X-Gm-Message-State: APjAAAVS5GX498Odcq/lKNXu2EqDmwjVWFviFl8HT4lWSewty4ZbNLb0 D4GdyPNoK+D9Lbcd5aF3XtuKBA== X-Google-Smtp-Source: APXvYqx96Z3UPDxjOr2LP0byY834z3WlTvBTM74d5c8dmBb+kuvWV2veOCSZo8qS4sAmfmDBb+2MQA== X-Received: by 2002:ae9:e845:: with SMTP id a66mr74280027qkg.451.1564456920179; Mon, 29 Jul 2019 20:22:00 -0700 (PDT) Received: from nimloth.alvh.no-ip.org ([201.186.81.5]) by smtp.gmail.com with ESMTPSA id z50sm33204518qtz.36.2019.07.29.20.21.59 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 29 Jul 2019 20:21:59 -0700 (PDT) Received: by nimloth.alvh.no-ip.org (Postfix, from userid 1000) id 1277D120D2C; Mon, 29 Jul 2019 23:21:57 -0400 (-04) Date: Mon, 29 Jul 2019 23:21:57 -0400 From: Alvaro Herrera To: Tom Lane Cc: Robert Haas , Michael Paquier , Andres Freund , PostgreSQL Hackers Subject: Re: TopoSort() fix Message-ID: <20190730032157.GA652@alvherre.pgsql> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3243.1564437314@sss.pgh.pa.us> User-Agent: Mutt/1.9.4 (2018-02-28) List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk On 2019-Jul-29, Tom Lane wrote: > FYI, I just got done inventing a way to reach that code, and I have > to suspect that it's impossible to do so in production, because under > ordinary circumstances no parallel worker will take any exclusive lock > that isn't already held by its leader. Hmm, okay, so this wasn't a bug that would have bit anyone in practice, yeah? That's reassuring. Thanks, -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services