Received: from malur.postgresql.org ([2a02:16a8:dc51::56]) by arkaria.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.89) (envelope-from ) id 1g0MSy-0007dM-QW for pgsql-hackers@arkaria.postgresql.org; Thu, 13 Sep 2018 07:55:09 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.89) (envelope-from ) id 1g0MSw-0007NW-Pt for pgsql-hackers@arkaria.postgresql.org; Thu, 13 Sep 2018 07:55:06 +0000 Received: from makus.postgresql.org ([2001:4800:1501:1::229]) by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.89) (envelope-from ) id 1g0MSw-0007NP-Fj for pgsql-hackers@lists.postgresql.org; Thu, 13 Sep 2018 07:55:06 +0000 Received: from wout2-smtp.messagingengine.com ([64.147.123.25]) by makus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.89) (envelope-from ) id 1g0MSp-0004TF-7Q for pgsql-hackers@postgresql.org; Thu, 13 Sep 2018 07:55:05 +0000 Received: from compute7.internal (compute7.nyi.internal [10.202.2.47]) by mailout.west.internal (Postfix) with ESMTP id 6BBED402; Thu, 13 Sep 2018 03:54:57 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute7.internal (MEProxy); Thu, 13 Sep 2018 03:54:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=FrLkjH 3E85l5tlHdy5ZdVIXpNaWnR/NzAp3uQD+UbsA=; b=dPl+qNey6Bj9PRtVbp9Pwz FEKzyblCc9diTbYKNpbBBXph3GI985UrL+Qitn9Q1aprbPNPdwNLDFZW6BrZyYRh 4d+9bZGJxMLR0+rDPKon+ssFURCeTENtEZkQPQ6RngDAH73yJbrkNGW5TiI1ewAa JIaQ9rALnJqQpsAsNZJg0zASA9WjOivKmYp+cX7LLi1NRZTFV2Q24usoq/o6l7Rt 0AHzUMwjLGjT2U3tGXo4zaz1GmEi9SMnefs278Yq+CJTHjPQWjY3ulEkpTmcrioT Jmw3Jf59I483d4JM7tdqNVH+o0OFAe7C0kk1hX/ihEWJKcLH2gYteMA24SiVyh5g == X-ME-Proxy: X-ME-Sender: Received: from april.pezone.net (p5df2a2d9.dip0.t-ipconnect.de [93.242.162.217]) by mail.messagingengine.com (Postfix) with ESMTPA id 62172102A0; Thu, 13 Sep 2018 03:54:55 -0400 (EDT) Subject: Re: pg_dump test instability To: Tom Lane References: <5137fe12-d0a2-4971-61b6-eb4e7e8875f8@2ndquadrant.com> <32399.1535379095@sss.pgh.pa.us> <20180827144138.GO3326@tamriel.snowman.net> <1665.1535381158@sss.pgh.pa.us> <20180827155943.GP3326@tamriel.snowman.net> <1765.1535482037@sss.pgh.pa.us> <406b7f39-039d-6cfc-6d36-ee797d214af7@2ndquadrant.com> <6771.1536768395@sss.pgh.pa.us> Cc: Stephen Frost , pgsql-hackers From: Peter Eisentraut Openpgp: preference=signencrypt Autocrypt: addr=peter.eisentraut@2ndquadrant.com; 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Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <6771.1536768395@sss.pgh.pa.us> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk On 12/09/2018 18:06, Tom Lane wrote: > No. In both code paths, the array slot at index first_te is being > physically dropped from the set of valid entries (by incrementing > first_te). In the first path, that slot holds the item we want to > remove logically from the set, so that incrementing first_te is > all we have to do: the remaining entries are still in the range > first_te..last_te, and they're still sorted. In the second code > path, the item that was in that slot is still wanted as part of > the set, so we copy it into the valid range (overwriting the item > in slot i, which is no longer wanted). Now the valid range is > probably not sorted, so we have to flag that a re-sort is needed. I see. Why not shift all items up to the i'th up by one place, instead of moving only the first one? That way the sortedness would be preserved. Otherwise we'd move the first one into the middle, then sorting would move it to the front again, etc. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services