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 1g7AEp-00030P-Fk for pgsql-hackers@arkaria.postgresql.org; Tue, 02 Oct 2018 02:16:39 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.89) (envelope-from ) id 1g7AEl-0007BK-4y for pgsql-hackers@arkaria.postgresql.org; Tue, 02 Oct 2018 02:16:35 +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 1g7AEk-0007BC-QI for pgsql-hackers@lists.postgresql.org; Tue, 02 Oct 2018 02:16:34 +0000 Received: from out3-smtp.messagingengine.com ([66.111.4.27]) by makus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.89) (envelope-from ) id 1g7AEi-0004Ku-A2 for pgsql-hackers@lists.postgresql.org; Tue, 02 Oct 2018 02:16:33 +0000 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.nyi.internal (Postfix) with ESMTP id 9790B21785; Mon, 1 Oct 2018 22:16:31 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute4.internal (MEProxy); Mon, 01 Oct 2018 22:16:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paquier.xyz; h= cc:content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to:x-me-sender:x-me-sender:x-sasl-enc; s= fm2; bh=piq6ENI2VjaXsJdL6PjpMgCaX2xokT9DeF6FSQrdDPk=; b=eeJvVTfq ZzAhaeEu2xpE0eKL8MFd4AUSIgf5Ksl/Ci08kOrRpsTXv7uL3V9T/ntMUWp0CwS7 TA+LhH+MogK7xYqk8MIVDMuZv/y5KPt63VH6ZzYSfBE8vtI1B9Z2X3fr0xPDhnUN 0BMb0zcseh/2vz88gu5HJEQLlqQzzvIvksvUQk/JPKBwuEAsYbCHjcunHpXx2i/m 0FhTXTZAU88mYQ1R4++QvLQE5hThLPtBejoxqoMji3Nl94YfgEcpk9GarVi/nFXr 1/8HkhRDsrkTR/42fIcAIl2jTMCob91NXOyzBu/fEBpP+l5TfN4GbgZJOYgzAyO4 nOdMX4GMtV4kOw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc: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=piq6ENI2VjaXsJdL6PjpMgCaX2xok T9DeF6FSQrdDPk=; b=mlh1h3qOcqK/GHFOnTuX5FusUtOr4UKNldOO/O/HQloHA ksHfJ+/4rBySPvAAnCaUsCCwoYlpXFb6fCq3xDE0lWCQJm6++3BGggrA+uxE3Oqe J1I69/vbl0KW5SRiH925AyQyKsTaoI0Q5EyQWr1M4EAq2Bm1c+yGwZxhgkk9cUl0 wVXaCis+VGMDjODfCJrDOJPiWkbqKsKKBfgWskqWlBPLcfccKlGcrQ/ccUgkNZ6K BeTeSkmoX/N/CEtupiw5C+rNE1NAxlHq1PwGCnx1tzF1r/ib/YlVkylcwTWYh1Er SyuuvYZQ4A11DoZgCFsm18jMZRkXH77v8JqEbFgCA== X-ME-Sender: X-ME-Proxy: Received: from paquier.xyz (c137162.net61215.cablenet.ne.jp [61.215.137.162]) by mail.messagingengine.com (Postfix) with ESMTPA id 8B701E4179; Mon, 1 Oct 2018 22:16:29 -0400 (EDT) Date: Tue, 2 Oct 2018 11:16:26 +0900 From: Michael Paquier To: Gavin Flower Cc: pgsql-hackers@lists.postgresql.org Subject: Re: POC: GROUP BY optimization Message-ID: <20181002021626.GF11712@paquier.xyz> References: <523d1f60-c60c-5c8c-8cc5-c6c078970da6@2ndquadrant.com> <24c773b8-3a9a-8fe9-610d-01145758931b@sigaev.ru> <623f5e50-eeb2-1279-d30b-dc43611fb063@2ndquadrant.com> <1913e082-0d8d-5eb8-c8ca-053af828076a@2ndquadrant.com> <3bbdd1ee-544d-a549-b0c2-30485d9f6a16@sigaev.ru> <83b0d707-405d-c2be-0d98-01267e68d671@2ndquadrant.com> <0b3ee377-2f67-f58d-6177-bc2ed4626499@archidevsys.co.nz> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="eN+VsUY52o/CFM+1" Content-Disposition: inline In-Reply-To: <0b3ee377-2f67-f58d-6177-bc2ed4626499@archidevsys.co.nz> List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk --eN+VsUY52o/CFM+1 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Jun 30, 2018 at 09:19:13AM +1200, Gavin Flower wrote: > Additionally put an upper limit threshold on the number of combinations to > check, fairly large by default? >=20 > If first threshold is exceeded, could consider checking out a few more > selected at random from paths not yet checked, to avoid any bias caused by > stopping a systematic search.=A0 This might prove important when N! is fa= irly > large. Please note that the latest patch available does not apply, so this has been moved to next CF 2018-11, waiting for input from its author. -- Michael --eN+VsUY52o/CFM+1 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEG72nH6vTowiyblFKnvQgOdbyQH0FAluy1PoACgkQnvQgOdby QH3eqxAApjp7oFzBWow6YOtXqF1wUEUZyjcYHbzOAqFzfnHJc39aEguiRG+huYzq BLuqWEFWNBI4UIIEcZfPfm2tHDu/8mJB1VX14qjb6dUMq+F1Y8Pqrt00McHPBLmE 4izTkArlg31q/HdK9I3ppNR2pYaaEJibzxDB4GE++APqPoajy4BMJq6MoL1HlxJs UzKEEGMt+ADCyzmXl67fhsj6D8wHJ0LxC7P5EeDMCJHc/StYge1pRt3BR9zRwZll iGRd2nC2Wjwhbjq3qw+sR0d+QRUt3DsZw2otnBg/60+Dx4JWObbyjZF4oKWuNy3B 75xqwvyPjbHx15Qa8xqlHTloH0d1nJ5oxl5f+4ADGk+S7vl35RknezTpsNycQbN1 L6905OqSyyc6IOGjFbpAXrcU4Rcm2UHo8o9/i+u9g9rt56SuZit+NeGXMcthLqg9 qiWMN8KLXYGMSx05pgZJDb1CWA774SV6nLOaZUEkiEmFRrCYxJyJ4tJyqOUDgSUR jgr+hkSwo/0B+FVrmDFjRZF/MbhZr3bUu7twBkY+NLYPjnuugywZaKmH4h389/gl QDwpO0Ap+OUYndG8OVCEh7R2KZqgtYanpck4DirqFRmYBSxFaKev9KufFbDf/tDV XRH7+GAEZwEh9IIqmaN5NQIXrmlftPe1niYhixBDsAzyrdVNRTo= =TuNq -----END PGP SIGNATURE----- --eN+VsUY52o/CFM+1--