Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Wg13N-0004Ex-AF for pgsql-performance@arkaria.postgresql.org; Fri, 02 May 2014 00:10:13 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1Wg13M-0001l7-PS for pgsql-performance@arkaria.postgresql.org; Fri, 02 May 2014 00:10:12 +0000 Received: from makus.postgresql.org ([2001:4800:7903:4::125]) by malur.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Wg13L-0001kZ-FK for pgsql-performance@postgresql.org; Fri, 02 May 2014 00:10:11 +0000 Received: from prod2.officenet.no ([195.159.87.246]) by makus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Wg13H-00083r-6F for pgsql-performance@postgresql.org; Fri, 02 May 2014 00:10:10 +0000 Received: from localhost ([127.0.0.1] helo=prod2) by prod2.officenet.no with esmtp (Exim 4.76) (envelope-from ) id 1Wg13F-0000zO-MK for pgsql-performance@postgresql.org; Fri, 02 May 2014 02:10:05 +0200 Date: Fri, 2 May 2014 02:10:05 +0200 (CEST) From: Andreas Joseph Krogh To: pgsql-performance@postgresql.org Message-ID: In-Reply-To: Subject: Re: Optimize query for listing un-read messages MIME-Version: 1.0 X-Mailer: OfficeNet Mail 1.9.0-SNAPSHOT X-Pg-Spam-Score: -1.9 (-) Content-Type: multipart/related; boundary="----=_Part_81_1891264369.1398989405504" List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-performance Precedence: bulk Sender: pgsql-performance-owner@postgresql.org ------=_Part_80_2052660711.1398989405503 Content-Type: multipart/related; boundary="----=_Part_81_1891264369.1398989405504" ------=_Part_81_1891264369.1398989405504 Content-Type: multipart/alternative; boundary="----=_Part_82_1553062569.1398989405522" ------=_Part_82_1553062569.1398989405522 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable P=C3=A5 fredag 02. mai 2014 kl. 01:58:04, skrev David G Johnston < david.g.johnston@gmail.com >:=20 Per-User caching does seem to be something that is going to be needed... Depending on how many users are being tracked would storing the "reader_id= " in an indexed array improve matters?=C2=A0 " SELECT ... FROM message WHERE= NOT (1 =3D ANY(reader_ids)) ; UPDATE message SET reader_ids =3D reader_ids || 1 W= HERE messageid =3D ..."=C2=A0 I'm not that familiar with how well indexes over = arrays work or which kind is needed (i.e. gin/gist). =C2=A0 =C2=A0 "is_read" is o= ne of many=20 properties being tracked for a message... =C2=A0 =C2=A0 =E2=80=8BBut you do= n't have to have all=20 of them on the same table. =C2=A0Once you've identified the messages in que= stion=20 performing a standard join onto a supplemental detail table should be fairl= y=20 straight-forward. =C2=A0 Do these other properties have values when "is_rea= d" is=20 false or only when "is_read" is true? =C2=A0Since you already allow for the= =20 possibility of a missing record (giving it the meaning of "not read")=E2=80= =8B these=20 other properties cannot currently exist in that situation. =C2=A0 =C2=A0 A = message might=20 hold a property (ie. is_important) when is_read is FALSE (it might be set b= ack=20 to is_read=3DFALSE after being read the first time). =C2=A0 -- Andreas Josp= eh Krogh=20 CTO / Partner - Visena AS Mobile: +47 909 56 963 andreas@visena.com=20 www.visena.com =20 =C2=A0 ------=_Part_82_1553062569.1398989405522 Content-Type: text/html;charset=UTF-8 Content-Transfer-Encoding: quoted-printable
P=C3=A5 fredag 02. mai 2014 kl. 01:58:04, skrev David G Johnston <<= a href=3D"mailto:david.g.johnston@gmail.com" target=3D"_blank">david.g.john= ston@gmail.com>:

Per-User caching does seem to be something that is going to be needed...
Depending on how many users are being tracked would storing the "reade= r_id"
in an indexed array improve matters?=C2=A0 " SELECT ... FROM message W= HERE NOT (1
=3D ANY(reader_ids)) ; UPDATE message SET reader_ids =3D reader_ids || 1 WH= ERE
messageid =3D ..."=C2=A0 I'm not that familiar with how well indexes o= ver arrays
work or which kind is needed (i.e. gin/gist).
=C2=A0
=C2=A0
"is_read" is one of many properties being tracked for a mess= age...
=C2=A0
=C2=A0
=E2=80=8BBut you don't have to have all of them on the same table. =C2= =A0Once you've identified the messages in question performing a standard jo= in onto a supplemental detail table should be fairly straight-forward.
=C2=A0
Do these other properties have values when "is_read" is false = or only when "is_read" is true? =C2=A0Since you already allow for= the possibility of a missing record (giving it the meaning of "not re= ad")=E2=80=8B these other properties cannot currently exist in that si= tuation.
=C2=A0
=C2=A0
A message might hold a property (ie. is_important) when is_read is FAL= SE (it might be set back to is_read=3DFALSE after being read the first time= ).
=C2=A0
--
Andrea= s Jospeh Krogh
CTO / Partner<= /span> - Visena AS
Mobile: +47 90= 9 56 963
3D""
=C2=A0
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