Date: Wed, 18 Mar 2015 14:37:44 +0100 (CET)
From: Andreas Joseph Krogh <andreas@visena.com>
To: pgsql-sql@postgresql.org
Message-ID: <VisenaEmail.3e.a23660ba6b81553b.14c2d1978d6@tc7-visena>
In-Reply-To: <1426684757283.55625@metametrics.co.uk>
Subject: Re: Effective query for listing flags in use by messages in a folder
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P=C3=A5 onsdag 18. mars 2015 kl. 14:19:18, skrev Hector Vass <
hector.vass@metametrics.co.uk <mailto:hector.vass@metametrics.co.uk>>: My=
=20
recommendation is to hold the data as key value pairs not as a table with=
=20
columns for each flag..=C2=A0

=C2=A0

Taking your table message ... and loading into this key value pair table=20
messaage2..

=C2=A0

drop type if exists myflags cascade; create type myflags as=20
enum('is_seen','is_replied','is_forwarded','is_deleted','is_draft','is_flag=
ged');
drop table if exists message2; create table message2( =C2=A0 =C2=A0 folder_=
id integer not=20
NULL, =C2=A0 =C2=A0 msg varchar(200), =C2=A0 =C2=A0 is_flag myflags ); inse=
rt into message2 select=20
folder_id,msg,'is_seen' from message where is_seen is TRUE; insert into=20
message2 select folder_id,msg,'is_replied' from message where is_replied is=
=20
TRUE; insert into message2 select folder_id,msg,'is_forwarded' from message=
=20
where is_forwarded is TRUE; insert into message2 select=20
folder_id,msg,'is_deleted' from message where is_deleted is TRUE; insert in=
to=20
message2 select folder_id,msg,'is_draft' from message where is_draft is TRU=
E;=20
insert into message2 select folder_id,msg,'is_flagged' from message where=
=20
is_flagged is TRUE; =C2=A0 select is_flag from message2 where folder_id=3D1=
 group by 1;
=E2=80=8B work=3D# select is_flag from message2 where folder_id=3D1 group b=
y 1; =C2=A0 is_flag=20
------------ =C2=A0is_seen =C2=A0is_deleted =C2=A0is_replied (3 rows) =C2=
=A0 New messages are=20
inserted into the message-table "all the time" and it seems quite expensive=
 to=20
keep this key-value table updated (which it must be, using triggers). =C2=
=A0 My=20
version returns in sub-millisecond for a folder with > 100K messages in it,=
=20
which I think is not bad, I just don't like the looks of the query and all =
the=20
indexes required. =C2=A0 Thanks for looking into this. =C2=A0 -- Andreas Jo=
seph Krogh CTO=20
/ Partner - Visena AS Mobile: +47 909 56 963 andreas@visena.com=20
<mailto:andreas@visena.com> www.visena.com <https://www.visena.com> =20
<https://www.visena.com> =C2=A0
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<div>P=C3=A5 onsdag 18. mars 2015 kl. 14:19:18, skrev Hector Vass &lt;<a hr=
ef=3D"mailto:hector.vass@metametrics.co.uk">hector.vass@metametrics.co.uk</=
a>&gt;:</div>

<blockquote style=3D"border-left: 1px solid rgb(204, 204, 204); margin: 0pt=
 0pt 0pt 0.8ex; padding-left: 1ex;">
<div id=3D"divtagdefaultwrapper" style=3D"font-size:12pt;color:#000000;back=
ground-color:#FFFFFF;font-family:Calibri,Arial,Helvetica,sans-serif;">
<p style=3D"margin-top: 0px; margin-bottom: 0px;">My recommendation is to h=
old the data as key value pairs not as a table with columns for each flag..=
=C2=A0</p>

<p style=3D"margin-top: 0px; margin-bottom: 0px;">=C2=A0</p>

<p style=3D"margin-top: 0px; margin-bottom: 0px;">Taking your table message=
 ... and loading into this key value pair table messaage2..</p>

<p style=3D"margin-top: 0px; margin-bottom: 0px;">=C2=A0</p>

<div>drop type if exists myflags cascade;</div>

<div>create type myflags as enum('is_seen','is_replied','is_forwarded','is_=
deleted','is_draft','is_flagged');</div>

<div>drop table if exists message2;</div>

<div>create table message2(</div>

<div>=C2=A0 =C2=A0 folder_id integer not NULL,</div>

<div>=C2=A0 =C2=A0 msg varchar(200),</div>

<div>=C2=A0 =C2=A0 is_flag myflags</div>

<div>);</div>

<div>insert into message2 select folder_id,msg,'is_seen' from message where=
 is_seen is TRUE;</div>

<div>insert into message2 select folder_id,msg,'is_replied' from message wh=
ere is_replied is TRUE;</div>

<div>insert into message2 select folder_id,msg,'is_forwarded' from message =
where is_forwarded is TRUE;</div>

<div>insert into message2 select folder_id,msg,'is_deleted' from message wh=
ere is_deleted is TRUE;</div>

<div>insert into message2 select folder_id,msg,'is_draft' from message wher=
e is_draft is TRUE;</div>

<div>insert into message2 select folder_id,msg,'is_flagged' from message wh=
ere is_flagged is TRUE;</div>

<div>=C2=A0</div>

<div>select is_flag from message2 where folder_id=3D1 group by 1;</div>

<div>=E2=80=8B</div>

<div>work=3D# select is_flag from message2 where folder_id=3D1 group by 1;<=
/div>

<div>=C2=A0 is_flag</div>

<div>------------</div>

<div>=C2=A0is_seen</div>

<div>=C2=A0is_deleted</div>

<div>=C2=A0is_replied</div>

<div>(3 rows)</div>
</div>
</blockquote>

<div>=C2=A0</div>

<div>New messages are inserted into the message-table &quot;all the time&qu=
ot; and it seems quite expensive to keep this key-value table updated (whic=
h it must be, using triggers).</div>

<div>=C2=A0</div>

<div>My version returns in sub-millisecond for a folder with &gt; 100K mess=
ages in it, which I think is not bad, I just don't like the looks of the qu=
ery and all the indexes required.</div>

<div>=C2=A0</div>

<div>Thanks for looking into this.</div>

<div>=C2=A0</div>

<div class=3D"origo-email-signature">
<div>--
<div><span style=3D"font-family:arial,helvetica,sans-serif;"><strong>Andrea=
s Joseph Krogh</strong></span></div>

<div><span style=3D"font-family:arial,helvetica,sans-serif;">CTO / Partner<=
/span> - Visena AS</div>

<div><span style=3D"font-family:arial,helvetica,sans-serif;">Mobile: +47 90=
9 56 963</span></div>

<div><a href=3D"mailto:andreas@visena.com">andreas@visena.com</a></div>

<div><a href=3D"https://www.visena.com">www.visena.com</a></div>

<div style=3D"padding-top: 5px"><a href=3D"https://www.visena.com"><img alt=
=3D"" style=3D"max-width: 100%;" src=3D"cid:part_F7646466834422MMYZW"></a><=
/div>
</div>
</div>

<div>=C2=A0</div>
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