From: | Laura Smith <n5d9xq3ti233xiyif2vp(at)protonmail(dot)ch> |
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To: | postgre <pgsql-general(at)lists(dot)postgresql(dot)org> |
Subject: | Inline count on a query |
Date: | 2020-08-19 13:38:51 |
Message-ID: | F3iOTSNGzv1T_JMTvrmpNewuHtkpyPEiCsjbylqO0bAE1ghq4UDmUi78s_0fMAPOkLuN9mzZQyQfzBKex68XqsO09BCNyQ9DmPySbd7_8F8=@protonmail.ch |
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Lists: | pgsql-general |
Hi,
Let's say we've got a fairly basic table :
create table networks (
lan_id text not null,
net_id text not null,
port_id text not null
);
create index net_uniq on networks(lan_id,port_id);
The query conundrum I am facing is that I need to add metadata to the output of the query that indicates the count of ports a given net has on a lan.
So, for example, given :
insert into networks(lan_id,net_id,port_id) values('L1','N1,'P1');
insert into networks(lan_id,net_id,port_id) values('L1','N1,'P2');
The metadata count would be 1, 2 (because 'N1' has 'P1' and 'P2' on 'L1').
Is there a sensible way to query this without stressing out Postgres too much ? I'm guessing a CTE of some sort ?
Laura
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