Re: Inline count on a query

On Wednesday, 19 August 2020 15:09, David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com> wrote:

> On Wednesday, August 19, 2020, Laura Smith <n5d9xq3ti233xiyif2vp(at)protonmail(dot)ch> wrote:
>
> > 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 ?
>
> Suggest you provide your desired output in table format, and show “the query” that you mention.
>
> David J.

If I knew what "the query" was, I wouldn't be posting here.  ;-p

The only thing I've managed to come up with so far is adding count(*) over (partition by digest(lan_id||net_id,'sha256')) to my query, but that obviously gives the total count, not the ongoing incremental count.