Re: Extracting data from jsonb array?

Ken Tanzer <ken(dot)tanzer(at)gmail(dot)com> writes:
>> => select f.id, f.f1,f.f2,array_agg(t.key2) from foo as f,
>> jsonb_to_recordset(js) as t(key2 text) group by f.id;

> After a little more thought and experimenting, I'm not so sure about this
> part. In particular, I'm not clear why Postgres isn't complaining about
> the f1 and f2 fields. (It's not giving the "must appear in the GROUP BY
> clause or be used in an aggregate function" error that I would expect, and
> that I am getting when I try to apply this to my real query.)

> Can anyone explain to me why those fields don't need to be grouped? Thanks.

If foo.id is a primary key, it knows that the "group by" doesn't really
merge any rows of foo, so it lets you get away with that. I think this
is actually required by spec, but am too lazy to go check right now.

If foo.id isn't a primary key, then I'm confused too. Can we see the
full declaration of the table?

regards, tom lane