Re: Conflict between JSON_AGG and COPY

On 04/08/2018 08:44 PM, Đỗ Ngọc Trí Cường wrote:
> Dear Arian Klaver,
>
> I think there is a misunderstood here.
>
> I think that I quite understand how is the second query run.
>
> The question I asked here is why exporting data, which is generated by a
> query "JSON_AGG" , with command "COPY". The data contain "\n" as 2
> characters instead of "new line" character.
>
> The second query is for the old version of PostgreSQL (9.3 and previous)
> cause of they don't have JSON_AGG aggregate function. Since 9.4, we have
> "JSON_AGG" already. So I want to rewrite and reduce the length of the
> query. But it is don't work as I expected with command COPY.

COPY
(select json_build_object('RECORDS', ARRAY_AGG(t) ) from test_table t)
TO '/home/postgres/test2.json';

cat test2.json

{"RECORDS" :
[{"id":1,"username":"john","fullname":"John"},{"id":2,"username":"anna","fullname":"Anna"},{"id":3,"username":"sussi","fullname":"Sussi"},{"id":4,"username":"david","fullname":"David
Beckham"},{"id":5,"username":"wayne","fullname":"Wayne Rooney"}]}

>
> Thank you and best regards,
>
>
> Đỗ Ngọc Trí*Cường*(Mr.) | *Software Development Department*| +84 28 3715
> 5325

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com