Conflict between JSON_AGG and COPY

Dear all,

I've found one case. I don't know this is a bug or I config/query some things wrong.

Let I describe it. I have a table with structure and data is:

id | username | fullname
----+-------------+---------------
1 | john | John
2 | anna | Anna
3 | sussi | Sussi
4 | david | David Beckham
5 | wayne | Wayne Rooney

I want to export it to a file in JSON format so I run the query as below:

COPY (SELECT row_to_json(t) FROM (SELECT json_agg(t1) AS "RECORDS" FROM test_table t1) t) TO '/home/postgres/test1.json';

But the result I got will include "\n" in the result:

BQ_BEGIN

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

BQ_END

Then, I try to get the same data in the other way:

BQ_BEGIN

COPY (WITH t2 AS (select row_to_json(t) as js from test_table t),
t1 AS (SELECT ARRAY_TO_JSON(array_agg(js)) as "RECORDS" FROM t2)
SELECT row_to_json(t1) FROM t1)
TO '/home/postgres/test2.json';

BQ_END

And the result I got is quite match what I expect.

BQ_BEGIN

{"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"}]}

BQ_END

I think the COPY command does not the `\n` character for pretty in `json_agg` command.

Please help me give me your idea. Am I wrong or this is really a bug?

Thank you and best regards,

Đỗ Ngọc Trí Cường (Mr.)

Software Development Dept.

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