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:
{"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"}]}
Then, I try to get the same data in the other way:
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';
And the result I got is quite match what I expect.
{"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"}]}
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?