Import in postgres json data in a csv file
The PostgreSQL COPY command is seldom ideal, but it often works. For reference there are better methods to figure this out than guessing.

CREATE TEMP TABLE baz AS
  SELECT 1::int, '{"a":"b"}'::jsonb;


This is your exact sample data. Now we can test different settings..

# COPY baz TO STDOUT;
1   {"a": "b"}

COPY baz TO STDOUT DELIMITER ',';
1,{"a": "b"}


You'll see that the above generates the exact data your questioning...

COPY baz TO '/tmp/data.csv' DELIMITER ',';


There is no problem. At least not with PostgreSQL 9.5.

CSV Mode

So where is your problem, it's with CSV-mode. Observe,

# COPY baz TO STDOUT;
1   {"a": "b"}
# COPY baz TO STDOUT CSV;
1,"{""a"": ""b""}"


You can see these two are different now. Let's try to load the non-CSV file in CSV mode which assumes the format that CSV mode generated above.

TRUNCATE baz;
COPY baz FROM '/tmp/data.csv' DELIMITER ',' CSV;
ERROR:  invalid input syntax for type json
DETAIL:  Token "a" is invalid.
CONTEXT:  JSON data, line 1: {a...
COPY baz, line 1, column jsonb: "{a: b}"


Now we error. The reason for that comes from RFC 4180


  Each field may or may not be enclosed in double quotes (however
         some programs, such as Microsoft Excel, do not use double quotes
         at all).  If fields are not enclosed with double quotes, then
         double quotes may not appear inside the fields.



So JSON RFC 4627 specifies an object's names in name/value pairs must be strings which require double quotes.
And CSV RFC 4180 specifies that if any double quotes are inside the field, then the whole field must be quoted.


At this point you have two options..


Don't use CSV mode.
Or, Escape the inner quotes.


So these would be valid inputs under the same options in CSV mode.

#COPY baz TO STDOUT DELIMITER ',' CSV ESCAPE E'\\';
1,"{\"a\": \"b\"}"

# COPY baz TO STDOUT DELIMITER ',' CSV;
1,"{""a"": ""b""}"