On 12/6/23 16:42, Sehrope Sarkuni wrote:
On Wed, Dec 6, 2023 at 4:29 PM Joe Conway <m...@joeconway.com
<mailto:m...@joeconway.com>> wrote:
> 1. Outputting a top level JSON object without the additional column
> keys. IIUC, the top level keys are always the column names. A
common use
> case would be a single json/jsonb column that is already formatted
> exactly as the user would like for output. Rather than enveloping
it in
> an object with a dedicated key, it would be nice to be able to
output it
> directly. This would allow non-object results to be outputted as
well
> (e.g., lines of JSON arrays, numbers, or strings). Due to how
JSON is
> structured, I think this would play nice with the JSON lines v.s.
array
> concept.
>
> COPY (SELECT json_build_object('foo', x) AS i_am_ignored FROM
> generate_series(1, 3) x) TO STDOUT WITH (FORMAT JSON,
> SOME_OPTION_TO_NOT_ENVELOPE)
> {"foo":1}
> {"foo":2}
> {"foo":3}
Your example does not match what you describe, or do I misunderstand? I
thought your goal was to eliminate the repeated "foo" from each row...
The "foo" in this case is explicit as I'm adding it when building the
object. What I was trying to show was not adding an additional object
wrapper / envelope.
So each row is:
{"foo":1}
Rather than:
"{"json_build_object":{"foo":1}}
I am still getting confused ;-)
Let's focus on the current proposed patch with a "minimum required
feature set".
Right now the default behavior is "JSON lines":
8<-------------------------------
COPY (SELECT x.i, 'val' || x.i as v FROM
generate_series(1, 3) x(i))
TO STDOUT WITH (FORMAT JSON);
{"i":1,"v":"val1"}
{"i":2,"v":"val2"}
{"i":3,"v":"val3"}
8<-------------------------------
and the other, non-default option is "JSON array":
8<-------------------------------
COPY (SELECT x.i, 'val' || x.i as v FROM
generate_series(1, 3) x(i))
TO STDOUT WITH (FORMAT JSON, FORCE_ARRAY);
[
{"i":1,"v":"val1"}
,{"i":2,"v":"val2"}
,{"i":3,"v":"val3"}
]
8<-------------------------------
So the questions are:
1. Do those two formats work for the initial implementation?
2. Is the default correct or should it be switched
e.g. rather than specifying FORCE_ARRAY to get an
array, something like FORCE_NO_ARRAY to get JSON lines
and the JSON array is default?
--
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
