Re: Emitting JSON to file using COPY TO

On Wed, Feb 4, 2026 at 12:41 AM Florents Tselai
<florents(dot)tselai(at)gmail(dot)com> wrote:
>
> I (and others I assume) would really like to see this in 19;
> glancing at the thread above and in the test cases I see this is in good shape for comitter review.
> No?
>
> If I were to add something it would be an example in copy.sgml
> <para>
> When the <literal>FORCE_ARRAY</literal> option is enabled,
> the entire output is wrapped in a JSON array and individual rows are separated by commas:
> <programlisting>
> COPY (SELECT id, name FROM users) TO STDOUT (FORMAT JSON, FORCE_ARRAY);
> </programlisting>
> <programlisting>
> [
> {"id": 1, "name": "Alice"}
> ,{"id": 2, "name": "Bob"}
> ,{"id": 3, "name": "Charlie"}
> ]
> </programlisting>
> </para>
>

v23-0003-Add-option-force_array-for-COPY-JSON-FORMAT.patch
I've added:

+<para>
+ When the <literal>FORCE_ARRAY</literal> option is enabled,
+ the entire output is wrapped in a single JSON array with rows
separated by commas:
+<programlisting>
+COPY (SELECT * FROM (VALUES(1),(2)) val(id)) TO STDOUT (FORMAT JSON,
FORCE_ARRAY);
+</programlisting>
+The output is as follows:
+<screen>
+[
+ {"id":1}
+,{"id":2}
+]
+</screen>
+</para>
+
+

> Also, apologies if that has been discussed already,
> is there a good reason why didn't we just go with a simple "WRAP_ARRAY" ?
>

I don’t have a particular preference.
If the consensus is that WRAP_ARRAY is better than FORCE_ARRAY, we can
change it accordingly.

--
jian
https://www.enterprisedb.com/