On 12/6/23 14:47, Joe Conway wrote:
On 12/6/23 13:59, Daniel Verite wrote:
Andrew Dunstan wrote:
IMNSHO, we should produce either a single JSON
document (the ARRAY case) or a series of JSON documents, one per row
(the LINES case).
"COPY Operations" in the doc says:
" The backend sends a CopyOutResponse message to the frontend, followed
by zero or more CopyData messages (always one per row), followed by
CopyDone".
In the ARRAY case, the first messages with the copyjsontest
regression test look like this (tshark output):
PostgreSQL
Type: CopyOut response
Length: 13
Format: Text (0)
Columns: 3
Format: Text (0)
PostgreSQL
Type: Copy data
Length: 6
Copy data: 5b0a
PostgreSQL
Type: Copy data
Length: 76
Copy data:
207b226964223a312c226631223a226c696e652077697468205c2220696e2069743a2031…
The first Copy data message with contents "5b0a" does not qualify
as a row of data with 3 columns as advertised in the CopyOut
message. Isn't that a problem?
Is it a real problem, or just a bit of documentation change that I missed?
Anything receiving this and looking for a json array should know how to
assemble the data correctly despite the extra CopyData messages.
Hmm, maybe the real problem here is that Columns do not equal "3" for
the json mode case -- that should really say "1" I think, because the
row is not represented as 3 columns but rather 1 json object.
Does that sound correct?
Assuming yes, there is still maybe an issue that there are two more
"rows" that actual output rows (the "[" and the "]"), but maybe those
are less likely to cause some hazard?
--
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
