On Wed, Dec 6, 2023, at 3:59 PM, Daniel Verite wrote: > 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? > > At least the json non-ARRAY case ("json lines") doesn't have > this issue, since every CopyData message corresponds effectively > to a row in the table.
Moreover, if your interface wants to process the COPY data stream while receiving it, you cannot provide "json array" format because each row (plus all of the received ones) is not a valid JSON. Hence, a JSON parser cannot be executed until you receive the whole data set. (wal2json format 1 has this disadvantage. Format 2 was born to provide a better alternative -- each row is a valid JSON.) I'm not saying that "json array" is not useful but that for large data sets, it is less useful. -- Euler Taveira EDB https://www.enterprisedb.com/