UUID columns in Piccolo >= 1.31.0

Prior to piccolo==1.31.0, Postgres UUID columns generated their default values using uuid_generate_v4(), which is part of the uuid-ossp extension.

In all the versions of Posgres that Piccolo supports, there is now a gen_random_uuid() function built in, which Piccolo now uses for all new UUID columns for generating default values in the database.

Your existing UUID columns will be left alone, and will continue to use the uuid-ossp extension.

Note that PostgresEngine has an extensions argument. These are Postgres extensions which Piccolo will try to enable when starting up. This used to include uuid-ossp by default, but this is no longer the case. If you want to maintain the old behaviour, simply do this:

DB = PostgresEngine(extensions=['uuid-ossp'])

If you want to migrate an existing UUID column over to use gen_random_uuid() then run this script:

ALTER TABLE my_table ALTER COLUMN my_uuid_column SET DEFAULT gen_random_uuid();