Support `DEFAULT` value / auto-`UUID` column in `CREATE` (similar to `SERIAL`)

[prrao87]

Discussed in https://github.com/kuzudb/kuzu/discussions/3125

^{Originally posted by sapalli2989 March 23, 2024} It would be great, if we could declare within CREATE/DDL, that ids of a UUID column are to be auto-created via gen_random_uuid(). This feature would be analogue to SERIAL for integer sequences.

Currently Kuzu provides gen_random_uuid() for UUIDv4 auto-creation. But the need to invoke this function manually for new nodes with UUID primary key is inconvenient and sometimes not easily possible - as seen with MERGE in https://github.com/kuzudb/kuzu/issues/3014. Actually I think proposal here is more useful than linked one.

PostgreSQL provides DEFAULT value keyword within CREATE in combination with equally named gen_random_uuid() for these cases (more examples in 1, 2):

CREATE TABLE table_name (
    unique_id UUID DEFAULT gen_random_uuid(),
    ...
    PRIMARY KEY (unique_id)
);

or with directly prepended PRIMARY KEY:

CREATE TABLE table_name (
    unique_id UUID DEFAULT gen_random_uuid() PRIMARY KEY,
    ...
);

, requested for Kuzu in https://github.com/kuzudb/kuzu/issues/2911.

I think this would be a nice addition to usability of UUIDs.