PostgreSQL: INSERT ... ON CONFLICT DO NOTHING raises DbError

[moigagoo]

I'm implementing a way to ignore conflicts during insertion in Norm: moigagoo/norm#120

I've stumbled upon an issue with Postgres in ndb.

If you have an INSERT query with ON CONFLICT DO NOTHING, the query fails despite being a totally valid query with a totally normal result.

I think the root of the problem lays here: https://github.com/xzfc/ndb.nim/blob/master/ndb/postgres.nim#L705

I'm not sure what pqNfields(res), pqntuples(res), or pqgetisnull(res, 0, 0) are but it seems like this check validates that a row was created in the db and raises an error if it wasn't. However, the row shouldn't be created, this is explicitly requested with ON CONFLICT DO NOTHING clause.

In the case of ON CONFLICT DO NOTHING the values are:

• pqNfields(res) == 1
• pqntuples(res) == 0
• pqgetisnull(res, 0, 0) == 1