Note: The following description applies both to Postgres-XC and PostgreSQL if not described explicitly.
DROP INDEX drops an existing index from the database system. To execute this command you must be the owner of the index.
Do not throw an error if the index does not exist. A notice is issued in this case.
The name (optionally schema-qualified) of an index to remove.
Automatically drop objects that depend on the index.
Refuse to drop the index if any objects depend on it. This is the default.