Support cross-database column lookups

Fixes: #679

dbt/adapters/bigquery.py

@@ -379,7 +379,10 @@ def get_existing_schemas(cls, profile, model_name=None):
 
     @classmethod
     def get_columns_in_table(cls, profile, schema_name, table_name,
-                             model_name=None):
+                             database=None, model_name=None):
+
+        # BigQuery does not have databases -- the database parameter is here
+        # for consistency with the base implementation
 
         conn = cls.get_connection(profile, model_name)
         client = conn.get('handle')

dbt/adapters/default.py

@@ -192,32 +192,36 @@ def get_missing_columns(cls, profile,
                 if col_name in missing_columns]
 
     @classmethod
-    def _get_columns_in_table_sql(cls, schema_name, table_name):
+    def _get_columns_in_table_sql(cls, schema_name, table_name, database):
 
         schema_filter = '1=1'
         if schema_name is not None:
             schema_filter = "table_schema = '{}'".format(schema_name)
 
+        db_prefix = '' if database is None else '{}.'format(database)
+
         sql = """
         select
             column_name,
             data_type,
             character_maximum_length,
             numeric_precision || ',' || numeric_scale as numeric_size
 
-        from information_schema.columns
+        from {db_prefix}information_schema.columns
         where table_name = '{table_name}'
           and {schema_filter}
         order by ordinal_position
-        """.format(table_name=table_name, schema_filter=schema_filter).strip()
+        """.format(db_prefix=db_prefix,
+                   table_name=table_name,
+                   schema_filter=schema_filter).strip()
 
         return sql
 
     @classmethod
     def get_columns_in_table(cls, profile, schema_name, table_name,
-                             model_name=None):
+                             database=None, model_name=None):
 
-        sql = cls._get_columns_in_table_sql(schema_name, table_name)
+        sql = cls._get_columns_in_table_sql(schema_name, table_name, database)
         connection, cursor = cls.add_query(
             profile, sql, model_name)
 

dbt/adapters/redshift.py

@@ -18,7 +18,10 @@ def date_function(cls):
         return 'getdate()'
 
     @classmethod
-    def _get_columns_in_table_sql(cls, schema_name, table_name):
+    def _get_columns_in_table_sql(cls, schema_name, table_name, database):
+        # Redshift doesn't support cross-database queries,
+        # so we can ignore the `database` argument
+
         # TODO : how do we make this a macro?
         if schema_name is None:
             table_schema_filter = '1=1'