add a column cache to Relations

core/dbt/adapters/base/impl.py

@@ -441,8 +441,7 @@ def rename_relation(self, from_relation, to_relation):
  )
 
  @abc.abstractmethod
- @available
- def get_columns_in_relation(self, relation):
+ def _get_columns_in_relation(self, relation):
  """Get a list of the columns in the given Relation.
 
  :param self.Relation relation: The relation to query for.
@@ -453,6 +452,22 @@ def get_columns_in_relation(self, relation):
  '`get_columns_in_relation` is not implemented for this adapter!'
  )
 
+ @available
+ def get_columns_in_relation(self, relation):
+ """Get a list of the columns in the given Relation. Use the cache if it
+ is available.
+
+ :param self.Relation relation: The relation to query for.
+ :return: Information about all columns in the given relation.
+ :rtype: List[self.Column]
+ """
+ columns = relation.column_cache
+ if columns is None:
+ columns = self._get_columns_in_relation(relation)
+ if dbt.flags.USE_CACHE:
+ relation.column_cache = columns
+ return columns
+
  @available_deprecated('get_columns_in_relation')
  def get_columns_in_table(self, schema, identifier):
  """DEPRECATED: Get a list of the columns in the given table."""

core/dbt/adapters/base/relation.py

@@ -80,6 +80,10 @@ class BaseRelation(APIObject):
 
  PATH_ELEMENTS = ['database', 'schema', 'identifier']
 
+ def __init__(self, *args, **kwargs):
+ super(BaseRelation, self).__init__(*args, **kwargs)
+ self.column_cache = None
+
  def matches(self, database=None, schema=None, identifier=None):
  search = filter_null_values({
  'database': database,

core/dbt/adapters/sql/impl.py

@@ -111,6 +111,7 @@ def alter_column_type(self, relation, column_name, new_column_type):
  3. Drop the existing column (cascade!)
  4. Rename the new column to existing column
  """
+ relation.column_cache = None
  kwargs = {
  'relation': relation,
  'column_name': column_name,
@@ -150,7 +151,7 @@ def rename_relation(self, from_relation, to_relation):
  kwargs=kwargs
  )
 
- def get_columns_in_relation(self, relation):
+ def _get_columns_in_relation(self, relation):
  return self.execute_macro(
  GET_COLUMNS_IN_RELATION_MACRO_NAME,
  kwargs={'relation': relation}

plugins/bigquery/dbt/adapters/bigquery/impl.py

@@ -84,7 +84,7 @@ def list_schemas(self, database):
  include_all=True)
  return [ds.dataset_id for ds in all_datasets]
 
- def get_columns_in_relation(self, relation):
+ def _get_columns_in_relation(self, relation):
  try:
  table = self.connections.get_bq_table(
  database=relation.database,