- :meth:`.MetaData.create_all` and :meth:`.MetaData.drop_all` will

now accommodate an empty list as an instruction to not create/drop
any items, rather than ignoring the collection. [ticket:2664].
This is a behavioral change and extra notes to the changelog
and migration document have been added.

- create a new test suite for exercising codepaths
in engine/ddl.py

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/sqlalchemy/engine/ddl.py b/lib/sqlalchemy/engine/ddl.py
index 6035e2901..c61a9d59c 100644
--- a/lib/sqlalchemy/engine/ddl.py
+++ b/lib/sqlalchemy/engine/ddl.py
@@ -21,7 +21,7 @@ class SchemaGenerator(DDLBase):
                  tables=None, **kwargs):
         super(SchemaGenerator, self).__init__(connection, **kwargs)
         self.checkfirst = checkfirst
-        self.tables = tables and set(tables) or None
+        self.tables = tables
         self.preparer = dialect.identifier_preparer
         self.dialect = dialect
         self.memo = {}
@@ -49,7 +49,7 @@ class SchemaGenerator(DDLBase):
             )
 
     def visit_metadata(self, metadata):
-        if self.tables:
+        if self.tables is not None:
             tables = self.tables
         else:
             tables = metadata.tables.values()
@@ -117,7 +117,7 @@ class SchemaDropper(DDLBase):
         self.memo = {}
 
     def visit_metadata(self, metadata):
-        if self.tables:
+        if self.tables is not None:
             tables = self.tables
         else:
             tables = metadata.tables.values()