oracle can conditionally decide if it wants to say "use rowid" in a select statement.

needs to be tweaked vs. when ROW NUMBER OVER ORDER BY is being used, but currently
fixes [ticket:436]

2 files changed, 8 insertions, 3 deletions

diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py
index 77ab866c7..c7b5d93fe 100644
--- a/lib/sqlalchemy/engine/base.py
+++ b/lib/sqlalchemy/engine/base.py
@@ -52,8 +52,13 @@ class Dialect(sql.AbstractDialect):
         which comes from the types module.  Subclasses will usually use the adapt_type()
         method in the types module to make this job easy."""
         raise NotImplementedError()
-    def oid_column_name(self):
-        """returns the oid column name for this dialect, or None if the dialect cant/wont support OID/ROWID."""
+    def oid_column_name(self, column):
+        """return the oid column name for this dialect, or None if the dialect cant/wont support OID/ROWID.
+        
+        the Column instance which represents OID for the query being compiled is passed, so that the dialect
+        can inspect the column and its parent selectable to determine if OID/ROWID is not selected for a particular
+        selectable (i.e. oracle doesnt support ROWID for UNION, GROUP BY, DISTINCT, etc.)
+        """
         raise NotImplementedError()
     def supports_sane_rowcount(self):
         """Provided to indicate when MySQL is being used, which does not have standard behavior
diff --git a/lib/sqlalchemy/engine/default.py b/lib/sqlalchemy/engine/default.py
index 94c01f324..06409377c 100644
--- a/lib/sqlalchemy/engine/default.py
+++ b/lib/sqlalchemy/engine/default.py
@@ -41,7 +41,7 @@ class DefaultDialect(base.Dialect):
         if type(typeobj) is type:
             typeobj = typeobj()
         return typeobj
-    def oid_column_name(self):
+    def oid_column_name(self, column):
         return None
     def supports_sane_rowcount(self):
         return True