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]

6 files changed, 16 insertions, 8 deletions

diff --git a/lib/sqlalchemy/ansisql.py b/lib/sqlalchemy/ansisql.py
index 69b082e41..803cba6d3 100644
--- a/lib/sqlalchemy/ansisql.py
+++ b/lib/sqlalchemy/ansisql.py
@@ -215,7 +215,7 @@ class ANSICompiler(sql.Compiled):
             self.strings[column] = self.preparer.format_column(column)
         else:
             if column.table.oid_column is column:
-                n = self.dialect.oid_column_name()
+                n = self.dialect.oid_column_name(column)
                 if n is not None:
                     self.strings[column] = "%s.%s" % (self.preparer.format_table(column.table, use_schema=False), n)
                 elif len(column.table.primary_key) != 0:
diff --git a/lib/sqlalchemy/databases/oracle.py b/lib/sqlalchemy/databases/oracle.py
index 6008ae61c..b5bd72e8f 100644
--- a/lib/sqlalchemy/databases/oracle.py
+++ b/lib/sqlalchemy/databases/oracle.py
@@ -192,8 +192,11 @@ class OracleDialect(ansisql.ANSIDialect):
     def type_descriptor(self, typeobj):
         return sqltypes.adapt_type(typeobj, colspecs)
 
-    def oid_column_name(self):
-        return "rowid"
+    def oid_column_name(self, column):
+        if not isinstance(column.table, sql.TableClause) and not isinstance(column.table, sql.Select):
+            return None
+        else:
+            return "rowid"
 
     def create_execution_context(self):
         return OracleExecutionContext(self)
diff --git a/lib/sqlalchemy/databases/postgres.py b/lib/sqlalchemy/databases/postgres.py
index e3ac3ae2c..7eee35320 100644
--- a/lib/sqlalchemy/databases/postgres.py
+++ b/lib/sqlalchemy/databases/postgres.py
@@ -279,7 +279,7 @@ class PGDialect(ansisql.ANSIDialect):
         else:
             return self.context.last_inserted_ids
 
-    def oid_column_name(self):
+    def oid_column_name(self, column):
         if self.use_oids:
             return "oid"
         else:
diff --git a/lib/sqlalchemy/databases/sqlite.py b/lib/sqlalchemy/databases/sqlite.py
index 6d1e56a7c..dda488f9c 100644
--- a/lib/sqlalchemy/databases/sqlite.py
+++ b/lib/sqlalchemy/databases/sqlite.py
@@ -165,7 +165,7 @@ class SQLiteDialect(ansisql.ANSIDialect):
     def last_inserted_ids(self):
         return self.context.last_inserted_ids
     
-    def oid_column_name(self):
+    def oid_column_name(self, column):
         return "oid"
 
     def dbapi(self):
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