- make these failure cases more specific to catch Oracle.

Would be nice to fix Oracle here

4 files changed, 43 insertions, 9 deletions

diff --git a/doc/build/changelog/migration_11.rst b/doc/build/changelog/migration_11.rst
index 6ce0d031c..727b82015 100644
--- a/doc/build/changelog/migration_11.rst
+++ b/doc/build/changelog/migration_11.rst
@@ -96,13 +96,15 @@ SQLAlchemy Core looks like::
 Previously, the above construct would not produce parenthesization for the
 inner SELECT statements, producing a query that fails on all backends.
 
-The above formats will **continue to fail on SQLite**.
+The above formats will **continue to fail on SQLite**; additionally, the format
+that includes ORDER BY but no LIMIT/SELECT will **continue to fail on Oracle**.
 This is not a backwards-incompatible change, because the queries fail without
 the parentheses as well; with the fix, the queries at least work on all other
 databases.
 
 In all cases, in order to produce a UNION of limited SELECT statements that
-also works on SQLite, the subqueries must be a SELECT of an ALIAS::
+also works on SQLite and in all cases on Oracle, the
+subqueries must be a SELECT of an ALIAS::
 
     stmt1 = select([table1.c.x]).order_by(table1.c.y).limit(1).alias().select()
     stmt2 = select([table2.c.x]).order_by(table2.c.y).limit(2).alias().select()
diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
index 8b02f3e40..15bfad831 100644
--- a/lib/sqlalchemy/testing/requirements.py
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -111,8 +111,9 @@ class SuiteRequirements(Requirements):
         return exclusions.open()
 
     @property
-    def parens_in_union_contained_select(self):
-        """Target database must support parenthesized SELECT in UNION.
+    def parens_in_union_contained_select_w_limit_offset(self):
+        """Target database must support parenthesized SELECT in UNION
+        when LIMIT/OFFSET is specifically present.
 
         E.g. (SELECT ...) UNION (SELECT ..)
 
@@ -122,6 +123,20 @@ class SuiteRequirements(Requirements):
         return exclusions.open()
 
     @property
+    def parens_in_union_contained_select_wo_limit_offset(self):
+        """Target database must support parenthesized SELECT in UNION
+        when OFFSET/LIMIT is specifically not present.
+
+        E.g. (SELECT ... LIMIT ..) UNION (SELECT .. OFFSET ..)
+
+        This is known to fail on SQLite.  It also fails on Oracle
+        because without LIMIT/OFFSET, there is currently no step that
+        creates an additional subquery.
+
+        """
+        return exclusions.open()
+
+    @property
     def boolean_col_expressions(self):
         """Target database must support boolean expressions as columns"""
 
diff --git a/lib/sqlalchemy/testing/suite/test_select.py b/lib/sqlalchemy/testing/suite/test_select.py
index 0bcd35fd2..e7de356b8 100644
--- a/lib/sqlalchemy/testing/suite/test_select.py
+++ b/lib/sqlalchemy/testing/suite/test_select.py
@@ -242,7 +242,7 @@ class CompoundSelectTest(fixtures.TablesTest):
             [(2, 2, 3), (3, 3, 4)]
         )
 
-    @testing.requires.parens_in_union_contained_select
+    @testing.requires.parens_in_union_contained_select_w_limit_offset
     def test_limit_offset_selectable_in_unions(self):
         table = self.tables.some_table
         s1 = select([table]).where(table.c.id == 2).\
@@ -256,7 +256,7 @@ class CompoundSelectTest(fixtures.TablesTest):
             [(2, 2, 3), (3, 3, 4)]
         )
 
-    @testing.requires.parens_in_union_contained_select
+    @testing.requires.parens_in_union_contained_select_wo_limit_offset
     def test_order_by_selectable_in_unions(self):
         table = self.tables.some_table
         s1 = select([table]).where(table.c.id == 2).\
@@ -283,7 +283,7 @@ class CompoundSelectTest(fixtures.TablesTest):
             [(2, 2, 3), (3, 3, 4)]
         )
 
-    @testing.requires.parens_in_union_contained_select
+    @testing.requires.parens_in_union_contained_select_w_limit_offset
     def test_limit_offset_in_unions_from_alias(self):
         table = self.tables.some_table
         s1 = select([table]).where(table.c.id == 2).\
diff --git a/test/requirements.py b/test/requirements.py
index 939af4db1..fc8a3afd9 100644
--- a/test/requirements.py
+++ b/test/requirements.py
@@ -362,15 +362,32 @@ class DefaultRequirements(SuiteRequirements):
             ], 'no support for EXCEPT')
 
     @property
-    def parens_in_union_contained_select(self):
-        """Target database must support parenthesized SELECT in UNION.
+    def parens_in_union_contained_select_w_limit_offset(self):
+        """Target database must support parenthesized SELECT in UNION
+        when LIMIT/OFFSET is specifically present.
 
         E.g. (SELECT ...) UNION (SELECT ..)
 
+        This is known to fail on SQLite.
+
         """
         return fails_if('sqlite')
 
     @property
+    def parens_in_union_contained_select_wo_limit_offset(self):
+        """Target database must support parenthesized SELECT in UNION
+        when OFFSET/LIMIT is specifically not present.
+
+        E.g. (SELECT ... LIMIT ..) UNION (SELECT .. OFFSET ..)
+
+        This is known to fail on SQLite.  It also fails on Oracle
+        because without LIMIT/OFFSET, there is currently no step that
+        creates an additional subquery.
+
+        """
+        return fails_if('sqlite', 'oracle')
+
+    @property
     def offset(self):
         """Target database must support some method of adding OFFSET or
         equivalent to a result set."""