Merge "Revert cx_Oracle WITH_UNICODE change under > 5.0"

1 files changed, 13 insertions, 4 deletions

diff --git a/lib/sqlalchemy/dialects/oracle/cx_oracle.py b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
index f6c3c97b7..4e9f6314b 100644
--- a/lib/sqlalchemy/dialects/oracle/cx_oracle.py
+++ b/lib/sqlalchemy/dialects/oracle/cx_oracle.py
@@ -723,19 +723,28 @@ class OracleDialect_cx_oracle(OracleDialect):
             self._cx_oracle_string_types = set()
             self._cx_oracle_with_unicode = False
         elif util.py3k or (
-                self.cx_oracle_ver >= (5,) and not \
+                self.cx_oracle_ver >= (5,) and
+                self.cx_oracle_ver < (5, 1) and not
                 hasattr(self.dbapi, 'UNICODE')
         ):
             # cx_Oracle WITH_UNICODE mode.  *only* python
-            # unicode objects accepted for anything
+            # unicode objects accepted for anything.  This
+            # mode of operation is implicit for Python 3,
+            # however under Python 2 it existed as a never-used build-time
+            # option for cx_Oracle 5.0 only and was removed in 5.1.
             self.supports_unicode_statements = True
             self.supports_unicode_binds = True
             self._cx_oracle_with_unicode = True
 
             if util.py2k:
                 # There's really no reason to run with WITH_UNICODE under
-                # Python 2.x.  However as of cx_oracle 5.3 it seems to be
-                # set to ON for default builds
+                # Python 2.x.  Give the user a hint.
+                util.warn(
+                    "cx_Oracle is compiled under Python 2.xx using the "
+                    "WITH_UNICODE flag.  Consider recompiling cx_Oracle "
+                    "without this flag, which is in no way necessary for "
+                    "full support of Unicode and causes significant "
+                    "performance issues.")
                 self.execution_ctx_cls = \
                     OracleExecutionContext_cx_oracle_with_unicode
         else: