cx_Oracle modernize

Full "RETURNING" support is implemented for the cx_Oracle dialect, meaning
multiple RETURNING rows are now recived for DML statements that produce
more than one row for RETURNING.

cx_Oracle 7 is now the minimum version for cx_Oracle.

Getting Oracle to do multirow returning took about 5 minutes.  however,
getting Oracle's RETURNING system to integrate with ORM-enabled
insert, update, delete, is a big deal because that architecture wasn't
really working very robustly, including some recent changes in 1.4
for FromStatement were done in a hurry, so this patch also cleans up
the FromStatement situation and begins to establish it more concretely
as the base for all ReturnsRows / TextClause ORM scenarios.

Fixes: #6245
Change-Id: I2b4e6007affa51ce311d2d5baa3917f356ab961f

2 files changed, 6 insertions, 5 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py
index 9bfde4768..999452804 100644
--- a/lib/sqlalchemy/dialects/postgresql/base.py
+++ b/lib/sqlalchemy/dialects/postgresql/base.py
@@ -2401,10 +2401,11 @@ class PGCompiler(compiler.SQLCompiler):
 
         return tmp
 
-    def returning_clause(self, stmt, returning_cols):
-
+    def returning_clause(
+        self, stmt, returning_cols, *, populate_result_map, **kw
+    ):
         columns = [
-            self._label_returning_column(stmt, c)
+            self._label_returning_column(stmt, c, populate_result_map)
             for c in expression._select_iterables(returning_cols)
         ]
 
diff --git a/lib/sqlalchemy/dialects/postgresql/psycopg2.py b/lib/sqlalchemy/dialects/postgresql/psycopg2.py
index 391368c5f..07783ced7 100644
--- a/lib/sqlalchemy/dialects/postgresql/psycopg2.py
+++ b/lib/sqlalchemy/dialects/postgresql/psycopg2.py
@@ -478,7 +478,7 @@ class PGExecutionContext_psycopg2(_PGExecutionContext_common_psycopg):
         if (
             self._psycopg2_fetched_rows
             and self.compiled
-            and self.compiled.returning
+            and self.compiled.effective_returning
         ):
             # psycopg2 execute_values will provide for a real cursor where
             # cursor.description works correctly. however, it executes the
@@ -736,7 +736,7 @@ class PGDialect_psycopg2(_PGDialect_common_psycopg):
                 statement,
                 parameters,
                 template=executemany_values,
-                fetch=bool(context.compiled.returning),
+                fetch=bool(context.compiled.effective_returning),
                 **kwargs,
             )