- The SQL compiler now generates the mapping of expected columnspositional_targeting

such that they are matched to the received result set positionally,
rather than by name.  Originally, this was seen as a way to handle
cases where we had columns returned with difficult-to-predict names,
though in modern use that issue has been overcome by anonymous
labeling.   In this version, the approach basically reduces function
call count per-result by a few dozen calls, or more for larger
sets of result columns.  The approach still degrades into a modern
version of the old approach if textual elements modify the result
map, or if any discrepancy in size exists between
the compiled set of columns versus what was received, so there's no
issue for partially or fully textual compilation scenarios where these
lists might not line up.  fixes #918
- callcounts still need to be adjusted down for this so zoomark
tests won't pass at the moment

1 files changed, 9 insertions, 2 deletions

diff --git a/lib/sqlalchemy/engine/default.py b/lib/sqlalchemy/engine/default.py
index 17d2e2531..9d2bbfb15 100644
--- a/lib/sqlalchemy/engine/default.py
+++ b/lib/sqlalchemy/engine/default.py
@@ -461,9 +461,9 @@ class DefaultExecutionContext(interfaces.ExecutionContext):
     is_crud = False
     isddl = False
     executemany = False
-    result_map = None
     compiled = None
     statement = None
+    _result_columns = None
     _is_implicit_returning = False
     _is_explicit_returning = False
 
@@ -525,7 +525,7 @@ class DefaultExecutionContext(interfaces.ExecutionContext):
         # compiled clauseelement.  process bind params, process table defaults,
         # track collections used by ResultProxy to target and process results
 
-        self.result_map = compiled.result_map
+        self._result_columns = compiled._result_columns
 
         self.unicode_statement = util.text_type(compiled)
         if not dialect.supports_unicode_statements:
@@ -663,6 +663,13 @@ class DefaultExecutionContext(interfaces.ExecutionContext):
         self.cursor = self.create_cursor()
         return self
 
+    @property
+    def result_map(self):
+        if self._result_columns:
+            return self.compiled.result_map
+        else:
+            return None
+
     @util.memoized_property
     def engine(self):
         return self.root_connection.engine