- attach the ResultMetaData to the Compiled object, when we detect that

the compiled cache is used.  That allows us to cache the whole metadata
and save on creating it at result time, when compiled cache is used.

2 files changed, 14 insertions, 4 deletions

diff --git a/lib/sqlalchemy/engine/result.py b/lib/sqlalchemy/engine/result.py
index 6c98dae18..0838d810d 100644
--- a/lib/sqlalchemy/engine/result.py
+++ b/lib/sqlalchemy/engine/result.py
@@ -269,9 +269,6 @@ class ResultMetaData(object):
         # high precedence keymap.
         keymap.update(primary_keymap)
 
-        if parent._echo:
-            context.engine.logger.debug(
-                "Col %r", tuple(x[0] for x in metadata))
 
     @util.pending_deprecation("0.8", "sqlite dialect uses "
                     "_translate_colname() now")
@@ -406,7 +403,18 @@ class ResultProxy(object):
     def _init_metadata(self):
         metadata = self._cursor_description()
         if metadata is not None:
-            self._metadata = ResultMetaData(self, metadata)
+            if self.context.compiled and \
+                    'compiled_cache' in self.context.execution_options:
+                if self.context.compiled._cached_metadata:
+                    self._metadata = self.context.compiled._cached_metadata
+                else:
+                    self._metadata = self.context.compiled._cached_metadata = \
+                        ResultMetaData(self, metadata)
+            else:
+                self._metadata = ResultMetaData(self, metadata)
+            if self._echo:
+                    self.context.engine.logger.debug(
+                    "Col %r", tuple(x[0] for x in metadata))
 
     def keys(self):
         """Return the current set of string keys for rows."""
diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 11608ef3b..010df5a16 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -170,6 +170,8 @@ class Compiled(object):
     defaults.
     """
 
+    _cached_metadata = None
+
     def __init__(self, dialect, statement, bind=None,
                 compile_kwargs=util.immutabledict()):
         """Construct a new ``Compiled`` object.