Turn on caching everywhere, add logging

A variety of caching issues found by running
all tests with statement caching turned on.

The cache system now has a more conservative approach where
any subclass of a SQL element will by default invalidate
the cache key unless it adds the flag inherit_cache=True
at the class level, or if it implements its own caching.

Add working caching to a few elements that were
omitted previously; fix some caching implementations
to suit lesser used edge cases such as json casts
and array slices.

Refine the way BaseCursorResult and CursorMetaData
interact with caching; to suit cases like Alembic
modifying table structures, don't cache the
cursor metadata if it were created against a
cursor.description using non-positional matching,
e.g. "select *".   if a table re-ordered its columns
or added/removed, now that data is obsolete.

Additionally we have to adapt the cursor metadata
_keymap regardless of if we just processed
cursor.description, because if we ran against
a cached SQLCompiler we won't have the right
columns in _keymap.

Other refinements to how and when we do this
adaption as some weird cases
were exposed in the Postgresql dialect,
a text() construct that names just one column that
is not actually in the statement.   Fixed that
also as it looks like a cut-and-paste artifact
that doesn't actually affect anything.

Various issues with re-use of compiled result maps
and cursor metadata in conjunction with tables being
changed, such as change in order of columns.

mappers can be cleared but the class remains, meaning
a mapper has to use itself as the cache key not the class.

lots of bound parameter / literal issues, due to Alembic
creating a straight subclass of bindparam that renders
inline directly.   While we can update Alembic to not
do this, we have to assume other people might be doing
this, so bindparam() implements the inherit_cache=True
logic as well that was a bit involved.

turn on cache stats in logging.

Includes a fix to subqueryloader which moves all setup to
the create_row_processor() phase and elminates any storage
within the compiled context.   This includes some changes
to create_row_processor() signature and a revising of the
technique used to determine if the loader can participate
in polymorphic queries, which is also applied to
selectinloading.

DML update.values() and ordered_values() now coerces the
keys as we have tests that pass an arbitrary class here
which only includes __clause_element__(), so the
key can't be cached unless it is coerced.  this in turn
changed how composite attributes support bulk update
to use the standard approach of ClauseElement with
annotations that are parsed in the ORM context.

memory profiling successfully caught that the Session
from Query was getting passed into _statement_20()
so that was a big win for that test suite.

Apparently Compiler had .execute() and .scalar() methods
stuck on it, these date back to version 0.4 and there
was a single test in the PostgreSQL dialect tests
that exercised it for no apparent reason.   Removed
these methods as well as the concept of a Compiler
holding onto a "bind".

Fixes: #5386

Change-Id: I990b43aab96b42665af1b2187ad6020bee778784

1 files changed, 29 insertions, 25 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 2519438d1..61178291a 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -373,6 +373,8 @@ class Compiled(object):
 
     _cached_metadata = None
 
+    _result_columns = None
+
     schema_translate_map = None
 
     execution_options = util.immutabledict()
@@ -433,7 +435,6 @@ class Compiled(object):
         self,
         dialect,
         statement,
-        bind=None,
         schema_translate_map=None,
         render_schema_translate=False,
         compile_kwargs=util.immutabledict(),
@@ -463,7 +464,6 @@ class Compiled(object):
         """
 
         self.dialect = dialect
-        self.bind = bind
         self.preparer = self.dialect.identifier_preparer
         if schema_translate_map:
             self.schema_translate_map = schema_translate_map
@@ -527,24 +527,6 @@ class Compiled(object):
         """Return the bind params for this compiled object."""
         return self.construct_params()
 
-    def execute(self, *multiparams, **params):
-        """Execute this compiled object."""
-
-        e = self.bind
-        if e is None:
-            raise exc.UnboundExecutionError(
-                "This Compiled object is not bound to any Engine "
-                "or Connection.",
-                code="2afi",
-            )
-        return e._execute_compiled(self, multiparams, params)
-
-    def scalar(self, *multiparams, **params):
-        """Execute this compiled object and return the result's
-        scalar value."""
-
-        return self.execute(*multiparams, **params).scalar()
-
 
 class TypeCompiler(util.with_metaclass(util.EnsureKWArgType, object)):
     """Produces DDL specification for TypeEngine objects."""
@@ -687,6 +669,13 @@ class SQLCompiler(Compiled):
 
     insert_prefetch = update_prefetch = ()
 
+    _cache_key_bind_match = None
+    """a mapping that will relate the BindParameter object we compile
+    to those that are part of the extracted collection of parameters
+    in the cache key, if we were given a cache key.
+
+    """
+
     def __init__(
         self,
         dialect,
@@ -717,6 +706,9 @@ class SQLCompiler(Compiled):
 
         self.cache_key = cache_key
 
+        if cache_key:
+            self._cache_key_bind_match = {b: b for b in cache_key[1]}
+
         # compile INSERT/UPDATE defaults/sequences inlined (no pre-
         # execute)
         self.inline = inline or getattr(statement, "_inline", False)
@@ -875,8 +867,9 @@ class SQLCompiler(Compiled):
                     replace_context=err,
                 )
 
+            ckbm = self._cache_key_bind_match
             resolved_extracted = {
-                b.key: extracted
+                ckbm[b]: extracted
                 for b, extracted in zip(orig_extracted, extracted_parameters)
             }
         else:
@@ -907,7 +900,7 @@ class SQLCompiler(Compiled):
                 else:
                     if resolved_extracted:
                         value_param = resolved_extracted.get(
-                            bindparam.key, bindparam
+                            bindparam, bindparam
                         )
                     else:
                         value_param = bindparam
@@ -936,9 +929,7 @@ class SQLCompiler(Compiled):
                         )
 
                 if resolved_extracted:
-                    value_param = resolved_extracted.get(
-                        bindparam.key, bindparam
-                    )
+                    value_param = resolved_extracted.get(bindparam, bindparam)
                 else:
                     value_param = bindparam
 
@@ -2021,6 +2012,19 @@ class SQLCompiler(Compiled):
                     )
 
         self.binds[bindparam.key] = self.binds[name] = bindparam
+
+        # if we are given a cache key that we're going to match against,
+        # relate the bindparam here to one that is most likely present
+        # in the "extracted params" portion of the cache key.  this is used
+        # to set up a positional mapping that is used to determine the
+        # correct parameters for a subsequent use of this compiled with
+        # a different set of parameter values.   here, we accommodate for
+        # parameters that may have been cloned both before and after the cache
+        # key was been generated.
+        ckbm = self._cache_key_bind_match
+        if ckbm:
+            ckbm.update({bp: bindparam for bp in bindparam._cloned_set})
+
         if bindparam.isoutparam:
             self.has_out_parameters = True