perf improvements related to corresponding_column (2)

commit two of two. this reorganizes ColumnCollection
to build a new index up front that's used to optimize
the corresponding_column() method.

Additional performance enhancements within ORM-enabled SQL statements,
specifically targeting callcounts within the construction of ORM
statements, using combinations of :func:`_orm.aliased` with
:func:`_sql.union` and similar "compound" constructs, in addition to direct
performance improvements to the ``corresponding_column()`` internal method
that is used heavily by the ORM by constructs like :func:`_orm.aliased` and
similar.

Fixes: #8796
Change-Id: I4a76788007d5a802b9a4081e6a0f6e4b52497b50

1 files changed, 20 insertions, 3 deletions

diff --git a/test/base/test_utils.py b/test/base/test_utils.py
index 098652928..349ee8c05 100644
--- a/test/base/test_utils.py
+++ b/test/base/test_utils.py
@@ -567,15 +567,32 @@ class ToListTest(fixtures.TestBase):
 
 class ColumnCollectionCommon(testing.AssertsCompiledSQL):
     def _assert_collection_integrity(self, coll):
-        eq_(coll._colset, set(c for k, c in coll._collection))
+        eq_(coll._colset, set(c for k, c, _ in coll._collection))
         d = {}
-        for k, col in coll._collection:
+        for k, col, _ in coll._collection:
             d.setdefault(k, (k, col))
         d.update(
-            {idx: (k, col) for idx, (k, col) in enumerate(coll._collection)}
+            {idx: (k, col) for idx, (k, col, _) in enumerate(coll._collection)}
         )
         eq_(coll._index, d)
 
+        if not coll._proxy_index:
+            coll._init_proxy_index()
+
+        all_metrics = {
+            metrics for mm in coll._proxy_index.values() for metrics in mm
+        }
+        eq_(
+            all_metrics,
+            {m for (_, _, m) in coll._collection},
+        )
+
+        for mm in all_metrics:
+            for eps_col in mm.get_expanded_proxy_set():
+                assert mm in coll._proxy_index[eps_col]
+                for mm_ in coll._proxy_index[eps_col]:
+                    assert eps_col in mm_.get_expanded_proxy_set()
+
     def test_keys(self):
         c1, c2, c3 = sql.column("c1"), sql.column("c2"), sql.column("c3")
         c2.key = "foo"