Use expanding IN for all literal value IN expressions

The "expanding IN" feature, which generates IN expressions at query
execution time which are based on the particular parameters associated with
the statement execution, is now used for all IN expressions made against
lists of literal values.   This allows IN expressions to be fully cacheable
independently of the list of values being passed, and also includes support
for empty lists. For any scenario where the IN expression contains
non-literal SQL expressions, the old behavior of pre-rendering for each
position in the IN is maintained. The change also completes support for
expanding IN with tuples, where previously type-specific bind processors
weren't taking effect.

As part of this change, a more explicit separation between
"literal execute" and "post compile" bound parameters is being made;
as the "ansi bind rules" feature is rendering bound parameters
inline, as we now support "postcompile" generically, these should
be used here, however we have to render literal values at
execution time even for "expanding" parameters.  new test fixtures
etc. are added to assert everything goes to the right place.

Fixes: #4645
Change-Id: Iaa2b7bfbfaaf5b80799ee17c9b8507293cba6ed1

1 files changed, 2 insertions, 18 deletions

diff --git a/examples/sharding/attribute_shard.py b/examples/sharding/attribute_shard.py
index 608f0f9c3..7b8f87d90 100644
--- a/examples/sharding/attribute_shard.py
+++ b/examples/sharding/attribute_shard.py
@@ -17,11 +17,8 @@ from sqlalchemy.sql import operators
 from sqlalchemy.sql import visitors
 
 
-# db1 is used for id generation. The "pool_threadlocal"
-# causes the id_generator() to use the same connection as that
-# of an ongoing transaction within db1.
 echo = True
-db1 = create_engine("sqlite://", echo=echo, pool_threadlocal=True)
+db1 = create_engine("sqlite://", echo=echo)
 db2 = create_engine("sqlite://", echo=echo)
 db3 = create_engine("sqlite://", echo=echo)
 db4 = create_engine("sqlite://", echo=echo)
@@ -220,20 +217,7 @@ def _get_query_comparisons(query):
         clauses.add(column)
 
     def visit_binary(binary):
-        # special handling for "col IN (params)"
-        if (
-            binary.left in clauses
-            and binary.operator == operators.in_op
-            and hasattr(binary.right, "clauses")
-        ):
-            comparisons.append(
-                (
-                    binary.left,
-                    binary.operator,
-                    tuple(binds[bind] for bind in binary.right.clauses),
-                )
-            )
-        elif binary.left in clauses and binary.right in binds:
+        if binary.left in clauses and binary.right in binds:
             comparisons.append(
                 (binary.left, binary.operator, binds[binary.right])
             )