Handle search space decode failures in _query_historical_experiments_given_parameters (#5147)

ax/storage/sqa_store/load.py

@@ -787,18 +787,22 @@ def _query_historical_experiments_given_parameters(
             experiments_params[exp_name].append(sqa_param)
             experiments_time_created[exp_name] = time_created
 
-        return {
-            exp_name: (
-                decoder.search_space_from_sqa(
+        results: dict[str, tuple[SearchSpace | None, datetime]] = {}
+        for exp_name, parameters_sqa in experiments_params.items():
+            try:
+                search_space = decoder.search_space_from_sqa(
                     parameters_sqa=parameters_sqa,
                     # Parameter constraints don't matter for search space
                     # compatibility
                     parameter_constraints_sqa=[],
-                ),
-                experiments_time_created[exp_name],
-            )
-            for exp_name, parameters_sqa in experiments_params.items()
-        }
+                )
+            except Exception as e:
+                logger.warning(
+                    f"Failed to decode search space for experiment '{exp_name}': {e}"
+                )
+                search_space = None
+            results[exp_name] = (search_space, experiments_time_created[exp_name])
+        return results
 
 
 def identify_transferable_experiments(

ax/storage/sqa_store/tests/test_sqa_store.py

@@ -3236,6 +3236,61 @@ def test_query_historical_experiments_given_parameters(self) -> None:
             self.assertIn("w", none_throws(returned_ss).parameters)
             self.assertIn("x", none_throws(returned_ss).parameters)
 
+        with self.subTest("returns_none_search_space_on_decode_failure"):
+            # Save two experiments
+            exp1 = get_experiment_with_batch_trial()
+            exp1.name = "exp_decode_success"
+            exp1.experiment_type = "TEST"
+            exp1.is_test = False
+            trial1 = exp1.trials[0]
+            exp1.attach_data(get_data(trial_index=trial1.index))
+            save_experiment(exp1, config=config)
+
+            exp2 = get_experiment_with_batch_trial()
+            exp2.name = "exp_decode_failure"
+            exp2.experiment_type = "TEST"
+            exp2.is_test = False
+            trial2 = exp2.trials[0]
+            exp2.attach_data(get_data(trial_index=trial2.index))
+            save_experiment(exp2, config=config)
+
+            # Look up exp2's ID before mocking to avoid nested session_scope
+            with session_scope() as session:
+                exp2_id: int = (
+                    session.query(SQAExperiment.id)
+                    .filter(SQAExperiment.name == "exp_decode_failure")
+                    .scalar()
+                )
+
+            # Mock decoder to raise on the second experiment's parameters
+            original_search_space_from_sqa: Callable[..., SearchSpace | None] = (
+                Decoder.search_space_from_sqa
+            )
+
+            def _side_effect(self: Decoder, **kwargs: Any) -> SearchSpace | None:
+                params = kwargs.get("parameters_sqa", [])
+                exp_ids = {p.experiment_id for p in params}
+                if exp_ids == {exp2_id}:
+                    raise RuntimeError("Simulated decode failure")
+                return original_search_space_from_sqa(self, **kwargs)
+
+            with patch.object(Decoder, "search_space_from_sqa", _side_effect):
+                result = _query_historical_experiments_given_parameters(
+                    parameter_names=["w", "x"],
+                    experiment_types=["TEST"],
+                    config=config,
+                )
+
+            # The successfully decoded experiment should have a SearchSpace
+            self.assertIn("exp_decode_success", result)
+            ss_success, _ = result["exp_decode_success"]
+            self.assertIsNotNone(ss_success)
+
+            # The failed experiment should have None search space
+            self.assertIn("exp_decode_failure", result)
+            ss_failure, _ = result["exp_decode_failure"]
+            self.assertIsNone(ss_failure)
+
     def test_identify_transferable_experiments(
         self,
     ) -> None: