diff --git a/data/tpch_loader.py b/data/tpch_loader.py
index 97c2522a..8d04198a 100644
--- a/data/tpch_loader.py
+++ b/data/tpch_loader.py
@@ -6,6 +6,7 @@
 
 from typing import Any, Dict, List, Optional, Callable, Tuple
 from pathlib import Path
+from enum import Enum
 
 import absl
 import numpy as np
@@ -28,6 +29,12 @@
 from .base_workload_loader import BaseWorkloadLoader
 
 
+class TpchQueryDifficulty(Enum):
+    easy = {1, 3, 4, 6, 12, 14, 17, 19, 22}
+    medium = {10, 11, 13, 15, 16, 18, 20}
+    hard = {2, 7, 8, 9, 21}
+
+
 class TpchLoader:
     """Construct TPC-H task graph from a query profile
 
@@ -286,64 +293,104 @@ def __init__(self, flags: "absl.flags") -> None:
         # Instantiate tpch loader
         self._tpch_loader = TpchLoader(path=flags.tpch_query_dag_spec, flags=flags)
 
-        # Gather release times
-        release_policy = self.__make_release_policy()
-        release_times = release_policy.get_release_times(
-            completion_time=EventTime(self._flags.loop_timeout, EventTime.Unit.US)
-        )
+        # Intialize [(query_num, release_time)]
+        self._query_nums_and_release_times = []
+        if len(flags.override_num_invocations) > 0:
+            # One each for easy, medium, and hard
+            assert len(flags.override_num_invocations) == len(TpchQueryDifficulty)
+            assert len(flags.override_poisson_arrival_rates) == len(
+                flags.override_num_invocations
+            )
 
-        # Sample queries to be released
-        query_nums = [
-            self._rng.randint(1, self._tpch_loader.num_queries)
-            for _ in range(self._flags.override_num_invocation)
-        ]
+            # only works with poisson distribution
+            assert flags.override_release_policy == "poisson"
+
+            for i, part in enumerate(TpchQueryDifficulty):
+                print(flags.override_poisson_arrival_rates[i])
+                release_policy = self.__make_release_policy(
+                    policy_type=flags.override_release_policy,
+                    arrival_rate=float(flags.override_poisson_arrival_rates[i]),
+                    num_invocations=int(flags.override_num_invocations[i]),
+                )
+                release_times = release_policy.get_release_times(
+                    completion_time=EventTime(
+                        self._flags.loop_timeout, EventTime.Unit.US
+                    )
+                )
+                query_nums = [
+                    self._rng.choice(list(part.value))
+                    for _ in range(int(flags.override_num_invocations[i]))
+                ]
+                self._query_nums_and_release_times.extend(
+                    list(zip(query_nums, release_times))
+                )
+
+            self._query_nums_and_release_times.sort(key=lambda x: x[1])
+        else:
+            release_policy = self.__make_release_policy()
+            release_times = release_policy.get_release_times(
+                completion_time=EventTime(self._flags.loop_timeout, EventTime.Unit.US)
+            )
+            query_nums = [
+                self._rng.randint(1, self._tpch_loader.num_queries)
+                for _ in range(self._flags.override_num_invocation)
+            ]
+            self._query_nums_and_release_times.extend(
+                list(zip(query_nums, release_times))
+            )
 
-        self._query_nums_and_release_times = list(zip(query_nums, release_times))
         self._current_release_pointer = 0
 
         # Initialize workload
         self._workload = Workload.empty(flags)
 
-    def __make_release_policy(self):
+    def __make_release_policy(
+        self, policy_type=None, arrival_rate=None, num_invocations=None
+    ):
+        if policy_type is None:
+            policy_type = self._flags.override_release_policy
+        if arrival_rate is None:
+            arrival_rate = self._flags.override_poisson_arrival_rate
+        if num_invocations is None:
+            num_invocations = self._flags.override_num_invocation
+
         release_policy_args = {}
-        if self._flags.override_release_policy == "periodic":
+        if policy_type == "periodic":
             release_policy_args = {
                 "period": EventTime(
                     self._flags.override_arrival_period, EventTime.Unit.US
                 ),
             }
-        elif self._flags.override_release_policy == "fixed":
+        elif policy_type == "fixed":
             release_policy_args = {
                 "period": EventTime(
                     self._flags.override_arrival_period, EventTime.Unit.US
                 ),
-                "num_invocations": self._flags.override_num_invocation,
+                "num_invocations": num_invocations,
             }
-        elif self._flags.override_release_policy == "poisson":
+        elif policy_type == "poisson":
             release_policy_args = {
-                "rate": self._flags.override_poisson_arrival_rate,
-                "num_invocations": self._flags.override_num_invocation,
+                "rate": arrival_rate,
+                "num_invocations": num_invocations,
             }
-        elif self._flags.override_release_policy == "gamma":
+        elif policy_type == "gamma":
             release_policy_args = {
-                "rate": self._flags.override_poisson_arrival_rate,
-                "num_invocations": self._flags.override_num_invocation,
+                "rate": arrival_rate,
+                "num_invocations": num_invocations,
                 "coefficient": self._flags.override_gamma_coefficient,
             }
-        elif self._flags.override_release_policy == "fixed_gamma":
+        elif policy_type == "fixed_gamma":
             release_policy_args = {
-                "variable_arrival_rate": self._flags.override_poisson_arrival_rate,
+                "variable_arrival_rate": arrival_rate,
                 "base_arrival_rate": self._flags.override_base_arrival_rate,
-                "num_invocations": self._flags.override_num_invocation,
+                "num_invocations": num_invocations,
                 "coefficient": self._flags.override_gamma_coefficient,
             }
         else:
-            raise NotImplementedError(
-                f"Release policy {self._flags.override_release_policy} not implemented."
-            )
+            raise NotImplementedError(f"Release policy {policy_type} not implemented.")
 
         return make_release_policy(
-            self._flags.override_release_policy,
+            policy_type,
             release_policy_args,
             self._rng,
             self._rng_seed,