diff --git a/src/execution/mock_scan_executor.cpp b/src/execution/mock_scan_executor.cpp
index 306de5e60..0527b254d 100644
--- a/src/execution/mock_scan_executor.cpp
+++ b/src/execution/mock_scan_executor.cpp
@@ -53,7 +53,9 @@ const char *mock_table_list[] = {"__mock_table_1", "__mock_table_2", "__mock_tab
                                  // For leaderboard Q2
                                  "__mock_t4_1m", "__mock_t5_1m", "__mock_t6_1m",
                                  // For leaderboard Q3
-                                 "__mock_t7", "__mock_t8", "__mock_t9", nullptr};
+                                 "__mock_t7", "__mock_t8", "__mock_t9",
+                                 // For P3 leaderboard Q4
+                                 "__mock_t10", "__mock_t11", nullptr};
 
 static const int GRAPH_NODE_CNT = 10;
 
@@ -128,6 +130,14 @@ auto GetMockTableSchemaOf(const std::string &table) -> Schema {
     return Schema{std::vector{Column{"x", TypeId::INTEGER}, Column{"y", TypeId::INTEGER}}};
   }
 
+  if (table == "__mock_t10") {
+    return Schema{std::vector{Column{"x", TypeId::INTEGER}, Column{"y", TypeId::INTEGER}}};
+  }
+
+  if (table == "__mock_t11") {
+    return Schema{std::vector{Column{"x", TypeId::INTEGER}, Column{"y", TypeId::INTEGER}}};
+  }
+
   throw bustub::Exception(fmt::format("mock table {} not found", table));
 }
 
@@ -202,6 +212,14 @@ auto GetSizeOf(const MockScanPlanNode *plan) -> size_t {
     return 10000000;
   }
 
+  if (table == "__mock_t10") {
+    return 10000;  // 10k
+  }
+
+  if (table == "__mock_t11") {
+    return 1000000;  // 1M
+  }
+
   return 0;
 }
 
@@ -428,6 +446,24 @@ auto GetFunctionOf(const MockScanPlanNode *plan) -> std::function<Tuple(size_t)>
     };
   }
 
+  if (table == "__mock_t10") {
+    return [plan](size_t cursor) {
+      std::vector<Value> values{};
+      values.push_back(ValueFactory::GetIntegerValue(cursor));
+      values.push_back(ValueFactory::GetIntegerValue(cursor * 10));
+      return Tuple{values, &plan->OutputSchema()};
+    };
+  }
+
+  if (table == "__mock_t11") {
+    return [plan](size_t cursor) {
+      std::vector<Value> values{};
+      values.push_back(ValueFactory::GetIntegerValue(-1 * (cursor % 1000) - 1));
+      values.push_back(ValueFactory::GetIntegerValue(cursor * 10));
+      return Tuple{values, &plan->OutputSchema()};
+    };
+  }
+
   // By default, return table of all 0.
   return [plan](size_t cursor) {
     std::vector<Value> values{};
diff --git a/test/sql/p3.leaderboard-q4.slt b/test/sql/p3.leaderboard-q4.slt
new file mode 100644
index 000000000..86933563c
--- /dev/null
+++ b/test/sql/p3.leaderboard-q4.slt
@@ -0,0 +1,3 @@
+query rowsort +timing:x20:.q1
+select * from __mock_t10 a join __mock_t11 b on a.x = b.x;
+----
\ No newline at end of file