fixing the single quoted literal in window function

pinot-integration-tests/src/test/java/org/apache/pinot/integration/tests/OfflineClusterIntegrationTest.java

@@ -2156,6 +2156,42 @@ public void testWindowAggregationV2()
       assertEquals(rows.get(i - 2).get(1).asLong(), row.get(2).asLong());
       assertEquals(row.get(1).asLong() - row.get(2).asLong(), row.get(3).asLong());
     }
+
+    query = "WITH tmp AS (\n"
+        + "  select count(*) as num_trips, DaysSinceEpoch  from mytable GROUP BY DaysSinceEpoch\n"
+        + ")\n"
+        + "\n"
+        + "SELECT\n"
+        + "    DaysSinceEpoch,\n"
+        + "    num_trips,\n"
+        + "    LAG(num_trips, '2') OVER (ORDER BY DaysSinceEpoch) AS previous_num_trips,\n"
+        + "    num_trips - LAG(num_trips, '2') OVER (ORDER BY DaysSinceEpoch) AS difference\n"
+        + "FROM\n"
+        + "    tmp";
+    response = postQuery(query);
+    resultTable = response.get("resultTable");
+    assertEquals(resultTable.get("dataSchema").get("columnDataTypes").toString(),
+        "[\"INT\",\"LONG\",\"LONG\",\"LONG\"]");
+    rows = resultTable.get("rows");
+    assertEquals(rows.size(), 364);
+    for (int i = 0; i < 2; i++) {
+      JsonNode row = rows.get(i);
+      JsonNode tmpTableRow = tmpTableResult.get(i);
+      assertEquals(row.size(), 4);
+      assertEquals(row.get(0).asInt(), tmpTableRow.get(0).asInt());
+      assertEquals(row.get(1).asLong(), tmpTableRow.get(1).asLong());
+      assertTrue(row.get(2).isNull());
+      assertTrue(row.get(2).isNull());
+    }
+    for (int i = 2; i < 363; i++) {
+      JsonNode row = rows.get(i);
+      assertEquals(row.size(), 4);
+      JsonNode tmpTableRow = tmpTableResult.get(i);
+      assertEquals(row.get(0).asInt(), tmpTableRow.get(0).asInt());
+      assertEquals(row.get(1).asLong(), tmpTableRow.get(1).asLong());
+      assertEquals(rows.get(i - 2).get(1).asLong(), row.get(2).asLong());
+      assertEquals(row.get(1).asLong() - row.get(2).asLong(), row.get(3).asLong());
+    }
   }
 
   @Test(dataProvider = "useBothQueryEngines")

pinot-query-planner/src/main/java/org/apache/pinot/calcite/rel/rules/PinotWindowExchangeNodeInsertRule.java

@@ -40,6 +40,7 @@
 import org.apache.calcite.rel.type.RelDataTypeField;
 import org.apache.calcite.rex.RexBuilder;
 import org.apache.calcite.rex.RexInputRef;
+import org.apache.calcite.rex.RexLiteral;
 import org.apache.calcite.rex.RexNode;
 import org.apache.calcite.sql.SqlAggFunction;
 import org.apache.calcite.sql.SqlKind;
@@ -172,6 +173,17 @@ private Window.Group updateLiteralArgumentsInWindowGroup(Window window) {
             newRexNode = window.constants.get(inputRefIndex - windowInputSize);
             changed = true;
             aggCallChanged = true;
+          } else {
+            RelNode windowInputRelNode = ((HepRelVertex) window.getInput()).getCurrentRel();
+            if (windowInputRelNode instanceof LogicalProject) {
+              RexNode inputRefRexNode = ((LogicalProject) windowInputRelNode).getProjects().get(inputRefIndex);
+              if (inputRefRexNode instanceof RexLiteral) {
+                // If the input reference is a literal, replace it with the literal value
+                newRexNode = inputRefRexNode;
+                changed = true;
+                aggCallChanged = true;
+              }
+            }
           }
         }
         rexList.add(newRexNode);