From 9b76d13ff8f481b815b195aacb1612b7a789d868 Mon Sep 17 00:00:00 2001
From: Sree Charan Manamala <sree.manamala@imply.io>
Date: Fri, 26 Jul 2024 14:48:35 +0530
Subject: [PATCH] Check for Aggregation inside a window clause when syntax used
 as - WINDOW W AS DEF (#16801)

---
 .../calcite/planner/DruidSqlValidator.java    | 16 ++++++++++++++++
 .../druid/sql/calcite/CalciteQueryTest.java   | 19 +++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidSqlValidator.java b/sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidSqlValidator.java
index e00a2915a2e8..16d3541e96c6 100644
--- a/sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidSqlValidator.java
+++ b/sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidSqlValidator.java
@@ -796,6 +796,22 @@ public void validateCall(SqlCall call, SqlValidatorScope scope)
     super.validateCall(call, scope);
   }
 
+  @Override
+  protected void validateWindowClause(SqlSelect select)
+  {
+    SqlNodeList windows = select.getWindowList();
+    for (SqlNode sqlNode : windows) {
+      if (SqlUtil.containsAgg(sqlNode)) {
+        throw buildCalciteContextException(
+            "Aggregation inside window is currently not supported with syntax WINDOW W AS <DEF>. "
+            + "Try providing window definition directly without alias",
+            sqlNode
+        );
+      }
+    }
+    super.validateWindowClause(select);
+  }
+
   @Override
   protected SqlNode performUnconditionalRewrites(SqlNode node, final boolean underFrom)
   {
diff --git a/sql/src/test/java/org/apache/druid/sql/calcite/CalciteQueryTest.java b/sql/src/test/java/org/apache/druid/sql/calcite/CalciteQueryTest.java
index 5ceba91eb37c..84b437c20e08 100644
--- a/sql/src/test/java/org/apache/druid/sql/calcite/CalciteQueryTest.java
+++ b/sql/src/test/java/org/apache/druid/sql/calcite/CalciteQueryTest.java
@@ -25,6 +25,7 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
+import org.apache.calcite.rel.RelNode;
 import org.apache.calcite.runtime.CalciteContextException;
 import org.apache.druid.common.config.NullHandling;
 import org.apache.druid.error.DruidException;
@@ -149,6 +150,7 @@
 import java.util.stream.Collectors;
 
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assumptions.assumeFalse;
@@ -15592,6 +15594,23 @@ public void testDistinctNotSupportedWithWindow()
     assertThat(e, invalidSqlContains("DISTINCT is not supported for window functions"));
   }
 
+  @Test
+  public void testUnSupportedAggInSelectWindow()
+  {
+    assertEquals(
+        "1.37.0",
+        RelNode.class.getPackage().getImplementationVersion(),
+        "Calcite version changed; check if CALCITE-6500 is fixed and update:\n * method DruidSqlValidator#validateWindowClause"
+    );
+
+    DruidException e = assertThrows(DruidException.class, () -> testBuilder()
+        .queryContext(ImmutableMap.of(PlannerContext.CTX_ENABLE_WINDOW_FNS, true))
+        .sql("SELECT dim1, ROW_NUMBER() OVER W from druid.foo WINDOW W as (ORDER BY max(length(dim1)))")
+        .run());
+
+    assertThat(e, invalidSqlContains("not supported with syntax WINDOW W AS <DEF>"));
+  }
+
   @Test
   public void testInGroupByLimitOutGroupByOrderBy()
   {