[GLUTEN-7778][CH] Make aggregation output schema same as CH native

backends-clickhouse/src/main/scala/org/apache/gluten/backendsapi/clickhouse/CHSparkPlanExecApi.scala

@@ -158,16 +158,21 @@ class CHSparkPlanExecApi extends SparkPlanExecApi with Logging {
       aggregateAttributes: Seq[Attribute],
       initialInputBufferOffset: Int,
       resultExpressions: Seq[NamedExpression],
-      child: SparkPlan): HashAggregateExecBaseTransformer =
+      child: SparkPlan): HashAggregateExecBaseTransformer = {
+    val replacedResultExpressions = CHHashAggregateExecTransformer.getCHAggregateResultExpressions(
+      groupingExpressions,
+      aggregateExpressions,
+      resultExpressions)
     CHHashAggregateExecTransformer(
       requiredChildDistributionExpressions,
       groupingExpressions.distinct,
       aggregateExpressions,
       aggregateAttributes,
       initialInputBufferOffset,
-      resultExpressions.distinct,
+      replacedResultExpressions.distinct,
       child
     )
+  }
 
   /** Generate HashAggregateExecPullOutHelper */
   override def genHashAggregateExecPullOutHelper(

backends-clickhouse/src/main/scala/org/apache/gluten/backendsapi/clickhouse/CHTransformerApi.scala

@@ -177,10 +177,13 @@ class CHTransformerApi extends TransformerApi with Logging {
         // output name will be different from grouping expressions,
         // so using output attribute instead of grouping expression
         val groupingExpressions = hash.output.splitAt(hash.groupingExpressions.size)._1
-        val aggResultAttributes = CHHashAggregateExecTransformer.getAggregateResultAttributes(
-          groupingExpressions,
-          hash.aggregateExpressions
-        )
+        val aggResultAttributes = CHHashAggregateExecTransformer
+          .getCHAggregateResultExpressions(
+            groupingExpressions,
+            hash.aggregateExpressions,
+            hash.resultExpressions
+          )
+          .map(_.toAttribute)
         if (aggResultAttributes.size == hash.output.size) {
           aggResultAttributes
         } else {

backends-clickhouse/src/main/scala/org/apache/gluten/execution/CHHashAggregateExecTransformer.scala

@@ -43,6 +43,45 @@ import scala.collection.JavaConverters._
 import scala.collection.mutable.ListBuffer
 
 object CHHashAggregateExecTransformer {
+  // The result attributes of aggregate expressions from vanilla may be different from CH native.
+  // For example, the result attributes of `avg(x)` are `sum(x)` and `count(x)`. This could bring
+  // some unexpected issues. So we need to make the result attributes consistent with CH native.
+  def getCHAggregateResultExpressions(
+      groupingExpressions: Seq[NamedExpression],
+      aggregateExpressions: Seq[AggregateExpression],
+      resultExpressions: Seq[NamedExpression]): Seq[NamedExpression] = {
+    var adjustedResultExpressions = resultExpressions.slice(0, groupingExpressions.length)
+    var resultExpressionIndex = groupingExpressions.length
+    adjustedResultExpressions ++ aggregateExpressions.flatMap {
+      aggExpr =>
+        aggExpr.mode match {
+          case Partial | PartialMerge =>
+            // For partial aggregate, the size of the result expressions of an aggregate expression
+            // is the same as aggBufferAttributes' length
+            val aggBufferAttributesCount = aggExpr.aggregateFunction.aggBufferAttributes.length
+            aggExpr.aggregateFunction match {
+              case avg: Average =>
+                val res = Seq(aggExpr.resultAttribute)
+                resultExpressionIndex += aggBufferAttributesCount
+                res
+              case sum: Sum if (sum.dataType.isInstanceOf[DecimalType]) =>
+                val res = Seq(resultExpressions(resultExpressionIndex))
+                resultExpressionIndex += aggBufferAttributesCount
+                res
+              case _ =>
+                val res = resultExpressions
+                  .slice(resultExpressionIndex, resultExpressionIndex + aggBufferAttributesCount)
+                resultExpressionIndex += aggBufferAttributesCount
+                res
+            }
+          case _ =>
+            val res = Seq(resultExpressions(resultExpressionIndex))
+            resultExpressionIndex += 1
+            res
+        }
+    }
+  }
+
   def getAggregateResultAttributes(
       groupingExpressions: Seq[NamedExpression],
       aggregateExpressions: Seq[AggregateExpression]): Seq[Attribute] = {