Merge remote-tracking branch 'upstream/develop' into issue/opensearch…

…-project#100

Signed-off-by: chloe-zh <chloezh1102@gmail.com>

# Conflicts:
#	opensearch/src/main/java/org/opensearch/sql/opensearch/storage/script/aggregation/dsl/MetricAggregationBuilder.java

opensearch/src/main/java/org/opensearch/sql/opensearch/storage/script/aggregation/dsl/MetricAggregationBuilder.java

@@ -99,7 +99,10 @@ public Pair<AggregationBuilder, MetricParser> visitNamedAggregator(
     if (distinct) {
       switch (node.getFunctionName().getFunctionName()) {
         case "count":
-          return make(AggregationBuilders.cardinality(name), expression);
+          return make(
+              AggregationBuilders.cardinality(name),
+              expression,
+              new SingleValueParser(name));
         default:
           throw new ExpressionEvaluationException(String.format(
               "unsupported distinct aggregator %s", node.getFunctionName().getFunctionName()));
@@ -171,6 +174,12 @@ private AggregationBuilder make(CardinalityAggregationBuilder builder, Expressio
     return cardinalityHelper.build(expression, builder::field, builder::script);
   }
 
+  private Pair<AggregationBuilder, MetricParser> make(CardinalityAggregationBuilder builder,
+                                                      Expression expression,
+                                                      MetricParser parser) {
+    return Pair.of(cardinalityHelper.build(expression, builder::field, builder::script), parser);
+  }
+
   /**
    * Replace star or literal with OpenSearch metadata field "_index". Because: 1) Analyzer already
    * converts * to string literal, literal check here can handle both COUNT(*) and COUNT(1). 2)