Sort earliest results with asc order

Signed-off-by: Yuanchun Shen <yuanchu@amazon.com>

Author: yuancu

core/src/main/java/org/opensearch/sql/calcite/CalciteRelNodeVisitor.java

@@ -2268,8 +2268,11 @@ private RelNode buildTopCategoriesQuery(
 
     // Apply sorting and limit to non-null categories only
     RexNode sortField = context.relBuilder.field("grand_total");
+    // For MIN and EARLIEST, top results should be the minimum ones
     sortField =
-        aggFunction == BuiltinFunctionName.MIN ? sortField : context.relBuilder.desc(sortField);
+        aggFunction == BuiltinFunctionName.MIN || aggFunction == BuiltinFunctionName.EARLIEST
+            ? sortField
+            : context.relBuilder.desc(sortField);
     context.relBuilder.sort(sortField);
     if (limit > 0) {
       context.relBuilder.limit(0, limit);

integ-test/src/yamlRestTest/resources/rest-api-spec/test/issues/4582.yml

@@ -98,9 +98,9 @@ teardown:
   - match: { total: 3 }
   - match: { "schema": [{"name": "@timestamp", "type": "timestamp"}, {"name": "severityText", "type": "string"}, {"name": "earliest(@timestamp)", "type": "timestamp"}] }
   - match: { "datarows": [
-    ["2024-01-15 10:30:00", "CUSTOM", "2024-01-15 10:30:11.567890123"],
-    ["2024-01-15 10:30:00", "OTHER", "2024-01-15 10:30:04.567890123"],
-    ["2024-01-15 10:30:00", "TRACE", "2024-01-15 10:30:10.567890123"]] }
+    ["2024-01-15 10:30:00", "INFO", "2024-01-15 10:30:04.567890123"],
+    ["2024-01-15 10:30:00", "OTHER", "2024-01-15 10:30:06.567890123"],
+    ["2024-01-15 10:30:00", "WARN", "2024-01-15 10:30:05.567890123"]] }
 
 ---
 "timechart count aggregation with limit should sum OTHER values":