simplified code

Signed-off-by: xinyual <xinyual@amazon.com>

Author: xinyual

integ-test/src/test/java/org/opensearch/sql/calcite/standalone/CalcitePPLBasicIT.java

@@ -566,23 +566,19 @@ public void testMetaFieldAlias() {
   }
 
   @Test
-  public void testMergeTwoObject() {
-    JSONObject result =
-        executeQuery(
-            String.format("source=%s | fields machine.os1 ", TEST_INDEX_MERGE_TEST_WILDCARD));
-    verifySchema(result, schema("original_col", "integer"), schema("alias_col", "integer"));
-    verifyDataRows(result, rows(2, 2), rows(3, 3));
-  }
-
-  @Test
-  public void testMergeTwoObjectReturn() {
+  public void testFieldsMergedObject() {
     JSONObject result =
         executeQuery(
             String.format(
                 "source=%s | fields machine.os1,  machine.os2, machine_array.os1, "
                     + " machine_array.os2",
                 TEST_INDEX_MERGE_TEST_WILDCARD));
-    verifySchema(result, schema("original_col", "integer"), schema("alias_col", "integer"));
-    verifyDataRows(result, rows(2, 2), rows(3, 3));
+    verifySchema(
+        result,
+        schema("machine.os1", "string"),
+        schema("machine.os2", "string"),
+        schema("machine_array.os1", "string"),
+        schema("machine_array.os2", "string"));
+    verifyDataRows(result, rows("linux", null, "linux", null), rows(null, "linux", null, "linux"));
   }
 }

integ-test/src/test/java/org/opensearch/sql/ppl/FieldsCommandIT.java

@@ -5,8 +5,7 @@
 
 package org.opensearch.sql.ppl;
 
-import static org.opensearch.sql.legacy.TestsConstants.TEST_INDEX_ACCOUNT;
-import static org.opensearch.sql.legacy.TestsConstants.TEST_INDEX_BANK;
+import static org.opensearch.sql.legacy.TestsConstants.*;
 import static org.opensearch.sql.util.MatcherUtils.columnName;
 import static org.opensearch.sql.util.MatcherUtils.columnPattern;
 import static org.opensearch.sql.util.MatcherUtils.rows;
@@ -28,6 +27,8 @@ public void init() throws Exception {
     super.init();
     loadIndex(Index.ACCOUNT);
     loadIndex(Index.BANK);
+    loadIndex(Index.MERGE_TEST_1);
+    loadIndex(Index.MERGE_TEST_2);
   }
 
   @Test
@@ -105,4 +106,21 @@ public void testMetadataFieldsWithEvalMetaField() {
                         "source=%s | eval _id = 1 | fields firstname, _id", TEST_INDEX_ACCOUNT)));
     verifyErrorMessageContains(e, "Cannot use metadata field [_id] as the eval field.");
   }
+
+  @Test
+  public void testFieldsTwoMergedObject() throws IOException {
+    JSONObject result =
+        executeQuery(
+            String.format(
+                "source=%s | fields machine.os1,  machine.os2, machine_array.os1, "
+                    + " machine_array.os2",
+                TEST_INDEX_MERGE_TEST_WILDCARD));
+    verifySchema(
+        result,
+        schema("machine.os1", "string"),
+        schema("machine.os2", "string"),
+        schema("machine_array.os1", "string"),
+        schema("machine_array.os2", "string"));
+    verifyDataRows(result, rows("linux", null, "linux", null), rows(null, "linux", null, "linux"));
+  }
 }

opensearch/src/main/java/org/opensearch/sql/opensearch/request/system/OpenSearchDescribeIndexRequest.java

@@ -15,6 +15,7 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import lombok.extern.log4j.Log4j2;
 import org.opensearch.sql.data.model.ExprTupleValue;
 import org.opensearch.sql.data.model.ExprValue;
 import org.opensearch.sql.data.type.ExprCoreType;
@@ -25,6 +26,7 @@
 import org.opensearch.sql.opensearch.mapping.IndexMapping;
 import org.opensearch.sql.opensearch.request.OpenSearchRequest;
 
+@Log4j2
 /** Describe index meta data request. */
 public class OpenSearchDescribeIndexRequest implements OpenSearchSystemRequest {
 
@@ -100,40 +102,27 @@ public Map<String, OpenSearchDataType> getFieldTypes() {
     Map<String, OpenSearchDataType> fieldTypes = new HashMap<>();
     Map<String, IndexMapping> indexMappings =
         client.getIndexMappings(getLocalIndexNames(indexName.getIndexNames()));
+    log.error(indexMappings.keySet());
     for (IndexMapping indexMapping : indexMappings.values()) {
-      addIndexMapping(fieldTypes, indexMapping.getFieldMappings());
+      mergeObjectAndArrayInsideMap(fieldTypes, indexMapping.getFieldMappings());
     }
     return fieldTypes;
   }
 
-  private void addIndexMapping(
-      Map<String, OpenSearchDataType> resultMap, Map<String, OpenSearchDataType> candidateMap) {
-    for (Map.Entry<String, OpenSearchDataType> entry : candidateMap.entrySet()) {
-      if (resultMap.containsKey(entry.getKey())
-          && checkWhetherToMerge(entry.getValue(), resultMap.get(entry.getKey()))) {
-        resultMap.put(
-            entry.getKey(), mergetTwoObject(resultMap.get(entry.getKey()), entry.getValue()));
-      } else {
-        resultMap.put(entry.getKey(), entry.getValue());
-      }
-    }
-  }
+  private void mergeObjectAndArrayInsideMap(
+      Map<String, OpenSearchDataType> target, Map<String, OpenSearchDataType> source) {
+    for (Map.Entry<String, OpenSearchDataType> entry : source.entrySet()) {
+      String key = entry.getKey();
+      OpenSearchDataType value = entry.getValue();
 
-  private OpenSearchDataType mergetTwoObject(OpenSearchDataType first, OpenSearchDataType second) {
-    Map<String, OpenSearchDataType> candidateMap = second.getProperties();
-    for (Map.Entry<String, OpenSearchDataType> entry : candidateMap.entrySet()) {
-      if (first.getProperties().containsKey(entry.getKey())
-          && checkWhetherToMerge(entry.getValue(), first.getProperties().get(entry.getKey()))) {
-        first
-            .getProperties()
-            .put(
-                entry.getKey(),
-                mergetTwoObject(first.getProperties().get(entry.getKey()), entry.getValue()));
+      if (target.containsKey(key) && checkWhetherToMerge(value, target.get(key))) {
+        OpenSearchDataType merged = target.get(key);
+        mergeObjectAndArrayInsideMap(merged.getProperties(), value.getProperties());
+        target.put(key, merged);
       } else {
-        first.getProperties().put(entry.getKey(), entry.getValue());
+        target.put(key, value);
       }
     }
-    return first;
   }
 
   private Boolean checkWhetherToMerge(OpenSearchDataType first, OpenSearchDataType second) {