diff --git a/integ-test/src/test/java/org/opensearch/sql/calcite/big5/CalcitePPLBig5IT.java b/integ-test/src/test/java/org/opensearch/sql/calcite/big5/CalcitePPLBig5IT.java
index 665b3f0a874..f98b51d1c03 100644
--- a/integ-test/src/test/java/org/opensearch/sql/calcite/big5/CalcitePPLBig5IT.java
+++ b/integ-test/src/test/java/org/opensearch/sql/calcite/big5/CalcitePPLBig5IT.java
@@ -5,6 +5,8 @@
 
 package org.opensearch.sql.calcite.big5;
 
+import static org.opensearch.sql.util.MatcherUtils.assertYamlEqualsIgnoreId;
+
 import java.io.IOException;
 import org.junit.FixMethodOrder;
 import org.junit.Test;
@@ -42,4 +44,13 @@ public void coalesce_nonexistent_field_fallback() throws IOException {
     String ppl = sanitize(loadExpectedQuery("coalesce_nonexistent_field_fallback.ppl"));
     timing(summary, "coalesce_nonexistent_field_fallback", ppl);
   }
+
+  /** Tests deduplication by metrics.size field with sorting by timestamp. */
+  @Test
+  public void dedup_metrics_size_field() throws IOException {
+    String ppl = sanitize(loadExpectedQuery("dedup_metrics_size_field.ppl"));
+    timing(summary, "dedup_metrics_size_field", ppl);
+    String expected = loadExpectedPlan("big5/dedup_metrics_size_field.yaml");
+    assertYamlEqualsIgnoreId(expected, explainQueryYaml(ppl));
+  }
 }
diff --git a/integ-test/src/test/resources/big5/queries/dedup_metrics_size_field.ppl b/integ-test/src/test/resources/big5/queries/dedup_metrics_size_field.ppl
new file mode 100644
index 00000000000..bb55d3a06ed
--- /dev/null
+++ b/integ-test/src/test/resources/big5/queries/dedup_metrics_size_field.ppl
@@ -0,0 +1,22 @@
+/*
+{
+  "name": "dedup_metrics_size_field",
+  "operation-type": "search",
+  "index": "{{index_name | default('big5')}}",
+  "body": {
+    "query": {
+      "exists": {
+        "field": "metrics.size",
+        "boost": 1.0
+      }
+    },
+    "_source": {
+      "includes": ["agent", "process", "log", "message", "tags", "cloud", "input", "@timestamp", "ecs", "data_stream", "meta", "host", "metrics", "metrics.size", "aws", "event"],
+      "excludes": []
+    }
+  }
+}
+*/
+source = big5
+| dedup metrics.size
+| sort - @timestamp
\ No newline at end of file
diff --git a/integ-test/src/test/resources/expectedOutput/calcite/big5/dedup_metrics_size_field.yaml b/integ-test/src/test/resources/expectedOutput/calcite/big5/dedup_metrics_size_field.yaml
new file mode 100644
index 00000000000..9ab1bb342c9
--- /dev/null
+++ b/integ-test/src/test/resources/expectedOutput/calcite/big5/dedup_metrics_size_field.yaml
@@ -0,0 +1,14 @@
+calcite:
+  logical: |
+    LogicalSystemLimit(sort0=[$7], dir0=[DESC-nulls-last], fetch=[10000], type=[QUERY_SIZE_LIMIT])
+      LogicalProject(agent=[$0], process=[$6], log=[$8], message=[$11], tags=[$12], cloud=[$13], input=[$15], @timestamp=[$17], ecs=[$18], data_stream=[$20], meta=[$24], host=[$26], metrics=[$27], aws=[$30], event=[$35])
+        LogicalSort(sort0=[$17], dir0=[DESC-nulls-last])
+          LogicalProject(agent=[$0], agent.ephemeral_id=[$1], agent.id=[$2], agent.name=[$3], agent.type=[$4], agent.version=[$5], process=[$6], process.name=[$7], log=[$8], log.file=[$9], log.file.path=[$10], message=[$11], tags=[$12], cloud=[$13], cloud.region=[$14], input=[$15], input.type=[$16], @timestamp=[$17], ecs=[$18], ecs.version=[$19], data_stream=[$20], data_stream.dataset=[$21], data_stream.namespace=[$22], data_stream.type=[$23], meta=[$24], meta.file=[$25], host=[$26], metrics=[$27], metrics.size=[$28], metrics.tmin=[$29], aws=[$30], aws.cloudwatch=[$31], aws.cloudwatch.ingestion_time=[$32], aws.cloudwatch.log_group=[$33], aws.cloudwatch.log_stream=[$34], event=[$35], event.dataset=[$36], event.id=[$37], event.ingested=[$38], _id=[$39], _index=[$40], _score=[$41], _maxscore=[$42], _sort=[$43], _routing=[$44])
+            LogicalFilter(condition=[<=($45, 1)])
+              LogicalProject(agent=[$0], agent.ephemeral_id=[$1], agent.id=[$2], agent.name=[$3], agent.type=[$4], agent.version=[$5], process=[$6], process.name=[$7], log=[$8], log.file=[$9], log.file.path=[$10], message=[$11], tags=[$12], cloud=[$13], cloud.region=[$14], input=[$15], input.type=[$16], @timestamp=[$17], ecs=[$18], ecs.version=[$19], data_stream=[$20], data_stream.dataset=[$21], data_stream.namespace=[$22], data_stream.type=[$23], meta=[$24], meta.file=[$25], host=[$26], metrics=[$27], metrics.size=[$28], metrics.tmin=[$29], aws=[$30], aws.cloudwatch=[$31], aws.cloudwatch.ingestion_time=[$32], aws.cloudwatch.log_group=[$33], aws.cloudwatch.log_stream=[$34], event=[$35], event.dataset=[$36], event.id=[$37], event.ingested=[$38], _id=[$39], _index=[$40], _score=[$41], _maxscore=[$42], _sort=[$43], _routing=[$44], _row_number_dedup_=[ROW_NUMBER() OVER (PARTITION BY $28)])
+                LogicalFilter(condition=[IS NOT NULL($28)])
+                  CalciteLogicalIndexScan(table=[[OpenSearch, big5]])
+  physical: |
+    EnumerableLimit(fetch=[10000])
+      EnumerableSort(sort0=[$7], dir0=[DESC-nulls-last])
+        CalciteEnumerableIndexScan(table=[[OpenSearch, big5]], PushDownContext=[[AGGREGATION->rel#:LogicalAggregate.NONE.[](input=LogicalProject#,group={0},agg#0=LITERAL_AGG(1))], OpenSearchRequestBuilder(sourceBuilder={"from":0,"size":0,"timeout":"1m","aggregations":{"composite_buckets":{"composite":{"size":10000,"sources":[{"metrics.size":{"terms":{"field":"metrics.size","missing_bucket":false,"order":"asc"}}}]},"aggregations":{"$f1":{"top_hits":{"from":0,"size":1,"version":false,"seq_no_primary_term":false,"explain":false,"_source":{"includes":["metrics.size","agent","agent.ephemeral_id","agent.id","agent.name","agent.type","agent.version","process","process.name","log","log.file","log.file.path","message","tags","cloud","cloud.region","input","input.type","@timestamp","ecs","ecs.version","data_stream","data_stream.dataset","data_stream.namespace","data_stream.type","meta","meta.file","host","metrics","metrics.tmin","aws","aws.cloudwatch","aws.cloudwatch.ingestion_time","aws.cloudwatch.log_group","aws.cloudwatch.log_stream","event","event.dataset","event.id","event.ingested","_id","_index","_score","_maxscore","_sort","_routing"],"excludes":[]},"script_fields":{}}}}}}}, requestedTotalSize=2147483647, pageSize=null, startFrom=0)])
\ No newline at end of file
diff --git a/opensearch/src/main/java/org/opensearch/sql/opensearch/data/utils/ObjectContent.java b/opensearch/src/main/java/org/opensearch/sql/opensearch/data/utils/ObjectContent.java
index 9ca3deadddd..b409640c993 100644
--- a/opensearch/src/main/java/org/opensearch/sql/opensearch/data/utils/ObjectContent.java
+++ b/opensearch/src/main/java/org/opensearch/sql/opensearch/data/utils/ObjectContent.java
@@ -141,7 +141,7 @@ public boolean isBoolean() {
 
   @Override
   public boolean isArray() {
-    return value instanceof ArrayNode;
+    return value instanceof ArrayNode || value instanceof List;
   }
 
   @Override
diff --git a/opensearch/src/main/java/org/opensearch/sql/opensearch/data/value/OpenSearchExprValueFactory.java b/opensearch/src/main/java/org/opensearch/sql/opensearch/data/value/OpenSearchExprValueFactory.java
index 4e6032d4f1d..f31c4b67ae7 100644
--- a/opensearch/src/main/java/org/opensearch/sql/opensearch/data/value/OpenSearchExprValueFactory.java
+++ b/opensearch/src/main/java/org/opensearch/sql/opensearch/data/value/OpenSearchExprValueFactory.java
@@ -182,8 +182,7 @@ public ExprValue construct(String jsonString, boolean supportArrays) {
    * @return ExprValue
    */
   public ExprValue construct(String field, Object value, boolean supportArrays) {
-    Object extractedValue = extractFinalPrimitiveValue(value);
-    return parse(new ObjectContent(extractedValue), field, type(field), supportArrays);
+    return parse(new ObjectContent(value), field, type(field), supportArrays);
   }
 
   private ExprValue parse(
@@ -214,7 +213,9 @@ private ExprValue parse(
         || type == STRUCT) {
       return parseStruct(content, field, supportArrays);
     } else if (typeActionMap.containsKey(type)) {
-      return typeActionMap.get(type).apply(content, type);
+      return content.isArray()
+          ? parseArray(content, field, type, supportArrays)
+          : typeActionMap.get(type).apply(content, type);
     } else {
       throw new IllegalStateException(
           String.format(
@@ -581,26 +582,4 @@ private ExprValue parseInnerArrayValue(
   private String makeField(String path, String field) {
     return path.equalsIgnoreCase(TOP_PATH) ? field : String.join(".", path, field);
   }
-
-  /**
-   * Recursively extracts the final primitive value from nested Map structures. For example:
-   * {attributes={telemetry={sdk={language=java}}}} -> "java"
-   *
-   * @param value The value to extract from
-   * @return The extracted primitive value, or the original value if extraction is not possible
-   */
-  @SuppressWarnings("unchecked")
-  private Object extractFinalPrimitiveValue(Object value) {
-    if (value == null || !(value instanceof Map)) {
-      return value;
-    }
-
-    Map<String, Object> map = (Map<String, Object>) value;
-    if (map.size() == 1) {
-      Object singleValue = map.values().iterator().next();
-      return extractFinalPrimitiveValue(singleValue);
-    }
-
-    return value;
-  }
 }
diff --git a/opensearch/src/main/java/org/opensearch/sql/opensearch/planner/rules/DedupPushdownRule.java b/opensearch/src/main/java/org/opensearch/sql/opensearch/planner/rules/DedupPushdownRule.java
index 28e4bc16001..5b64d8fc197 100644
--- a/opensearch/src/main/java/org/opensearch/sql/opensearch/planner/rules/DedupPushdownRule.java
+++ b/opensearch/src/main/java/org/opensearch/sql/opensearch/planner/rules/DedupPushdownRule.java
@@ -93,7 +93,7 @@ protected void apply(
                         .filter(pair -> ((RexInputRef) pair.getKey()).getIndex() == i)
                         .map(Pair::getValue)
                         .findFirst()
-                        .get())
+                        .orElse(projectWithWindow.getInput().getRowType().getFieldNames().get(i)))
             .collect(Collectors.toList());
     if (dedupColumnIndices.size() != dedupColumnNames.size()) {
       return;