diff --git a/lightrag/operate.py b/lightrag/operate.py
index 1e2a9ddb..22e49066 100644
--- a/lightrag/operate.py
+++ b/lightrag/operate.py
@@ -2870,7 +2870,7 @@ async def _apply_token_truncation(
 
         entities_context.append(
             {
-                "id": i + 1,
+                "id": f"EN{i + 1}",
                 "entity": entity_name,
                 "type": entity.get("entity_type", "UNKNOWN"),
                 "description": entity.get("description", "UNKNOWN"),
@@ -2898,7 +2898,7 @@ async def _apply_token_truncation(
 
         relations_context.append(
             {
-                "id": i + 1,
+                "id": f"RE{i + 1}",
                 "entity1": entity1,
                 "entity2": entity2,
                 "description": relation.get("description", "UNKNOWN"),
@@ -3246,7 +3246,7 @@ async def _build_llm_context(
         for i, chunk in enumerate(truncated_chunks):
             text_units_context.append(
                 {
-                    "id": i + 1,
+                    "id": chunk["id"],
                     "content": chunk["content"],
                     "file_path": chunk.get("file_path", "unknown_source"),
                 }
@@ -4216,7 +4216,7 @@ async def naive_query(
     for i, chunk in enumerate(processed_chunks):
         text_units_context.append(
             {
-                "id": i + 1,
+                "id": chunk["id"],
                 "content": chunk["content"],
                 "file_path": chunk.get("file_path", "unknown_source"),
             }
diff --git a/lightrag/utils.py b/lightrag/utils.py
index 504a830a..7692cb2a 100644
--- a/lightrag/utils.py
+++ b/lightrag/utils.py
@@ -2455,7 +2455,14 @@ async def process_chunks_unified(
             f"(chunk available tokens: {chunk_token_limit}, source: {source_type})"
         )
 
-    return unique_chunks
+    # 5. add id field to each chunk
+    final_chunks = []
+    for i, chunk in enumerate(unique_chunks):
+        chunk_with_id = chunk.copy()
+        chunk_with_id["id"] = f"DC{i + 1}"
+        final_chunks.append(chunk_with_id)
+
+    return final_chunks
 
 
 def build_file_path(already_file_paths, data_list, target):