Fix: chunk number error after re-parsing (#8513)

### What problem does this PR solve?

Fix chunk number error after re-parsing. #8503.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/db/services/document_service.py

@@ -279,6 +279,24 @@ class DocumentService(CommonService):
             Knowledgebase.id == doc.kb_id).execute()
         return num
 
+
+    @classmethod
+    @DB.connection_context()
+    def clear_chunk_num_when_rerun(cls, doc_id):
+        doc = cls.model.get_by_id(doc_id)
+        assert doc, "Can't fine document in database."
+
+        num = (
+            Knowledgebase.update(
+                token_num=Knowledgebase.token_num - doc.token_num,
+                chunk_num=Knowledgebase.chunk_num - doc.chunk_num,
+            )
+            .where(Knowledgebase.id == doc.kb_id)
+            .execute()
+        )
+        return num
+
+
     @classmethod
     @DB.connection_context()
     def get_tenant_id(cls, doc_id):