diff --git a/src/pai_rag/integrations/vector_stores/postgresql/postgresql.py b/src/pai_rag/integrations/vector_stores/postgresql/postgresql.py
index 50f950d0..e1f286ea 100644
--- a/src/pai_rag/integrations/vector_stores/postgresql/postgresql.py
+++ b/src/pai_rag/integrations/vector_stores/postgresql/postgresql.py
@@ -71,7 +71,7 @@ class HybridAbstractData(base):  # type: ignore
             id = Column(BIGINT, primary_key=True, autoincrement=True)
             text = Column(VARCHAR, nullable=False)
             metadata_ = Column(metadata_dtype)
-            node_id = Column(VARCHAR)
+            node_id = Column(VARCHAR, unique=True)
             embedding = Column(Vector(embed_dim))  # type: ignore
             text_search_tsv = Column(  # type: ignore
                 TSVector(),
@@ -98,7 +98,7 @@ class AbstractData(base):  # type: ignore
             id = Column(BIGINT, primary_key=True, autoincrement=True)
             text = Column(VARCHAR, nullable=False)
             metadata_ = Column(metadata_dtype)
-            node_id = Column(VARCHAR)
+            node_id = Column(VARCHAR, unique=True)
             embedding = Column(Vector(embed_dim))  # type: ignore
 
         model = type(
@@ -398,7 +398,13 @@ def add(self, nodes: List[BaseNode], **add_kwargs: Any) -> List[str]:
         self._initialize()
         ids = []
         with self._session() as session, session.begin():
+            from sqlalchemy import delete
+
             for node in nodes:
+                stmt = delete(self._table_class).where(
+                    self._table_class.node_id == node.node_id
+                )
+                session.execute(stmt)
                 ids.append(node.node_id)
                 item = self._node_to_table_row(node)
                 session.add(item)