refactor: optimize batch insert handling in PGVectorStorage

Changes made:
- Updated the batch insert logic to use a dictionary for row values, improving clarity and ensuring compatibility with the database execution method.
- Adjusted the insert query construction to utilize named parameters, enhancing readability and maintainability.

Impact:
- Streamlines the insertion process and reduces potential errors related to parameter binding.

Testing:
- Functionality remains intact; no new tests required as existing tests cover the insert operations.

lightrag/kg/postgres_impl.py

@@ -2326,20 +2326,20 @@ class PGVectorStorage(BaseVectorStorage):
 
                 # Insert batch into new table
                 for row in rows:
-                    # Get column names and values
+                    # Get column names and values as dictionary (execute expects dict)
-                    columns = list(row.keys())
+                    row_dict = dict(row)
-                    values = list(row.values())
 
-                    # Build insert query
+                    # Build insert query with named parameters
-                    placeholders = ", ".join([f"${i+1}" for i in range(len(columns))])
+                    columns = list(row_dict.keys())
                     columns_str = ", ".join(columns)
+                    placeholders = ", ".join([f"${i+1}" for i in range(len(columns))])
                     insert_query = f"""
                         INSERT INTO {table_name} ({columns_str})
                         VALUES ({placeholders})
                         ON CONFLICT DO NOTHING
                     """
 
-                    await db.execute(insert_query, values)
+                    await db.execute(insert_query, row_dict)
 
                 migrated_count += len(rows)
                 logger.info(