fix:delete empty table bug (#15517)

Co-authored-by: huangzhuo <huangzhuo1@xiaomi.com>

api/core/rag/datasource/vdb/pgvector/pgvector.py

 import json
+import logging
 import uuid
 from contextlib import contextmanager
 from typing import Any
 
+import psycopg2.errors
 import psycopg2.extras  # type: ignore
 import psycopg2.pool  # type: ignore
 from pydantic import BaseModel, model_validator
         if not ids:
             return
         with self._get_cursor() as cur:
-            cur.execute(f"DELETE FROM {self.table_name} WHERE id IN %s", (tuple(ids),))
+            try:
+                cur.execute(f"DELETE FROM {self.table_name} WHERE id IN %s", (tuple(ids),))
+            except psycopg2.errors.UndefinedTable:
+                # table not exists
+                logging.warning(f"Table {self.table_name} not found, skipping delete operation.")
+                return
+            except Exception as e:
+                raise e
 
     def delete_by_metadata_field(self, key: str, value: str) -> None:
         with self._get_cursor() as cur: