fix: stabilize backend services and frontend pointer

fastapi_modules/fastapi_leaudit/services/impl/ragChatServiceImpl.py

@@ -54,6 +54,8 @@ class RagChatServiceImpl(IRagChatService):
     _task_done: dict[str, bool] = {}
     _task_locks: dict[str, asyncio.Lock] = {}
     _title_tasks: dict[str, asyncio.Task] = {}
+    _chat_schema_checked = False
+    _chat_schema_lock = asyncio.Lock()
 
     def __init__(self) -> None:
         self.TenantResolver = TenantResolver()
@@ -731,8 +733,34 @@ class RagChatServiceImpl(IRagChatService):
         )
 
     async def _ensure_rag_chat_schema(self, session) -> None:
-        await session.execute(text("ALTER TABLE rag_chat_app ADD COLUMN IF NOT EXISTS tenant_code VARCHAR(64) NULL"))
-        await session.execute(text("CREATE INDEX IF NOT EXISTS idx_rag_chat_app_tenant_code ON rag_chat_app(tenant_code) WHERE deleted_at IS NULL"))
+        if self.__class__._chat_schema_checked:
+            return
+
+        async with self.__class__._chat_schema_lock:
+            if self.__class__._chat_schema_checked:
+                return
+
+            exists = (
+                await session.execute(
+                    text(
+                        """
+                        SELECT 1
+                        FROM information_schema.columns
+                        WHERE table_schema = current_schema()
+                          AND table_name = 'rag_chat_app'
+                          AND column_name = 'tenant_code'
+                        """
+                    )
+                )
+            ).scalar_one_or_none()
+            if exists:
+                self.__class__._chat_schema_checked = True
+                return
+
+            await session.execute(text("SET LOCAL lock_timeout = '1000ms'"))
+            await session.execute(text("ALTER TABLE rag_chat_app ADD COLUMN tenant_code VARCHAR(64) NULL"))
+            await session.execute(text("CREATE INDEX IF NOT EXISTS idx_rag_chat_app_tenant_code ON rag_chat_app(tenant_code) WHERE deleted_at IS NULL"))
+            self.__class__._chat_schema_checked = True
 
     @staticmethod
     def _tenant_context_is_global(tenant_context: dict[str, str | None]) -> bool: