perf: batch-load messages in advanced-chat workflow run list to remove N+1 (#38359)

Co-authored-by: Yunlu Wen <yunlu.wen@dify.ai>

api/services/workflow_run_service.py

@@ -2,7 +2,7 @@ import threading
 from collections.abc import Sequence
 from typing import TypedDict
 
-from sqlalchemy import Engine
+from sqlalchemy import Engine, select
 from sqlalchemy.orm import sessionmaker
 
 import contexts
@@ -12,6 +12,7 @@ from models import (
     Account,
     App,
     EndUser,
+    Message,
     WorkflowNodeExecutionModel,
     WorkflowRun,
     WorkflowRunTriggeredFrom,
@@ -72,9 +73,29 @@ class WorkflowRunService:
 
         pagination = self.get_paginate_workflow_runs(app_model, args, triggered_from)
 
+        # Batch-load the associated Message for every run in a single query to avoid
+        # an N+1 pattern: the deprecated WorkflowRun.message property issues one query
+        # per run. The filter matches that property exactly (app_id + workflow_run_id).
+        workflow_runs = pagination.data
+        run_ids = [workflow_run.id for workflow_run in workflow_runs]
+        messages_by_run_id: dict[str, Message] = {}
+        if run_ids:
+            messages = db.session.scalars(
+                select(Message).where(
+                    Message.app_id == app_model.id,
+                    Message.workflow_run_id.in_(run_ids),
+                )
+            ).all()
+            for loaded_message in messages:
+                run_id = loaded_message.workflow_run_id
+                if run_id is None:
+                    continue
+                # setdefault mirrors scalar()'s single-row-per-run semantics.
+                messages_by_run_id.setdefault(run_id, loaded_message)
+
         with_message_workflow_runs = []
-        for workflow_run in pagination.data:
-            message = workflow_run.message
+        for workflow_run in workflow_runs:
+            message = messages_by_run_id.get(workflow_run.id)
             with_message_workflow_run = WorkflowWithMessage(workflow_run=workflow_run)
             if message:
                 with_message_workflow_run.message_id = message.id