From 0c2fd9cacb840a75674c2d9b6664074a1d4e7221 Mon Sep 17 00:00:00 2001
From: LakshmiSravyaVedantham
 <38032391+LakshmiSravyaVedantham@users.noreply.github.com>
Date: Wed, 25 Feb 2026 12:14:21 -0800
Subject: [PATCH 1/2] perf: use load_only() in
 eager_load_dag_run_for_validation to reduce data fetched
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The get_dag_runs API endpoint was slow on large deployments because
eager_load_dag_run_for_validation() used selectinload on task_instances and
task_instances_histories without restricting which columns were fetched.
This caused SQLAlchemy to load all heavyweight columns (executor_config with
pickled data, hostname, rendered fields, etc.) for every task instance across
every DAG run in the result page — even though only dag_version_id is needed
to traverse the association proxy to DagVersion.

Add load_only(TaskInstance.dag_version_id) and
load_only(TaskInstanceHistory.dag_version_id) to the selectinload chains so
the SELECT for task instances fetches only the identity columns and the FK
needed to resolve the dag_version relationship, significantly reducing the
volume of data transferred from the database on busy deployments.

Fixes #62025
---
 .../src/airflow/api_fastapi/common/db/dag_runs.py  | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/airflow-core/src/airflow/api_fastapi/common/db/dag_runs.py b/airflow-core/src/airflow/api_fastapi/common/db/dag_runs.py
index 4eb586c851b77..2970551183b12 100644
--- a/airflow-core/src/airflow/api_fastapi/common/db/dag_runs.py
+++ b/airflow-core/src/airflow/api_fastapi/common/db/dag_runs.py
@@ -18,7 +18,7 @@
 from __future__ import annotations
 
 from sqlalchemy import func, select
-from sqlalchemy.orm import joinedload, selectinload
+from sqlalchemy.orm import joinedload, load_only, selectinload
 from sqlalchemy.orm.interfaces import LoaderOption
 
 from airflow.models.dag import DagModel
@@ -41,13 +41,23 @@
 
 
 def eager_load_dag_run_for_validation() -> tuple[LoaderOption, ...]:
-    """Construct the eager loading options necessary for a DagRunResponse object."""
+    """Construct the eager loading options necessary for a DagRunResponse object.
+
+    For the list endpoint (get_dag_runs), loading all task instance columns is
+    wasteful because we only need the dag_version_id FK to traverse to DagVersion.
+    Using load_only() on TaskInstance and TaskInstanceHistory restricts the SELECT
+    to just the identity columns and dag_version_id, avoiding large intermediate
+    result sets caused by loading heavyweight columns (executor_config, etc.) for
+    every task instance across every DAG run returned by the query.
+    """
     return (
         joinedload(DagRun.dag_model),
         selectinload(DagRun.task_instances)
+        .load_only(TaskInstance.dag_version_id)
         .joinedload(TaskInstance.dag_version)
         .joinedload(DagVersion.bundle),
         selectinload(DagRun.task_instances_histories)
+        .load_only(TaskInstanceHistory.dag_version_id)
         .joinedload(TaskInstanceHistory.dag_version)
         .joinedload(DagVersion.bundle),
         joinedload(DagRun.dag_run_note),

From 088df3cb9de81493c2ddfcda5a0b75e359982771 Mon Sep 17 00:00:00 2001
From: pierrejeambrun <pierrejbrun@gmail.com>
Date: Fri, 6 Mar 2026 11:40:48 +0100
Subject: [PATCH 2/2] Fix static checks

---
 airflow-core/src/airflow/api_fastapi/common/db/dag_runs.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/airflow-core/src/airflow/api_fastapi/common/db/dag_runs.py b/airflow-core/src/airflow/api_fastapi/common/db/dag_runs.py
index 2970551183b12..750a4ae61aa68 100644
--- a/airflow-core/src/airflow/api_fastapi/common/db/dag_runs.py
+++ b/airflow-core/src/airflow/api_fastapi/common/db/dag_runs.py
@@ -18,7 +18,7 @@
 from __future__ import annotations
 
 from sqlalchemy import func, select
-from sqlalchemy.orm import joinedload, load_only, selectinload
+from sqlalchemy.orm import joinedload, selectinload
 from sqlalchemy.orm.interfaces import LoaderOption
 
 from airflow.models.dag import DagModel
@@ -41,7 +41,8 @@
 
 
 def eager_load_dag_run_for_validation() -> tuple[LoaderOption, ...]:
-    """Construct the eager loading options necessary for a DagRunResponse object.
+    """
+    Construct the eager loading options necessary for a DagRunResponse object.
 
     For the list endpoint (get_dag_runs), loading all task instance columns is
     wasteful because we only need the dag_version_id FK to traverse to DagVersion.