diff --git a/netbox/core/migrations/0025_add_job_execution_time.py b/netbox/core/migrations/0025_add_job_execution_time.py
index 049bc7ab2..f8c58d9ed 100644
--- a/netbox/core/migrations/0025_add_job_execution_time.py
+++ b/netbox/core/migrations/0025_add_job_execution_time.py
@@ -1,28 +1,4 @@
 from django.db import migrations, models
-from django.db.models import DurationField, ExpressionWrapper, F
-
-BATCH_SIZE = 5000
-
-
-def populate_execution_time(apps, schema_editor):
-    """
-    Populate execution_time for existing jobs which have both a start and completion time recorded.
-    Updates are performed in batches, as installations which retain job history indefinitely can
-    accumulate a very large number of rows.
-    """
-    Job = apps.get_model("core", "Job")
-    queryset = Job.objects.filter(started__isnull=False, completed__isnull=False)
-    execution_time = ExpressionWrapper(F("completed") - F("started"), output_field=DurationField())
-
-    last_pk = 0
-    while True:
-        pks = list(
-            queryset.filter(pk__gt=last_pk).order_by("pk").values_list("pk", flat=True)[:BATCH_SIZE]
-        )
-        if not pks:
-            break
-        Job.objects.filter(pk__in=pks).update(execution_time=execution_time)
-        last_pk = pks[-1]
 
 
 class Migration(migrations.Migration):
@@ -37,8 +13,4 @@ class Migration(migrations.Migration):
             name="execution_time",
             field=models.DurationField(blank=True, editable=False, null=True),
         ),
-        migrations.RunPython(
-            code=populate_execution_time,
-            reverse_code=migrations.RunPython.noop,
-        ),
     ]
diff --git a/netbox/core/migrations/0026_populate_job_execution_time.py b/netbox/core/migrations/0026_populate_job_execution_time.py
new file mode 100644
index 000000000..e74182024
--- /dev/null
+++ b/netbox/core/migrations/0026_populate_job_execution_time.py
@@ -0,0 +1,46 @@
+from django.db import migrations
+from django.db.models import DurationField, ExpressionWrapper, F
+
+BATCH_SIZE = 5000
+
+
+def populate_execution_time(apps, schema_editor):
+    """
+    Populate execution_time for existing jobs which have both a start and completion time recorded.
+    Updates are performed in batches, as installations which retain job history indefinitely can
+    accumulate a very large number of rows. Rows which already have a value are skipped, so that an
+    interrupted run can simply be resumed.
+    """
+    Job = apps.get_model("core", "Job")
+    queryset = Job.objects.filter(
+        started__isnull=False, completed__isnull=False, execution_time__isnull=True
+    )
+    execution_time = ExpressionWrapper(F("completed") - F("started"), output_field=DurationField())
+
+    last_pk = 0
+    while True:
+        pks = list(
+            queryset.filter(pk__gt=last_pk).order_by("pk").values_list("pk", flat=True)[:BATCH_SIZE]
+        )
+        if not pks:
+            break
+        Job.objects.filter(pk__in=pks).update(execution_time=execution_time)
+        last_pk = pks[-1]
+
+
+class Migration(migrations.Migration):
+    # The backfill is deliberately kept out of the migration which adds the column, so that the
+    # ACCESS EXCLUSIVE lock taken by ALTER TABLE is not held for its duration. Running without a
+    # wrapping transaction is what allows the batching above to bound the work actually held open.
+    atomic = False
+
+    dependencies = [
+        ("core", "0025_add_job_execution_time"),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            code=populate_execution_time,
+            reverse_code=migrations.RunPython.noop,
+        ),
+    ]