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fix(perf): Avoid extra queries in MonitorEnvironmentSerializer #106428

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Merged
kcons merged 1 commit into from
Jan 20, 2026
Merged

fix(perf): Avoid extra queries in MonitorEnvironmentSerializer #106428

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27 changes: 26 additions & 1 deletion src/sentry/monitors/serializers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -109,10 +109,29 @@ def get_attrs(
)
}

# Build date_added mapping, starting with cached monitors
date_added_by_monitor_id = {}
uncached_monitor_ids = set[int]()

for monitor_env in item_list:
if monitor_env.is_field_cached("monitor"):
# Extract date_added from cached monitor
date_added_by_monitor_id[monitor_env.monitor_id] = monitor_env.monitor.date_added
else:
# Need to fetch this monitor
uncached_monitor_ids.add(monitor_env.monitor_id)

# Batch query for uncached monitors - only fetch date_added field
if uncached_monitor_ids:
date_added_by_monitor_id.update(
Monitor.objects.filter(id__in=uncached_monitor_ids).values_list("id", "date_added")
)
Comment on lines +112 to +128
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@wedamija wedamija Jan 16, 2026

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Nit: No need to change if you don't want to , but a simple way to do this is prefetch_related_objects like

sentry/src/sentry/api/serializers/models/group.py

Line 239 in 86556c7

prefetch_related_objects(item_list, "project__organization")

The way you're doing it is more efficient since we bring down fewer fields, but this way is more concise.


return {
monitor_env: {
"environment": environments.get(monitor_env.environment_id),
"active_incident": serialized_incidents.get(monitor_env.id),
"date_added": date_added_by_monitor_id[monitor_env.monitor_id],
}
for monitor_env in item_list
}
Expand All @@ -123,7 +142,7 @@ def serialize(self, obj, attrs, user, **kwargs) -> MonitorEnvironmentSerializerR
"name": environment.name if environment else "[removed]",
"status": obj.get_status_display(),
"isMuted": obj.is_muted,
"dateCreated": obj.monitor.date_added,
"dateCreated": attrs["date_added"],
"lastCheckIn": obj.last_checkin,
"nextCheckIn": obj.next_checkin,
"nextCheckInLatest": obj.next_checkin_latest,
Expand Down Expand Up @@ -239,6 +258,12 @@ def get_attrs(self, item_list, user, **kwargs):
)

monitor_environments = list(monitor_environments_qs)

# Pre-cache monitors on the environments to avoid queries in MonitorEnvironmentSerializer
monitors_by_id = {monitor.id: monitor for monitor in item_list}
for monitor_env in monitor_environments:
monitor_env.set_cached_field_value("monitor", monitors_by_id[monitor_env.monitor_id])

serialized_monitor_environments = defaultdict(list)

for monitor_env, serialized in zip(
Expand Down
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