fix(perf): Avoid extra queries in MonitorEnvironmentSerializer#106428
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fix(perf): Avoid extra queries in MonitorEnvironmentSerializer#106428
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wedamija
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| # Build date_added mapping, starting with cached monitors | ||
| date_added_by_monitor_id = {} | ||
| uncached_monitor_ids = set[int]() | ||
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| 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) | ||
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| # 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") | ||
| ) |
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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
The way you're doing it is more efficient since we bring down fewer fields, but this way is more concise.
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MonitorEnvironmentSerializer relies on Monitor data, but fetching it via implicit query results in lots of unnecessary queries.
We can avoid this by batch fetching when it isn't cached, and using the cached value when available.
By ensuring the Monitor is cached in MonitorSerializer, where we already have the Monitors, no queries are required.