[#148409] Reduce number of DB queries on Facility timeline page

[vandrijevik]

Release Notes

Reduce number of DB queries on Facility timeline page

Additional Context

Removes a few low-hanging N+1 fruits in the partials that we render for each instrument on the Facility’s timeline page, and reduces the typical number of queries per instrument from 10:

Before

Instrument Load (0.2ms)  SELECT `products`.* FROM `products` WHERE `products`.`type` IN ('Instrument') AND `products`.`schedule_id` = 2 AND `products`.`is_archived` = 0
 (0.3ms)  SELECT COUNT(*) FROM `reservations` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`type` IN ('OfflineReservation') AND `reservations`.`product_id` = 5 AND `reservations`.`reserve_end_at` IS NULL AND (reserve_start_at < '2019-03-14 21:04:48.751912')
InstrumentAlert Load (0.2ms)  SELECT  `instrument_alerts`.* FROM `instrument_alerts` WHERE `instrument_alerts`.`instrument_id` = 5 LIMIT 1
Reservation Load (0.9ms)  SELECT `reservations`.* FROM `reservations` INNER JOIN `order_details` ON `order_details`.`id` = `reservations`.`order_detail_id` INNER JOIN `orders` ON `orders`.`id` = `order_details`.`order_id` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`product_id` = 5 AND `orders`.`state` = 'purchased' AND (reserve_end_at >= '2019-03-14 05:00:00') AND (reserve_start_at < '2019-03-15 04:59:59.999999') ORDER BY `reservations`.`reserve_start_at` ASC
AdminReservation Load (0.2ms)  SELECT `reservations`.* FROM `reservations` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`type` IN ('AdminReservation') AND `reservations`.`product_id` = 5 AND (reserve_end_at >= '2019-03-14 05:00:00') AND (reserve_start_at < '2019-03-15 04:59:59.999999')
OfflineReservation Load (0.2ms)  SELECT `reservations`.* FROM `reservations` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`type` IN ('OfflineReservation') AND `reservations`.`product_id` = 5 AND (reserve_end_at >= '2019-03-14 05:00:00') AND (reserve_start_at < '2019-03-15 04:59:59.999999')
ScheduleRule Load (0.1ms)  SELECT `schedule_rules`.* FROM `schedule_rules` WHERE `schedule_rules`.`product_id` = 5
Relay Load (0.3ms)  SELECT  `relays`.* FROM `relays` WHERE `relays`.`instrument_id` = 5 LIMIT 1
 (0.2ms)  SELECT COUNT(*) FROM `reservations` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`type` IN ('OfflineReservation') AND `reservations`.`product_id` = 5 AND `reservations`.`reserve_end_at` IS NULL AND (reserve_start_at < '2019-03-14 21:04:48.767382')
 (0.4ms)  SELECT COUNT(*) FROM `reservations` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`type` IN ('OfflineReservation') AND `reservations`.`product_id` = 5 AND `reservations`.`reserve_end_at` IS NULL AND (reserve_start_at < '2019-03-14 21:04:48.768619')

to 5:

After

  OfflineReservation Load (0.4ms)  SELECT `reservations`.* FROM `reservations` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`type` IN ('OfflineReservation') AND `reservations`.`product_id` = 8 AND `reservations`.`type` IN ('OfflineReservation') AND `reservations`.`reserve_end_at` IS NULL AND (reserve_start_at < '2019-03-14 21:01:56.731311')
  Reservation Load (0.5ms)  SELECT `reservations`.* FROM `reservations` INNER JOIN `order_details` ON `order_details`.`id` = `reservations`.`order_detail_id` INNER JOIN `orders` ON `orders`.`id` = `order_details`.`order_id` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`product_id` = 8 AND `orders`.`state` = 'purchased' AND (reserve_end_at >= '2019-03-14 05:00:00') AND (reserve_start_at < '2019-03-15 04:59:59.999999') ORDER BY `reservations`.`reserve_start_at` ASC
  AdminReservation Load (0.3ms)  SELECT `reservations`.* FROM `reservations` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`type` IN ('AdminReservation') AND `reservations`.`product_id` = 8 AND (reserve_end_at >= '2019-03-14 05:00:00') AND (reserve_start_at < '2019-03-15 04:59:59.999999')
  OfflineReservation Load (0.2ms)  SELECT `reservations`.* FROM `reservations` WHERE `reservations`.`deleted_at` IS NULL AND `reservations`.`type` IN ('OfflineReservation') AND `reservations`.`product_id` = 8 AND (reserve_end_at >= '2019-03-14 05:00:00') AND (reserve_start_at < '2019-03-15 04:59:59.999999')
  ScheduleRule Load (0.1ms)  SELECT `schedule_rules`.* FROM `schedule_rules` WHERE `schedule_rules`.`product_id` = 8

Unfortunately, the remaining N+1 queries that we have (for an instrument’s reservations) are not trivial to remove because they depend on the selected date, so they can’t be preloaded. If this PR is not enough of a performance boost for the facility timeline page, we can at least try to combine the queries which load reservations for an instrument into one (instead of 5 per instrument).