Today I’m very excited to announce the release of Oban v1.0.0-rc.1. This release has been a long time coming and it packs a lot of new features, performance improvements, stability fixes and updated defaults for pruning and heartbeats. If there aren’t any regressions or breaking changes then I’ll release 1.0.0 in one week.
This release does require a migration, but I crammed as many features as I could into it: priority jobs, tags, a discarded_at timestamp and a massively improved notifications trigger.
Thanks to everybody that contributed and reported issues. 
From the CHANGELOG:
Migration Required (V8)
This is the first required migration since 0.8.0, released in 09/2019. It brings with it a new column, discarded_at, a streamlined notifications trigger, job prioritiy and job tags.
Added
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[Oban] Add timezone support for scheduling cronjobs using timezones other than “Etc/UTC”. Using a custom timezone requires a timezone database such as tzdata.
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[Oban] Add dispatch_cooldown option to configure the minimum time between a producer fetching more jobs to execute.
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[Oban] Add beats_maxage option to configure how long heartbeat rows are retained in the oban_beats table. Each queue generates one row per second, so rows may accumulate quickly. The default value is now five minutes, down from one hour previously.
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[Oban.Job] Add discarded_at timestamp to help identify jobs that were discarded and not completed. The timestamp is added by the V8 migration and it is also included in the original create table from V1 as a minor space saving optimization (packing datetime columns together because they use a predictable 4bytes of space).
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[Oban.Job] Add numerical priority value to control the order of execution for jobs within a queue. The priority can be set between 0 and 3, with 0 being the default and the highest priority.
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[Oban.Job] Add tags field for arbitrarily organizing associated tags. Tags are a list of strings stored as an array in the database, making them easy to search and filter by.
Changed
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[Oban] Change the default prune value from :disabled to {:maxlen, 1_000}. Many people don’t change the default until they realize that a lot of jobs are lingering in the database. It is rare that anybody would want to keep all of their jobs forever, so a conservative default is better than :disabled.
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[Oban] Change oban_beats retention from one hour to five minutes. The value is now configurable, with a default of 300s. The lower bound is 60s because we require one minute of heartbeat activity to rescue orphaned jobs.
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[Oban.Queue.Producer] Introduce “dispatch cooldown” as a way to debounce repeatedly fetching new jobs. Repeated fetching floods the producer’s message queue and forces the producer to repeatedly fetch one job at a time, which is not especially efficient. Debounced fetching is much more efficient for the producer and the database, increasing maximum jobs/sec throughput so that it scales linearly with a queue’s concurrency settings (up to what the database can handle).
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[Oban.Query] Discard jobs that have exhausted the maximum attempts rather than rescuing them. This prevents repeatedly attempting a job that has consistently crashed the BEAM.
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[Oban.Query] Use transactional locks to prevent duplicate inserts without relying on unique constraints in the database. This provides strong unique guarantees without requiring migrations.
Removed
- [Oban.Notifications] An overhauled and simplified insert trigger no longer emits
update notifications. This was largely an internal implementation detail and wasn’t publicly documented, but it does effect the UI.
