mirror of
https://github.com/discourse/discourse.git
synced 2025-03-01 00:27:58 +08:00
ded6aed15e
This is a backport of 84e13e9.
We caught it in logs, race condition led to this error:
ActiveRecord::RecordNotUnique
(PG::UniqueViolation: ERROR: duplicate key value violates unique constraint "user_statuses_pkey"
DETAIL: Key (user_id)=(15) already exists.)
The reason the problem happened was that we were checking if a user has status and if not inserting status:
if user_status
...
else
self.user_status = UserStatus.create!(status)
end
The problem is that it's possible that another request will insert status just after we check if status exists and just before our request call `UserStatus.create!(status)`. Using `upsert` fixes the problem because under the hood `upsert` generates the only SQL request that uses "INSERT ... ON CONFLICT DO UPDATE". So we do everything in one SQL query, and that query takes care of resolving possible conflicts.