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Rémy Coutable
26b9577719
Fix pagination on sorts with lots of ties ## What does this MR do? Fixes #18915. As we only order by the sorted column, we don't have any tie-breaker. Some orderings, like priority and weight, have lots of ties, so you can see duplicate results as you page through. (Timestamp columns are less susceptible to this.) ## Are there points in the code the reviewer needs to double check? I just picked `id DESC`, this could as easily be `id ASC`. ## Why was this MR needed? Postgres and MySQL don't guarantee that pagination with `LIMIT` and `OFFSET` will work as expected if the ordering isn't unique. From the Postgres docs: > When using `LIMIT`, it is important to use an `ORDER BY` clause that > constrains the result rows into a unique order. Otherwise you will get > an unpredictable subset of the query's rows Before: [1] pry(main)> issues = 1.upto(Issue.count).map { |i| Issue.sort('priority').page(i).per(1).map(&:id) }.flatten [2] pry(main)> issues.count => 81 [3] pry(main)> issues.uniq.count => 42 After: [1] pry(main)> issues = 1.upto(Issue.count).map { |i| Issue.sort('priority').page(i).per(1).map(&:id) }.flatten [2] pry(main)> issues.count => 81 [3] pry(main)> issues.uniq.count => 81 See merge request !4878