Alert about detecting unindexed "deleted_at" columns check

[rience]

Hi,

Recently I was investigating why some of our report generations take a long time. We use soft deletion in some tables with discard gem.

We iterate over bunch of records and we suffer from N+1 queries (but that's different problem). However, when loading associated records - Active Record does not add where discarded_at is NULL to WHERE clause. And because of that - index on foreign key column is not used. These indexes have condition - suggested by Active Record Doctor - where discarded_at is NULL. So in the end - table was full scanned.

What do you think about - either disabling that check or at least adding some info about that to documentation?