Database enum, lookup table or plain text

A lookup table with a foreign key, unless the set is genuinely fixed forever. Database enums require a migration to add a value and cannot carry attributes; plain text accepts typos silently and then you have three spellings of the same status in production.

At ten times the size the bottleneck moves from the operation itself to what it competes with: memory, locks and the people who have to run it. The approach stays, the batching gets smaller and the schedule matters more.