A single NULL column silently broke two unrelated systems in the same database

A software team at nlqdb discovered that a NULL timestamp in their database registry's last_queried_at column caused two separate systems to fail simultaneously. A daily sweep meant to evict anonymous databases older than 90 days silently retained all records, while a funnel metric counting active databases always returned zero. The root cause was a migration that backfilled existing rows but never updated the INSERT path for newly created records, leaving all post-migration rows with a NULL value. Because SQL comparisons against NULL produce neither true nor false, both systems produced incorrect results without raising any obvious errors. The fix required just two changes: seeding the column at creation time and re-running the backfill once.