backfill
A backfill populates or recomputes existing data after a rule or schema change.
Use this when A new field works for new records but is missing from historical ones.
without the term
“I added a new 'slug' column. New posts get one, but all the old posts are empty. Can you fill them in without locking up the database or messing up posts being edited right now?”
with the term · How do you ask a model for backfill?
Backfill this field in resumable batches. Test restart and concurrent edits, and verify live traffic stays within its performance budget.
What is backfill?
A job that fills in or recomputes a value for existing rows in small, resumable batches, while the live app keeps writing.
Why does backfill matter when vibe coding?
A single large update can block production traffic or restart from zero after failure.
How do you do backfill?
Process bounded ranges, persist progress, and define how concurrent writes interact with the job.
What goes wrong with backfill?
Overwriting a newer live value with a value computed from an older snapshot.