HOT update (heap-only tuple)

RU: HOT-обновление (heap-only tuple)

A PostgreSQL optimization that avoids writing a new index entry when an UPDATE does not change any indexed column and the new tuple fits on the same heap page. The old tuple's t_ctid pointer forms a HOT chain to the new version; VACUUM can later prune the chain without touching index pages, significantly reducing write amplification on frequently updated rows.