bloat

Bloat is space the table holds but does not use: dead tuples not yet vacuumed, plus free space from tuples vacuumed long ago that inserts never refilled. Vacuum makes space reusable inside the file; it almost never shrinks the file itself, so a table that once bloated stays big until a rewrite. The steady-state bloat of a healthy table is roughly the dead rows that accumulate between two vacuum runs, which is why the trigger cadence, not vacuum speed, decides how fat a table runs.