This order seems more natural.  It starts with details that are
particular to heap and index data structures, and ends with system-level
costs incurred during the autovacuum worker's VACUUM/ANALYZE operation.

Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WzkzxK6ahA9xxsOftRtBX_R0swuHZsvo4QUbak1Bz7hb7Q@mail.gmail.com
Backpatch: 14-, which enhanced the log output in various ways.