Tracking vaccum progress

For many years, people have asked for a progress tracker for vacuum. Finally, PostgreSQL 9.6 makes this wish come true by introducing a new system view. Here is how it works:

postgres=# SELECT * FROM pg_stat_progress_vacuum ?

-[ RECORD 1 ]------+--------------

pid | 29546
datid | 67535
datname | test
relid | 16402
phase | scanning heap
heap_blks_total | 6827
heap_blks_scanned | 77
heap_blks_vacuumed | 0
index_vacuum_count | 0
max_dead_tuples | 154
num_dead_tuples | 0

PostgreSQL will provide detailed information about ongoing vacuum processes so that people can track the progress of this vital operation.