$ pg_dump --help |grep "\--jobs"
  -j, --jobs=NUM               use this many parallel jobs to dump


$ pg_restore --help |grep "\--jobs"
  -j, --jobs=NUM               use this many parallel jobs to restore

$ vacuumdb --help |grep "\--jobs"
  -j, --jobs=NUM                  use this many concurrent connections to vacuum

postgres=# set force_parallel_mode=on;
SET


postgres=# explain (costs off,timing off,analyze on) select count(*) from test;
                                QUERY PLAN
--------------------------------------------------------------------------
 Finalize Aggregate (actual rows=1 loops=1)
   ->  Gather (actual rows=3 loops=1)
         Workers Planned: 2
         Workers Launched: 2
         ->  Partial Aggregate (actual rows=1 loops=3)
               ->  Parallel Seq Scan on test (actual rows=110187 loops=3)
 Planning Time: 0.046 ms
 Execution Time: 74.961 ms
(8 rows)

postgres=# set max_parallel_maintenance_workers =4;
SET

create index concurrently（不堵塞DML）

postgres=# set enable_parallel_hash = on;
SET

reindex concurrently（不堵塞DML）

postgres=# vacuum (freeze,verbose,parallel 2);

$ vacuumdb --help |grep "\--parallel"
  -P, --parallel=PARALLEL_DEGREE  use this many background workers for vacuum, if available

$ reindexdb --help |grep "\--jobs"
  -j, --jobs=NUM            use this many concurrent connections to reindex