test=# SELECT pg_stat_get_activity(NULL);
                                                   pg_stat_get_activity
--------------------------------------------------------------------------------------------------------------------------------
 (,4924,,"",,"",Activity,AutoVacuumMain,,,"2022-06-08 15:29:27.855337+08",,,,,,,"autovacuum launcher",f,,,,,,,,f,,f,1,0,unknown)
 (,4922,,"",,"",Activity,BgWriterMain,,,"2022-06-08 15:29:27.853938+08",,,,,,,"background writer",f,,,,,,,,f,,f,-1,0,unknown)
 (,4921,,"",,"",Activity,CheckpointerMain,,,"2022-06-08 15:29:27.852975+08",,,,,,,checkpointer,f,,,,,,,,f,,f,-1,0,unknown)
 (,4923,,"",,"",Activity,WalWriterMain,,,"2022-06-08 15:29:27.854843+08",,,,,,,walwriter,f,,,,,,,,f,,f,-1,0,unknown)
 (4 rows)