Re: [BeginnerQuestion]Why these is 6 rows in my SELECT statement?

On Thu, Sep 08, 2022 at 04:37:00PM +0800, BeginnerC wrote:
> Hello community,
> I am checking my pg_stat_activity view,but something confused me.
> Just like this:
> 
> postgres=# SELECT wait_event_type, wait_event FROM pg_stat_activity;
> wait_event_type |     wait_event
> -----------------+---------------------
> Activity        | AutoVacuumMain
> Activity        | LogicalLauncherMain
>                 |
> Activity        | BgWriterHibernate
> Activity        | CheckpointerMain
> Activity        | WalWriterMain
> (6 rows)
> 
> As you can see, the third row is empty,but I don't know why.
> Can anyone provide some solution to me?
> Thanks in advance!

Please do:

\pset null '-- null --'
SELECT wait_event_type, wait_event FROM pg_stat_activity;

it will most likely show -- null -- in these fields. which means values
in these columns are null.SELECT wait_event_type, wait_event FROM
pg_stat_activity;

You can find more about this/these backends by doing:

select * from pg_stat_activity where wait_event_type is null \gx

depesz