Thread: min_wal_size > max_wal_size is accepted

Hello,

It is possible to startup an instance with min > max, without the system 
complaining:

mrechte=# show min_wal_size ;

2020-05-07 11:12:11.422 CEST [11098] LOG:  durée : 0.279 ms

  min_wal_size

--------------

  128MB

(1 ligne)



mrechte=# show max_wal_size ;

2020-05-07 11:12:12.814 CEST [11098] LOG:  durée : 0.275 ms

  max_wal_size

--------------

  64MB

(1 ligne)


This could be an issue ?

> Hi,
> 
> Le jeu. 7 mai 2020 à 11:13, Marc Rechté <marc4@rechte.fr 
> <mailto:marc4@rechte.fr>> a écrit :
> 
>     Hello,
> 
>     It is possible to startup an instance with min > max, without the
>     system
>     complaining:
> 
>     mrechte=# show min_wal_size ;
> 
>     2020-05-07 11:12:11.422 CEST [11098] LOG:  durée : 0.279 ms
> 
>        min_wal_size
> 
>     --------------
> 
>        128MB
> 
>     (1 ligne)
> 
> 
> 
>     mrechte=# show max_wal_size ;
> 
>     2020-05-07 11:12:12.814 CEST [11098] LOG:  durée : 0.275 ms
> 
>        max_wal_size
> 
>     --------------
> 
>        64MB
> 
>     (1 ligne)
> 
> 
>     This could be an issue ?
> 
> 
> I don't see how this could be an issue. You'll get a checkpoint every 
> time 64MB have been written before checkpoint_timeout kicked in. And WAL 
> files will be removed if you have more than 128MB of them.
> 
> Not the smartest configuration, but not a damaging one either.
> 
> 
> -- 
> Guillaume.

I have some doubts when I see such code in 
backend/access/transam/xlog.c:2334



    if (recycleSegNo < minSegNo)

        recycleSegNo = minSegNo;

    if (recycleSegNo > maxSegNo)

        recycleSegNo = maxSegNo;