Re: allowing wal_level change at run time

On 18 August 2015 at 18:46, Andres Freund <andres(at)anarazel(dot)de> wrote:

> ISTM that it's not too hard to
> a) make archive_mode PGC_SIGHUP
> b) make wal_level PGC_SIGHUP
>

+1

> c) automatically increase wal_level to logical whenever a logical
> replication slot is defined
>

-1

It would be easier to just have wal_level = logical always, but allow it to
be set lower if desired.

Increasing wal_level dynamically might otherwise happen too late.

> it seems considerably harder to
>
> d) make max_wal_senders PGC_SIGHUP
> e) make max_replication_slots PGC_SIGHUP
>
> because they need shmem, locks, and everything.
>
>
> Therefore I propose something slightly different:
>
> We change the default of max_wal_senders, max_replication_slots, to some
> reasonably high setting

Agreed, I suggest 8 as the default for each.

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