Re: Online enabling of checksums

On Mon, Mar 26, 2018 at 10:09 PM, Tomas Vondra <tomas.vondra@2ndquadrant.com
> wrote:

> Hi,
>
> I see enable_data_checksums() does this:
>
>     if (cost_limit <= 0)
>         ereport(ERROR,
>                 (errmsg("cost limit must be a positive value")));
>
> Is there a reason not to allow -1 (no limit), just like for vacuum_cost?
>
>
Eh. vaccum_cost_limit cannot be set to -1 (1 is the lowest). Neither can
vacuum_cost_delay -- it is set to *0* to disable it (which is how the
cost_delay parameter is handled here as well).

Are you thinking autovacuum_vacuum_cost_limit where -1 means "use
vacuum_cost_limit"?

The reason to disallow cost_limit=0 is to avoid divide-by-zero. We could
allow -1 and have it mean "use vacuum_cost_limit", but I'm not sure how
relevant that really would be in this context?

-- 
 Magnus Hagander
 Me: https://www.hagander.net/ <http://www.hagander.net/>
 Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>