On Thu, 12 Mar 2020 at 19:50, Masahiko Sawada
<masahiko.sawada@2ndquadrant.com> wrote:
> The reason why you want to add new GUC parameters is to use different
> default values for insert-update table case and insert-only table
> case?
Yes, but in particular so it can be completely disabled easily.
> I think I understand the pros and cons of adding separate
> parameters, but I still cannot understand use cases where we cannot
> handle without separate parameters.
That's a lot of negatives. I think I understand that you don't feel
that additional GUCs are worth it?
Laurenz highlighted a seemingly very valid reason that the current
GUCs cannot be reused. Namely, say the table has 1 billion rows, if we
use the current scale factor of 0.2, then we'll run an insert-only
vacuum every 200 million rows. If those INSERTs are one per
transaction then the new feature does nothing as the wraparound vacuum
will run instead. Since this feature was born due to large insert-only
tables, this concern seems very valid to me.