On Wed, Apr 18, 2018 at 10:37 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: > On Fri, Apr 13, 2018 at 10:36 PM, Robert Haas <robertmh...@gmail.com> wrote: >> On Thu, Apr 12, 2018 at 9:29 PM, Michael Paquier <mich...@paquier.xyz> wrote: >>> Still does it matter when the change is effective? >> >> I don't really care deeply about when the change takes effect, but I >> do care about whether the time when the system *says* the change took >> effect is the same as when it *actually* took effect. If those aren't >> the same, it's confusing. >> > > So, what in your opinion is the way to deal with this? If we make it > a PGC_POSTMASTER parameter, it will have a very clear behavior and > users don't need to bother whether they have a risk of torn page > problem or not and as a side-impact the code will be simplified as > well. However, as Michael said the people who get the benefit of this > option by disabling/enabling this parameter might complain. Keeping > it as a SIGHUP option has the drawback that even after the user has > enabled it, there is a risk of torn pages.
I would just document the risks. If the documentation says that you can't rely on the value until after the next checkpoint, or whatever the rule is, then I think we're fine. I don't think that we really have the infrastructure to do any better; if we try, we'll just end up with odd warts. Documenting the current set of warts is less churn and less work. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
