Re: Checksums by default?

Magnus,

* Magnus Hagander (magnus(at)hagander(dot)net) wrote:
> On Sat, Jan 21, 2017 at 3:05 PM, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
> wrote:
>
> > On Sat, Jan 21, 2017 at 7:39 PM, Magnus Hagander <magnus(at)hagander(dot)net>
> > wrote:
> > > Is it time to enable checksums by default, and give initdb a switch to
> > turn
> > > it off instead?
> > >
> > > I keep running into situations where people haven't enabled it, because
> > (a)
> > > they didn't know about it, or (b) their packaging system ran initdb for
> > them
> > > so they didn't even know they could. And of course they usually figure
> > this
> > > out once the db has enough data and traffic that the only way to fix it
> > is
> > > to set up something like slony/bucardo/pglogical and a whole new server
> > to
> > > deal with it.. (Which is something that would also be good to fix -- but
> > > having the default changed would be useful as well)
> >
> > Perhaps that's not mandatory, but I think that one obstacle in
> > changing this default is to be able to have pg_upgrade work from a
> > checksum-disabled old instance to a checksum-enabled instance. That
> > would really help with its adoption.
>
> That's a different usecase though.

Agreed.

> If we just change the default, then we'd have to teach pg_upgrade to
> initialize the upgraded cluster without checksums. We still need to keep
> that *option*, just reverse the default.

Just to clarify- pg_upgrade doesn't init the new database, the user (or
a distribution script) does. As such *pg_upgradecluster* would have to
know to init the new cluster correctly based on the options the old
cluster was init'd with, but it might actually already do that (not sure
off-hand), and, even if it doesn't, it shouldn't be too hard to make it
to that.

> Being able to enable checksums on the fly is a different feature. Which I'd
> really like to have. I have some unfinished code for it, but it's a bit too
> unfinished so far :)

Agreed.

Thanks!

Stephen