Re: Checksums by default?

On Sat, Jan 21, 2017 at 8:16 PM, Ants Aasma <ants(dot)aasma(at)eesti(dot)ee> wrote:

> On Sat, Jan 21, 2017 at 7:39 PM, Petr Jelinek
> <petr(dot)jelinek(at)2ndquadrant(dot)com> wrote:
> > So in summary "postgresql.conf options are easy to change" while "initdb
> > options are hard to change", I can see this argument used both for
> > enabling or disabling checksums by default. As I said I would be less
> > worried if it was easy to turn off, but we are not there afaik. And even
> > then I'd still want benchmark first.
>
> Adding support for disabling checksums is almost trivial as it only
> requires flipping a value in the control file. And I have somewhere
> sitting around a similarly simple tool for turning on checksums while
> the database is offline. FWIW, based on customers and fellow
> conference goers I have talked to most would gladly take the
> performance hit, but not the downtime to turn it on on an existing
> database.
>

This is exactly the scenario I've been exposed to over and over again. If
it can be turned on/off online, then the default matters a lot less. But it
has to be online.

Yes, you can set up a replica (which today requires third party products
like slony, bucardo or pglogical -- at least we'll hopefully have pglogical
fully in 10, but it's still a very expensive way to fix the problem).

If we can make it cheap and easy to turn them off, that makes a change of
the default a lot cheaper. Did you have a tool for that sitting around as
well?

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