Re: How much do the hint bits help?

On Wed, Dec 22, 2010 at 04:00:30PM +0000, Simon Riggs wrote:
> On Wed, 2010-12-22 at 17:42 +0200, Heikki Linnakangas wrote:
> > On 22.12.2010 17:31, Simon Riggs wrote:
> > > On Wed, 2010-12-22 at 17:01 +0200, Heikki Linnakangas wrote:
> > >> There's plenty of stuff in memory that's not covered by an
> > >> application-level CRC. That's what ECC RAM is for.
> > >
> > > http://www.google.com/research/pubs/archive/35162.pdf
> > >
> > > Google research shows that each DIMM has an 8% chance per annum of
> > > uncorrectable memory errors, even on ECC.
> >
> > You misread that paper. From summary:
>
> I read the paper in detail before I posted. If you think that finding an
> error in my quote disproves anything, you should read the whole paper. I
> see this:
>
> Conclusion 1
> "... Nonetheless, the remaining incidence of 0.22% per DIMM
> per year makes a crash-tolerant application layer indispens-
> able for large-scale server farms."
>
> What you are arguing for is a protection system that will reduce in
> effectiveness as we add more cache.
>
> What I am arguing in favour of is an option to allow people to protect
> their data, whatever the size of their cache. I'm not forcing you or
> anyone to use it, but I think its an important option to be offering to
> our users.

For what version of PostgreSQL are you proposing that we provide this
protection? Let's assume that it's before 10.0 so we can get some
idea of how this will arise :)

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
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