Re: CRCs (was: beta testing version)

On Thu, Dec 07, 2000 at 12:22:12PM -0800, Mikheev, Vadim wrote:
> > > That's why an end marker must follow all valid records.
> ...
> >
> > That requires an extra out-of-sequence write.
>
> Yes, and also increase probability to corrupt already committed
> to log data.
>
> > (I'd also like to see CRCs on all the table blocks as well; is there
> > a place to put them?)
>
> Do we need it? "physical log" feature suggested by Andreas will protect
> us from non atomic data block writes.

There are myriad sources of corruption, including RAM bit rot and
software bugs. The earlier and more reliably it's caught, the better.
The goal is to be able to say that a power outage won't invisibly
corrupt your database.

Here is are sources to a 64-bit CRC computation, under BSD license:

http://gcc.gnu.org/ml/gcc/1999-11n/msg00592.html

Nathan Myers
ncm(at)zembu(dot)com