On Thu, Dec 07, 2000 at 07:36:33PM -0500, Tom Lane wrote:
> [EMAIL PROTECTED] (Nathan Myers) writes:
> > 2. I disagree with way the above statistics were computed. That eleven
> >million-year figure gets whittled down pretty quickly when you
> >factor in all the sources of corruption, e
On Fri, Dec 08, 2000 at 03:38:09PM -0500, Tom Lane wrote:
> Bruce Guenter <[EMAIL PROTECTED]> writes:
> > MD5 is a cryptographic hash, which means (AFAIK) that ideally it is
> > impossible to produce a collision using any other method than brute
> > force attempts.
> True but irrelevant. What we
Bruce Guenter <[EMAIL PROTECTED]> writes:
> MD5 is a cryptographic hash, which means (AFAIK) that ideally it is
> impossible to produce a collision using any other method than brute
> force attempts.
True but irrelevant. What we need to worry about is the probability
that a random error will be
Bruce Guenter <[EMAIL PROTECTED]> writes:
> ... Taking an
> arbitrary 32 bits of a MD5 would likely be less collision prone than
> using a 32-bit CRC, and it appears faster as well.
... but that would be an algorithm that you know NOTHING about the
properties of. What is your basis for asserting
On Fri, Dec 08, 2000 at 10:36:39AM -0800, Ian Lance Taylor wrote:
>Incidentally, I benchmarked the previously mentioned 64-bit fingerprint,
>the standard 32-bit CRC, MD5 and SHA, and the fastest algorithm on my
>Celeron and on a PIII was MD5. The 64-bit fingerprint was only a hair
>
On Fri, Dec 08, 2000 at 01:58:12PM -0500, Tom Lane wrote:
> Bruce Guenter <[EMAIL PROTECTED]> writes:
> > ... Taking an
> > arbitrary 32 bits of a MD5 would likely be less collision prone than
> > using a 32-bit CRC, and it appears faster as well.
>
> ... but that would be an algorithm that you k
Date: Fri, 8 Dec 2000 12:19:39 -0600
From: Bruce Guenter <[EMAIL PROTECTED]>
Incidentally, I benchmarked the previously mentioned 64-bit fingerprint,
the standard 32-bit CRC, MD5 and SHA, and the fastest algorithm on my
Celeron and on a PIII was MD5. The 64-bit fingerprint was onl
On Thu, Dec 07, 2000 at 04:01:23PM -0800, Nathan Myers wrote:
> 1. Computing a CRC-64 takes only about twice as long as a CRC-32, for
>2^32 times the confidence. That's pretty cheap confidence.
Incidentally, I benchmarked the previously mentioned 64-bit fingerprint,
the standard 32-bit CRC,
[EMAIL PROTECTED] (Nathan Myers) writes:
> 2. I disagree with way the above statistics were computed. That eleven
>million-year figure gets whittled down pretty quickly when you
>factor in all the sources of corruption, even without crashes.
>(Power failures are only one of many s
On Thu, Dec 07, 2000 at 04:35:00PM -0500, Tom Lane wrote:
> Remember that we are already sitting atop hardware that's really
> pretty reliable, despite the carping that's been going on in this
> thread. All that we have to do is detect the infrequent case where a
> block of data didn't get written
"Mikheev, Vadim" <[EMAIL PROTECTED]> writes:
>> I would strongly suggest to use strong hashes like RIPEMD or
>> MD5 instead of CRC-32 and the like.
> Other opinions? Also, we shouldn't forget licence issues.
I agree with whoever commented that crypto hashes are silly for this
application. A 64-
> > This may be implemented very fast (if someone points me where
> > I can find CRC func). And I could implement "physical log"
> > till next monday.
>
> I have been experimenting with CRCs for the past 6 month in
> our database for internal logging purposes. Downloaded a lot of
> hash librarie
On Thu, Dec 07, 2000 at 06:40:49PM +1100, Horst Herb wrote:
> > This may be implemented very fast (if someone points me where
> > I can find CRC func). And I could implement "physical log"
> > till next monday.
>
> As the logging might include large data blocks, especially now that
> we can TOAST
Horst Herb wrote:
>
> > This may be implemented very fast (if someone points me where
> > I can find CRC func). And I could implement "physical log"
> > till next monday.
>
> I have been experimenting with CRCs for the past 6 month in our database for
> internal logging purposes. Downloaded a lo
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