Hi,
On 21 Aug 2009, at 15:49, Jay Pipes wrote:
Alex Yurchenko wrote:
On Thu, 20 Aug 2009 12:36:42 -0400, Morgan Tocker
<[email protected]> wrote:
While I agree with the comments about CRCs being weak, they are
awesomely fast. And Nehalem CPUs make them even faster:
http://en.wikipedia.org/wiki/SSE4#SSE4.2
Well, according to http://www.cryptopp.com/benchmarks.html CRC32
might be
awesomely fast only on those Nehalem things. Otherwise it seems to be
pathetically slow (for a 32bit value).
General unsuitability for the task was already addressed in
previous posts.
Baron has chosen FNV hash not for naught.
The next argument is just which sane default should be chosen. In
which case, I'd be interested to let benchmarks speak.
All who responded to this thread:
Thank you! I'll be putting together a wiki page which summarizes
the viewpoints expressed and lays out (hopefully cleanly) a set of
options to either build into the server, the replication streaming,
both, or none :)
One final thing to add on this - I'm not sure what version you cloned
from, or how you are currently dealing with double/float values - but
they are something that you should take care with when running
CHECKSUM TABLE too, because whilst they may appear to show the same
values in any output that you get from the database, at their full
precision (as stored) they do not checksum the same at all in some
situations - I spent a good amount of time trying to debug the problem
for a customer:
http://bugs.mysql.com/bug.php?id=30041
It was fixed by using a different library, in 6.0.5..
Cheers,
Mark
--
Mark Leith
MySQL Regional Support Manager, Americas
Sun Microsystems, Inc., http://www.sun.com/mysql/
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