Re: Cost of XLogInsert CRC calculations

Tom Lane wrote:
> "Mark Cave-Ayland"  writes:
> 
>>Wow, a 64-bit CRC does seem excessive, especially when going back to Zmodem
>>days where a 50-100k file seemed to be easily protected by a 32-bit CRC. I'm
>>sure there are some error rates somewhere dependent upon the polynomial and
>>the types of error detected.... Try the following link towards the bottom:
>>http://www.ee.unb.ca/tervo/ee4253/crc.htm for some theory on detection rates
>>vs. CRC size.
> 
> 
> When the CRC size was decided, I recall someone arguing that it would
> really make a difference to have 1-in-2^64 chance of failure rather than
> 1-in-2^32.  I was dubious about this at the time, but didn't have any
> evidence showing that we shouldn't go for 64.  I suppose we ought to try
> the same example with a 32-bit CRC and see how much it helps.

Continuing this why not a 16-bit then ?


Regards
Gaetano Mendola