Florian Weimer <[EMAIL PROTECTED]> writes: > * Tom Lane: >> There's a lot of math behind CRCs but AFAIR Adler's method is pretty >> much ad-hoc.
> Correct me if I'm wrong, but the main reason for the WAL CRC is to > detect partial WAL writes (due to improper caching, for instance). Well, that's *a* reason, but not the only one, and IMHO not one that gives any particular guidance on what kind of checksum to use. > This means that you're out of the realm of traditional CRC analysis > anyway, because the things you are guarding against are neither burts > errors nor n-bit errors (for small n). I think short burst errors are fairly likely: the kind of scenario I'm worried about is a wild store corrupting a word of a WAL entry while it's waiting around to be written in the WAL buffers. So the CRC math does give me some comfort that that'll be detected. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings