I use Memcache to cache results of MySQL queries. I've found that using
an MD5 hash of the SQL statement works well as the key. I don't know
the probability of issues where two different sets of data will produce
the same MD5. If you find that out please post to the list.
As far as speed goes, the time to perform an MD5 hash is negligible
compared to time to hit MySQL vs Memcache. Of course, my SQL statements
are relatively short in length.
An MD5 hash also has the added benefit of the short key length which I
can only assume allows you to cram more data into a smaller allocation
of RAM.
- John
Venkatesh KS wrote:
folks,
memcached supports variable length keys. But I am just curious as to
why not use md5 instead of lengthy keys. The keylen requirements for
my cache (which is very similar to squid proxy) is very high and I am
planning on using md5. I will read up to find out about the false
positive probability. But going md5 way will certainly cap the keylen
to 16bytes.
regards,
-venkatesh
