[erlang-questions] MySQL cluster - MnesiaXXL

Scott Lystig Fritchie <>
Thu Oct 26 06:34:11 CEST 2006


>>>>> "pe" == Pat e <> writes:

pe> Also for example if we wanted to have Mnesia RAM-only serving (if
pe> it can serve tables on 128GB RAM machine - [...]

Having 16GB machines at my disposal, Mnesia works quite well.  I'd
hope that something 8x larger would behave just as well.

Memcached in Erlang is pretty easy to do: ets gets you most of the way
there.  I've done exactly a memcached-like thing in Erlang + Mnesia,
except for a few different, proprietary tweaks ... and having
different availability requirements (which makes life more complicated
than memcached's niche).

My app isn't as fast as memcached, but then again, my app is so much
faster than its requirements that I haven't bothered optimizing that
part of the app.  Several thousand updates/sec in Mnesia-replicated
tables is good enough for now.  :-) Mnesia does a lot of extra stuff
that memcached doesn't, so apples vs. apples comparisons aren't easy.

Re-implementing the memcached protocol in Erlang would be a short
exercise.  A good learning project for novices?  The protocol is
short, it does something useful, and you don't have write your own
client code for testing the server ... unless you want to write both.

-Scott



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