[erlang-questions] mnesia: composite keys?

Peter Sabaini <>
Fri Jan 9 22:45:03 CET 2009


Hello list,

I've read[1] that mnesia doesn't support composite keys. It seems I can use 
keys made up of tuples though:

()11> mnesia:create_table(test, [{attributes, [id, data]}]).
{atomic,ok}
()19> Ins = fun() -> mnesia:write({test, {a_key, 0}, "asdfasdf"}) 
end.
#Fun<erl_eval.20.67289768>
()20> mnesia:transaction(Ins).
{atomic,ok}
()21> R = fun() -> mnesia:read(test, {a_key, 0}) end.
#Fun<erl_eval.20.67289768>
()22> mnesia:transaction(R).
{atomic,[{test,{a_key,0},"asdfasdf"}]}


Is tuples as keys common practice or A Really Bad Idea(tm)?

thx,
peter.


[1] http://www.erlang.org/pipermail/erlang-questions/2008-February/032903.html
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