mnesia, large datasets and key range lookups

Jouni Rynö <>
Fri Jul 16 10:01:23 CEST 2004


On Sat, 2004-07-17 at 22:58 +0200, Ulf Wiger wrote:

> One advantage to having fragmentation support implemented in a callback
> module is that one doesn't have to bear the overhead of looking up
> fragmentation metadata when using the normal access functions This allows
> mnesia to be pretty lean and mean in its default functionality, and still
> be extensible for those who need that.
> 
ok, that makes sense.

> 
> > And while I'm whining about my lack of understanding, the bench-program
> > in the mnesia examples directory is supposed to use fragmented tables,
> > but it does not use those activity calls.
> 
> It does, but perhaps not for all accesses.
> If you look into bench_generate.erl, for example, you will find calls
> to mnesia:activity(), sometimes in the form of an
> rpc:call(mnesia,activity,...)
> 

Ah, so it does. What does not, is the mnesia_tpcb.erl (too many listings
around). The frag_add_delta makes direct calls to mnesia:read etc.

Jouni
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