Some new mnesia benchmarking results

Chandrashekhar Mullaparthi Chandrashekhar.Mullaparthi@REDACTED
Fri Nov 9 15:43:58 CET 2001

> -----Original Message-----
> From: Ulf Wiger [mailto:etxuwig@REDACTED]
> Sent: 9 November 2001 14:28
> To: Per Bergqvist
> Cc: Sean Hinde; 'Erlang Questions'
> Subject: Re: Some new mnesia benchmarking results

> What are your access patterns like?
> I have some ideas that I'm testing currently.
> 1. Dan and Håkan have written a module in mnesia called
>    mnesia_frag.erl. It's wholly undocumented, except for the
>    source, but it seems to work really well. The idea is that
>    you can treat a number of regular mnesia tables as fragments
>    of a larger table. Operations on the "base table" access
>    the appropriate fragment based on a hashing function on
>    the key. Fragments are distributed evenly across a pool
>    of processors.

It is quite well documented in the mnesia user guide. We use it quite
extensively. The recent presentation by Sean in EUC'01 was about an
application which, among other things, every hour traverses the entire table
and marks some records for deletion. The way it is done is to traverse each
fragment independently. Saves our application from being unable to access
mnesia for too long. At any one time during the traversal there is a lock on
only one fragment.


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