discussion: mnesia table-specific options

Ulf Wiger <>
Mon Dec 20 14:56:11 CET 2010


Given that there are now several interesting performance options
for ets, and a 64-bit dets version is (sort of) in the works, it seems
a good time to consider how these things can be reflected in 
mnesia table definitions.

Some time ago, I introduced an 'external_copies' type in mnesia,
and this was used (with some modifications) by mnesiaex to provide
a TokyoCabinet back-end to mnesia. Thesis projects at Klarna have
played around with CouchDB backends etc.

I think that conceptually, it would seem good to keep the 
ram_copies, disc_copies and disc_only_copies, regardless of 
back-end, since they address higher-level access characteristics
(e.g. TokyoCabinet is, strictly speaking, also disc_only.)

A form of behaviour option could then be added that gives 
additional options - e.g. tuning parameters to InnoDB, dets, ets, 
or whatever back-end is being used.

Taking it one step further, it should be possible to specify a 
default behaviour for each copy type, and override per-table.

Comments?

BR,
Ulf W

Ulf Wiger, CTO, Erlang Solutions, Ltd.
http://erlang-solutions.com





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