[erlang-questions] Mnesia, disk_log and dets

Ulf Wiger <>
Wed Feb 17 07:39:48 CET 2010

wde wrote:
> hello,
> I'm reading the source code of Mnesia to understand how things work
> :+) If I have understood correctly, for "disc_copies" tables, data
> are written to disc by using the "disk_log" module. For
> "disc_only_copies" tables, Mnesia uses "dets".
> What not use the same disk backend ?

Originally, they did use the same back-end, but it turned out,
from experimentation, that dumping the entire table using disk_log
was /much/ faster than writing out the individual changes into
a dets file.

Ulf W
Ulf Wiger
CTO, Erlang Solutions Ltd, formerly Erlang Training & Consulting Ltd



Since January 1st 2010 Erlang Training and Consulting Ltd. has become ERLANG SOLUTIONS LTD.


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