ordered_set in mnesia

Sean Hinde <>
Thu Jul 12 20:19:05 CEST 2001


Hi 
I am wondering about the table_type ordered_set in Mnesia, the documentation

mentions that You can create a table with type ordered set but I can not
really 
find any operations to access it.  

The table is accessed by all the same operations used for set and bag
tables. (read, write etc).


The only operations I can find are dirty_first and dirty_next which is not
what I want. 
Are there no clean first and next operations?  

As I understand it there is no difference between dirty_first and what would
be a first command. dirty_read and dirty_next are perfectly safe to use in
transactions (dirty_write isn't but that is to be expected).

What I want to do is to have a persistent queue implemented in Mnesia, any 
suggestions on how to do it without ordered set? 
I need the transaction support in mnesia, and the distribution could be
useful to 
in the future.  

I reimplemented the timer module as a contrib on www.erlang.org
<http://www.erlang.org>  which used an mnesia ordered set as the timer queue
and also used transactions. (This was before I discovered erlang:start_timer
and erlang:send_after ;) ). You might find something of interest in there..

Rgds,

Sean




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