[erlang-questions] mnesia:update_element

Musumeci, Antonio S <>
Wed Sep 15 13:29:20 CEST 2010


Obviously there are ways to simulate it but there are situations where you don't care to read then write in a transaction. Where you could do a dirty read and then a dirty update_element. That's going to be faster than dirty read, transaction(wread + write).

-----Original Message-----
From:  [mailto:] On Behalf Of Pascal Chapier
Sent: Wednesday, September 15, 2010 4:44 AM
To: 
Subject: [erlang-questions] mnesia:update_element


Hello,

Concerning Mnesia there is a powerful update mechanism with:
  mnesia:transaction(UpdateFunc(Parameters)),


I am not sure that one can find a simpler and more general update(Element) model for actions such as

   add to cart

   remove from cart

   apply 10% discount

   modify phone number...

it can be faster in some cases:

mnesia:dirty_read, updateFunc, mnesia:dirty_write if concurrency is not a problem,

mnesia:dirty_write(#my_table{key = Key, item=Value}), if only item has to be overwritten and my_table is a set (concurrency ?).

PC

 		 	   		  
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