[erlang-questions] Some mnesia oddity

Dan Gudmundsson <>
Tue Oct 7 13:45:47 CEST 2008


Ben Hood wrote:
> Dan,
> 
> On Tue, Oct 7, 2008 at 8:58 AM, Ben Hood <> wrote:
>>> I will probably disallow '_' and '$[1-n]' in mnesia:delete_object.
>> Thanks for the heads up. I will remove all usages of wildcards in
>> mnesia:delete_object/1 calls in our code.
> 
> Just FYI: When I changed the wildcard deletes with exact key matches
> in a loop, the performance of removing entries in this table dropped
> by about 40% in my particular application.
> 
> Is there some way to remove batches of records more efficiently? Would
> it make a difference to use a dirty_delete?

No not today, and I _guess_ that if I implement a match_delete like function
it would cost about the same. The cost is in copying the operations to the
temporary transaction store and searching it when doing the following
operations, I can of course do something special but then that have to be
checked (a performance cost) in every write and read operation.

/Dan
> Thx,
> 
> Ben
> 



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