Mnesia dB size limits
Wed Aug 30 23:34:24 CEST 2006
How many times are the same people going to give the same "answers". This is
----- Original Message -----
From: "Yariv Sadan" <>
To: "Joel Reymont" <>
Cc: "Philip Robinson" <>; <>;
Sent: Wednesday, August 30, 2006 7:41 PM
Subject: Re: Mnesia dB size limits
> AFAIK the problems with Mnesia isn't that you can't insert a lot of
> data into it, but the following:
> 1) in the event of a crash, a very large dets table takes a long time to
> 2) there are no join optimizations (yet), so some queries can take a
> long time to process
> 3) as the dets freelist gets fragmented it consumes more and more memory.
> None of these items means you can't put a lot of data in Mnesia --
> they just mean that you may run into problems if you do.
> With ets tables, issues 1) and 3) go away.
> On 8/30/06, Joel Reymont <> wrote:
>> I have a suspicion that when people mention that Mnesia is great with
>> huge data sets they unintentionally forget to mention important
>> details. My understanding is that call record databases are insert/
>> retrieve only or for the most part.
>> When people outside of the telco world ask about Mnesia they usually
>> have MySQL, etc. in mind and wonder about insert/delete/update
>> performance. My understanding at the moment is that Mnesia is not the
>> best database for insert/update/delete, much less with huge databases.
>> Please correct me if I'm wrong!
>> On Aug 30, 2006, at 4:10 PM, Philip Robinson wrote:
>> > I was once writing a program that needed to retrieve events
>> > within a date/time range from an mnesia table, and found that it
>> > did not seem to be hitting the index. It would scan the entire
>> > 1-million-plus records every query... dead slow.
>> > When I wanted to retrieve a specific event there was no noticable
>> > delay, but most of my queries were for a date/time range.
>> > I think the mnesia issues being mentioned on this list were to do
>> > with database recovery across nodes after a node failure...?
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