[erlang-questions] Which distributed key-value storage do you use?

Ulf Wiger ulf.wiger@REDACTED
Thu Aug 13 01:30:29 CEST 2009

Dave Smith wrote:
> On Wed, Aug 12, 2009 at 2:19 PM, Ulf
> Wiger<ulf.wiger@REDACTED> wrote:
>> Personally, I think that disc_only copies seldom have a
>> place nowadays, since they are limited to 2 GB, and
>> 64-bit Erlang allows you to go way beyond that limit with
>> disc_copies and good performance.
> I apologize if this is a stupid question, but I was under the
> impression that using mnesia w/ disc_copies meant that your entire
> data set has to fit in RAM? For most large-scale datasets, even with a
> lot of RAM, that makes mnesia not really desirable as you'd get a low
> density of data-to-node (i.e. I can put  1 TB of disk in a node but
> probably can't afford that much RAM).

I was just pointing out that given the 2 GB limit of dets,
disc_copies is almost always the better option.

Your entire data set doesn't have to fit in RAM on a single
node. Using table fragmentation, you can scale further.

Still, mnesia was not designed for TB databases, and if that
is what you need, you need to look for other solutions.

OTOH, the ODBC library allows you to connect to such DBMSs.

Ulf W
Ulf Wiger
CTO, Erlang Training & Consulting Ltd

More information about the erlang-questions mailing list