[SR-Users] mtree on db Berkeley DB?

[Douglas Hubler]

On Mon, Nov 14, 2011 at 5:10 AM, Daniel-Constantin Mierla
<miconda at gmail.com> wrote:
> are there any other no-sql database systems that have such mechanism? Might
> not be hard to make a connector when the time will allow -- just to know the
> best options here.

mongodb will auto promote.  Caveat, (like redis if i understand
correctly), is that all writes are directed to a single master (be it
chosen dynamically), but reads can happen anywhere to spread the load.
 Also, you need to accept the distaster scenario of a "network
partition"  where a minority set of servers find themselves w/o a
master.  Example: 5 servers in datacenter #1 and 4 servers in
datacenter #2.  If the link between datacenters is broken, then all
servers in datacenter #2 will not have a master and will be read-only
until link is restored.  Good part about single master is there's no
chance of inconsistent data.

Turns out local fail-over v.s. consistent data is a well explored area.

 http://blog.nahurst.com/visual-guide-to-nosql-systems

I've worked w/the C++ driver to mongodb is anyone has questions.