RavenDB Master / Master Document Key Generation

[Alex Spence]

I did some quick searching and haven't found anything explaining this in detail.  If I have RavenDB running in Master / Master configuration in 3 different datacenters, and I let RavenDB Generate DocumentKeys, how does RavenDB avoid document key collisions ?  I has been working fine for us for quite some time, but suddenly we got some serious conflicts.  I think this was due to a network outage between the datacenters... I'm just looking for a quick explanation as to how it works, I will likely start varying my keys by datacenter just to be safe.

[Anders Strömberg]

RavenDB does not do anything to avoid conflicts in document keys, each database hands out ranges of an increasing number series to each client. To handle conflicts in master-master replications have a look at the bottom paragraph of 

http://ravendb.net/docs/2.5/server/scaling-out/replication/client-integration

BR

Anders

[Oren Eini (Ayende Rahien)]

Yes, see the Raven/ServerPrefixForHilo:.

In 3.0, you can configure that directly in the studio. 

Oren Eini

CEO

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[Alex Spence]

Thanks for the responses, I can't believe we have not run into this before.. I guess we just got lucky.  Well for now varying the key by datacenter will solve my problem but I will be more careful with master / master keys from now on.  And as soon as we can upgrade to 3.0 I will check out the new settings for server prefix.

[Oren Eini (Ayende Rahien)]

Note that this is _already there in 2.5_, we just don't have the UI for it.