This sounds like a job for Zookeeper (distributed coordination is what it does).
Take a look at: http://zookeeper-user.578899.n2.nabble.com/Sequence-Number-Generation-With-Zookeeper-td5378618.html On Wed, Mar 6, 2013 at 10:00 AM, mark12345 <marks1900-pos...@yahoo.com.au> wrote: > Appending a random value only reduces the chance of a collision (And I need > to ensure continuous uniqueness) and could hurt how the field is later > sorted. I have not written a custom UpdateRequestProcessor before, is there > a way to incorporate a Singleton that ensures one instance across a cluster? > SolrCloud? > > I guess the main thing is that I want the value would also be kept unique > across a cluster of Solr instances. As far as I know in Solr, the only > *free* uniqueness check is with the "<uniqueKey>id</uniqueKey>" declaration > in "schema.xml". Are there other options that I should be considering? > > > > -- > View this message in context: > http://lucene.472066.n3.nabble.com/Solr-4-x-auto-increment-sequence-counter-functionality-tp4045125p4045239.html > Sent from the Solr - User mailing list archive at Nabble.com.