the way i understand how row caches work is that each node has an independent cache, in that they do not push there cache contents with other nodes.  if that the case is it also true that when a new node is added to the cluster it has to build up its own cache.  if thats the case i see that as a possible performance bottle neck once the node starts to accept requests.  since there is no way i know of to warm the cache without adding the node to the cluster.  would it be infeasible to have part of the bootstrap process not only stream data from nodes but also cached rows that are associated with those same keys?  that would allow the new nodes to be able to provide the best performance once the bootstrap process finishes.

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