I'm trying to figure out whether there's an easy way to accomplish something like a "recursive/looping map-reduce query" in Riak.
A use case for this is when the objects in the database form a linked list, tree, or graph of some kind, and you want to look up a set of objects whose depth from the initial key set isn't known in advance. For a simple example, say you have a log of events that are stored as a linked list of blocks of some maximum size, and you want to retrieve the most recent n events that have some property (which for whatever reason isn't practical to index in advance). It's easy to write a function that looks up each block in order and stops when it has n matches, but it would be nice to do this without O(n) roundtrips to Riak and possibly having to discard a large fraction of the results on the client side. One hack solution would be to write a map-reduce query with some large number of identical pairs of map and reduce phases, where once the stopping condition is met, the subsequent phases will get a flag in their input which makes them a cheap no-op. Are there any other options short of running custom query-coordinating code at the level of riak_pipe? Thanks, Mike _______________________________________________ riak-users mailing list riak-users@lists.basho.com http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
