Persistent Cache-oblivious Streaming Indexes

In [SPAA2007], Bender et al. define a streaming B-tree (or index) as one that supports updates in amortized o(1) IOs, and present a structure achieving amortized O((logN)/B) IOs and queries in O(logN) IOs. We extend their result to the partially-persistent case. For a version v, let Nv be the number of keys accessible at v and N be the total number of updates. We give a data structure using space O(N), supporting updates to a leaf version v with O((logNv)/B) amortized IOs and answering range queries returning Z elements with O(logNv + Z/B) IOs on average (where the average is over all queries covering disjoint key ranges at a given version). This is the first persistent ‘streaming’ index we are aware of, i.e. that supports updates in o(1) IOs and supports efficient range queries.