Efficient Concurrent Range Queries in B+-trees using RCU-HTM

Abstract

In this work, we exploit RCU-HTM, a synchronization mechanism that combines Read-Copy-Update (RCU) and Hardware Transactional Memory (HTM) to support linearizable and highly efficient range queries in a concurrent B+-tree. Range queries in our B+-tree start with an asynchronized traversal and then perform a horizontal scan of leaf nodes, by following sibling pointers, using hardware transactions. Despite its simplicity, our RCU-HTM based B+-tree with range query support greatly outperforms state-of-the-art map data structures for range queries in several execution scenarios.