You are absolutely right. Just an addendum: there are modern B-Trees that are optimised to leverage the cache lines, part of the so called cache oblivious data structures ( http://erikdemaine.org/papers/CacheObliviousBTrees_SICOMP/pa... ). A cache oblivious B-Tree is the basis of Percona's TokuDB storage engine: https://www.percona.com/doc/percona-tokudb/ft-index.html