that's a hybrid compacting data structure: compacting within the btree node, normal btree topology otherwise. And it works much better than pure compacting (i.

that's a hybrid compacting data structure: compacting within the btree node, normal btree topology otherwise. And it works much better than pure compacting (i.e. the leveldb lineage), because you avoid lock contention at the root on multithreaded update workloads, and the compaction/resort is much lower overhead when it fits in l2. incidentally, there's a filesystem that uses this technique.