The module implements the most basic log-structured merge tree store primitives. An LSM-tree is the most common database structure after the B-tree. One chunk of an LSM tree is often called an SST (sorted strings table). It is a log of key-value records sorted in the ascending order. See the Petrov’s Database Internals book for the particulars.
The key LSM algorithm is the chunk merge, working very much like a merge sort.
The LSMnext/LSMmerge routines implement exactly that: merge by a heap of iterators.
The contents of the chunks are supposed to be sorted ToyTLV key-value records.