I think actually this competes with the old BerkeleyDB: https://en.wikipedia.org/wiki/Berkeley_DB - which I now see is no longer BSD-licensed, and in any case has been rendered almost extinct by SQLite. It was used for basic on-disk key-value store work.
It seems more like SSTables, which are widely used by open-source software like LevelDB, HBase, and Cassandra (and Google's BigTable) but AFAIK don't have a standard open-source reader (unless you want to pull the relevant source file out of Cassandra or LevelDB).
Yes this does seem almost exactly like what PeakSlab is doing. I'll have to investigate more how SSTables and memtables work to see if there's any improvements or anything to glean from them.
I'm storing null delimited sorted strings with an index that's an offset to where that entry begins, so if I wanted to do memtables for writing I would have to have two memtables and merge them on write? I've been considering this exact approach.
Even BerkeleyDB tries to be mutable. What I'm doing doesn't need the mutability so it's much more similar to dictionary formats (though probably simpler) than it is to a database. Though a lot of people do use full databases for immutable dictionary key-value stuff. I just couldn't get any database to work well enough for a pwa dictionary.
