科技回声

What are other databases like SQlite, which dont require spinning up a server & save data to disk instead? Does such a thing exist for specialized databases on a single disk (elastic search etc)?

Berkeley DB and variants:<a href="https://en.wikipedia.org/wiki/Berkeley_DB" rel="nofollow">https://en.wikipedia.org/wiki/Berkeley_DB</a>

There's duckdb which seems very similar. I haven't actually used it for anything yet so YMMV.

Firebird, maybe:<a href="https://firebirdsql.org/manual/fbint-structure.html" rel="nofollow">https://firebirdsql.org/manual/fbint-structure.html</a>

Apache H2, and Apache Derby. There's quite a few that are available if you only need them to be supported on the JVM.

<a href="https://ejdb.org/" rel="nofollow">https://ejdb.org/</a>standalone nosql

What are your requirements (data model, non-functional priorities, data size, data types)?