CrateDB is targeted specifically at IoT applications and ingesting and processing machine data, and it can be deployed both at the edge and more centrally.
CrateDB is a NewSQL database. That is, it is a distributed, lock-free, ANSI standard SQL database with a fully searchable document data store underpinning the database management system. It is open source, written in Java, and based on a shared nothing architecture. The product is effectively multi-model in that it supports JSON documents, relational data, geospatial, full text, binary large objects (BLOBs) and offers time-series capabilities. While not a native time-series database it supports this because you can partition the data by any function, and that includes time as a function.