QuestDB is an open-source SQL database designed to process time-series data, faster.
It uses a column-oriented approach, vectorized execution, SIMD instructions, and a whole array of low-latency techniques. The whole code base is built from scratch and without dependencies, in the name of performance. QuestDB is 100% free from garbage collection.
QuestDB implements SQL, and augments it for time-series. It exposes a Postgres wire protocol, a high-performance REST API, and even supports ingestion with InfluxDB line protocol. It supports both relational and time-series joins, which makes it easy to correlate data over time. Writes are durably committed to disk, meaning that the data is safe - yet instantly accessible.
QuestDB was born as a side project from Vlad Ilyushchenko and took principles and inspiration from low latency techniques found in the financial services industry. This link goes through the entire backstory of QuestDB through its Hacker News launch
Relational model, optimised for time-series