Real-Time OLAP Engines

Apache Druid is a real-time analytics database combining ideas from data warehouses, time-series databases, and log search systems, with columnar storage, time-based partitioning, and bitmap indexes serving sub-second queries over streaming data.

Apache Doris is an MPP analytical database for real-time reporting and ad-hoc analysis, speaking MySQL-compatible SQL over a Java front end and a C++ back end, and the project StarRocks was originally forked from.

SingleStore is a commercial distributed SQL database that runs transactional and analytical workloads in one engine, combining rowstore and columnstore tables with vector search, and delivered as the managed Helios service or self-managed.

Tinybird is a managed ClickHouse platform that turns a SQL query into a deployed HTTP endpoint, aimed at developers building real-time analytics into applications rather than operating a database.

TimescaleDB is a PostgreSQL extension that adds automatic time-based partitioning, hybrid row-columnar storage, and incrementally refreshed aggregates, keeping full PostgreSQL SQL and its entire ecosystem of drivers and tools.

QuestDB is an open-source time-series database with a column-oriented, time-partitioned storage engine and SIMD-vectorized execution, extending SQL with time-series operators like SAMPLE BY and ASOF JOIN.

kdb+ is KX's commercial columnar time-series database, long the standard for financial tick data, queried through the vector language q rather than standard SQL.

CrateDB is an open-source distributed SQL database for real-time analytics and search, querying relational, JSON, time-series, geospatial, vector, and full-text data through one PostgreSQL-compatible interface.

GreptimeDB is an open-source observability database handling metrics, logs, and traces in one Rust engine, with columnar storage on object storage and both SQL and PromQL as query languages.

Apache Pinot is a distributed real-time OLAP store built to serve analytical queries at very high concurrency with millisecond latency, ingesting directly from streams.

StarRocks is an open-source MPP OLAP database combining streaming ingest, strong join performance at query time, and direct querying of lakehouse table formats.

ClickHouse is an open-source columnar database designed for low-latency analytical queries over large volumes, available self-hosted or as ClickHouse Cloud.