Just another embedded SQL engine. There are SQLite(OLTP), DuckDB(OLAP) and some engine-based project like mentioned Apache Arrow(https://arrow.apache.org/)(OLA

Just another embedded SQL engine. There are SQLite(OLTP), DuckDB(OLAP) and some engine-based project like mentioned Apache Arrow(https://arrow.apache.org/)(OLAP) https://arrow.apache.org/)(OLAP): Apache Arrow has many language implementations, some do not include the query engine(for example, Rust implementation, which depends on the DataFusion for more SQL-like analytics) in its own repo, but other do include(for example, C++). There is a comprehensive benchmark by ClickHouse for OLAP but including kinds of embedding engines: https://benchmark.clickhouse.com/ https://benchmark.clickhouse.com/ The more interesting is that, in fact, we have not an embedded HTAP engine. One of my database products already implements 3/4 HTAP at the engine layer, but unfortunately it's still just a free software, not an open source implementation.