Wikipedia
LucidDB
LucidDB is an open source database purpose-built to power data warehouses, OLAP servers and business intelligence systems.
LucidDB is the first and only open-source RDBMS purpose-built entirely for data warehousing and business intelligence. It is based on architectural cornerstones such as column-store, bitmap indexing, hash join/aggregation, and page-level multiversioning.
Due to its purpose built architecture and features designed for BI and Data Warehouse workloads it typically performs faster than traditional row store databases, without any additional tuning.