The document discusses big data and open-source relational database management systems (RDBMSs). It begins by introducing the speaker and their background in cloud architecture and enterprise databases. The rest of the document summarizes various RDBMS options for big data, including PostgreSQL and extensions like Citus and Timescale, as well as columnar databases like Greenplum and Clickhouse. It compares the systems based on their SQL support, integration capabilities, data ingestion styles and performance, support for wide tables versus star schemas, horizontal scaling abilities, and availability as managed cloud services.