ybio is a PL/pgSQL-based load generator for PostgreSQL and YSQL, specifically designed for flexible IO testing in YugabyteDB. It can perform various types of stress tests on specific parts of the database infrastructure without requiring client installation. ybio differs from other benchmark tools like pgbench, focusing solely on stress testing the database server side rather than simulating application execution patterns. The tool is highly customizable with a range of configuration options that allow users to test different aspects of their database, such as primary key settings, index types, and tablet configurations. By leveraging its PL/pgSQL-based architecture and running inside YSQL, ybio can stress the database maximally without being bound by client tool network limits. This allows for a wide range of tests to be performed on various parts of the database, including selectivity, update, delete, and insert operations, making it an ideal tool for database administrators and developers looking to optimize their YugabyteDB performance.