An Apache HAWQ developer designs, develops, and maintains the HAWQ system, an advanced enterprise SQL-on-Hadoop solution. They work on enhancing its features, improving its performance, and fixing bugs. This involves understanding the Hadoop ecosystem, SQL database systems, and data processing engines. They also collaborate with other developers, write clean, efficient code, and ensure the system meets user needs. Moreover, they must adhere to best practices for software development, conduct testing to ensure system reliability, and provide support for any technical issues. They may also write documentation and provide training for users.