A Database Administrator is a person responsible for managing the enterprise databases for an institution. These databases include support for Sakai and other systems, such as a student information system, registrar system, finanical system, etc.
DBAs are usually reponsible for installing and configuring databases and their associated tables. They are often consulted to improve overall system performance by tuning table structures and queries against them. Since database systems differ considerably in their capablities (even from version to version), this can be highly specialized knowledge.