The Relativity DBMS (Database Management System) is software that implements an ODBC-compliant and relational database view of actual, operational COBOL data files. The Relativity DBMS also can take instructions from the ODBC-enabled application to access and change data in the COBOL data files. The ODBC-enabled application issues a high-level command, called an SQL statement, describing the data that the application wants to access. The Relativity DBMS performs the same actions a COBOL program would perform in order to extract that data and then returns the data to the ODBC-enabled application in the form of "rows".
The Relativity DBMS comes in two different configurations. In the single-tier or non-client/server configuration, the complete Relativity DBMS resides on a single Windows machine. The single-tier configuration component of the Relativity DBMS is referred to as the Relativity Data Manager. In the two-tier or client/server configuration, the Relativity DBMS is split into two components so that the DBMS can reside on two machines. The two-tier components of the Relativity DBMS are referred to as the Relativity Data Client and the Relativity Data Server. See also data source and catalog.