A method in a computer system executing a client application and an OODBMS and an RDBMS software, which system has a storage medium accessible by the RDBMS software and the OODBMS software being accessible by the client application. The method generates unique object identifiers in a data abstraction layer disposed between the OODBMS and the RDBMS software in response to a parent thread created by the client application. The method includes the steps of creating a child thread that has access to the RDBMS software, which child thread is used exclusively for generating object identifier numbers and for returning the same to the parent thread. A unique object identifier table is created, which is maintained by the child thread. In response to a request by the parent thread for a unique object identifier, the child thread generates a finite number of the unique object identifiers and communicates their values to the parent thread. After this, a recording is made in the table of the fact that a finite number of unique object identifiers have been generated.