database engines are one of the strength for progress.it has two db engines-sql92 and 4gl.4GL concepts is also a great strength for progress database.

sql92 and 4gl engines are different but both can be used against a single database. even installing sql92 engine doesn't reduce the performance of 4gl engines.u can say bith engines as a security models for the database.

these engines wil take care during crash of database recovery prosess from storage devices(ai bi tl).sql clients can connect thro sql92 engine and 4gl clients can connect thro 4gl engine.