Files that contain project compilation data which are generated by the Quartus^® II software. Database files are created, used internally, and updated by the software during compilation, simulation, and other processes. You can re-create database files by recompiling or resimulating. The following are database file types:

• Compiler Database File (.cdb)
• Hierarchy Database File (.hdb)
• Report Database File (.rdb)
• Timing Database File (.tdb)

A Compiler Netlist File (.cnf) is another type of database file, and is either a CDB File with the file name <compilation focus name>.cnf.cdb or an HDB File with the file name <compilation focus>.cnf.hdb.