5. Database Files

The WFDB library has been constructed to provide a standard interface between the database files and application programs. Alternate means of access to database files is strongly discouraged, since file formats may change. Database files are located in the directories specified by WFDB (see section The Database Path and Other Environment Variables).

Recall that a WFDB record is not a file; rather, it is an extensible collection of database files (see section Records). Thus, for example, record 100 of the MIT-BIH Arrhythmia Database consists of the files named ‘100.hea’, ‘100.dat’, and ‘100.atr’ in the ‘mitdb’ directory of the MIT-BIH Arrhythmia Database CDROM (or in PhysioBank, within http://physionet.org/physiobank/database/mitdb/), together with any additional files in other directories that you may have associated with record 100 (such as your own annotation file). All files associated with a given record include the record name as the first part of the file name. No explicit action (other than choosing the file name, and locating the file in the WFDB path) is needed in order to associate a new file with an existing WFDB record.

To find the location of a database file easily, you can use ‘wfdbwhich’, an application included with the WFDB Software Package. Type wfdbwhich for brief instructions on its use, or see the WFDB Applications Guide.