IEEE Standards Interpretations for IEEE Std 1003.1™-2001 IEEE Standard for Information Technology - Portable Operating System Interface (POSIX®)
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Interpretation Request #42
Topic:dbm_open implementation of database files Relevant Sections: XSH dbm_open
"The database is stored in two files. One file is a directory containing a bit map of keys and has .dir as its suffix. The second file contains all data and has .pag as its suffix." Implementations of the Berkeley DB interface have evolved while remaining db(3) compatible. Different implementations use different on-disk formats and naming conventions which should not be a part of the standard, the API defines the standard and always has.
The following wording should be removed from the standard. "The database is stored in two files. One file is a directory containing a bit map of keys and has .dir as its suffix. The second file contains all data and has .pag as its suffix." "The function opens two files named file.dir and file.pag."
The standards states the requirements for the dbm_* functions and their database implementation, and conforming implementations must conform to this. However, concerns have been raised about this which are being referred to the sponsor.
Rationale for Interpretation
The current standard describes a specific implementation for storage of a database excluding common existing practise which has evolved yet remained compatible at the application programming interface.