Apache Reference: mod_auth_db

mod_auth_db - User Authentication by User Name/Password (Berkeley-DB)
Since Apache 1.1, src/modules/standard/mod_auth_db.c
Rob McCool, Brian Behlendorf, Robert S. Thau, Andrew Cohen (1996)

mod_auth_db is another variant of mod_auth that provides the same functionality.Instead of a flat-file database, however, it uses a Berkeley-DB/1.x or Berkeley-DB/2.x hash file. The advantage is a magnitude-better performance in the lookups (performed for every request) which is especially important consideration when the user community is very large. The Berkeley-DB library is usually not provided by UNIX platform vendors, but is more reliable and faster than NDBM libraries.

Directives:

AuthDBAuthoritative	AuthDBGroupFile
AuthDBUserFile