#include <db.h> int DB→open(DB *db, const char *file, const char *database, DBTYPE type, u_int32_t flags, int mode);
The currently supported Berkeley DB file formats (or access methods) are Btree, Hash, Queue, and Recno. The Btree format is a representation of a sorted, balanced tree structure. The Hash format is an extensible, dynamic hashing scheme. The Queue format supports fast access to fixed-length records accessed sequentially or by logical record number. The Recno format supports fixed- or variable-length records, accessed sequentially or by logical record number, and optionally backed by a flat text file.
Storage and retrieval for the Berkeley DB access methods are based on key/data pairs; see “DBT” for more information. ...