dbhash — DBM-style interface to the BSD database library
Deprecated since version 2.6: The
dbhash module has been removed in Python 3.
dbhash module provides a function to open databases using the BSD
db library. This module mirrors the interface of the other Python database
modules that provide access to DBM-style databases. The
bsddb module is
required to use
This module provides an exception and a function:
Exception raised on database errors other than
KeyError. It is a synonym for
open(path[, flag[, mode]])
dbdatabase and return the database object. The path argument is the name of the database file.
The flag argument can be:
Open existing database for reading only (default)
Open existing database for reading and writing
Open database for reading and writing, creating it if it doesn’t exist
Always create a new, empty database, open for reading and writing
For platforms on which the BSD
dblibrary supports locking, an
'l'can be appended to indicate that locking should be used.
The optional mode parameter is used to indicate the Unix permission bits that should be set if a new database must be created; this will be masked by the current umask value for the process.
11.10.1. Database Objects
The database objects returned by
open() provide the methods common to all
the DBM-style databases and mapping objects. The following methods are
available in addition to the standard methods.
It’s possible to loop over every key/value pair in the database using this method and the
next()method. The traversal is ordered by the databases internal hash values, and won’t be sorted by the key values. This method returns the starting key.
Return the last key/value pair in a database traversal. This may be used to begin a reverse-order traversal; see
Returns the key next key/value pair in a database traversal. The following code prints every key in the database
db, without having to create a list in memory that contains them all:
print db.first() for i in xrange(1, len(db)): print db.next()
Returns the previous key/value pair in a forward-traversal of the database. In conjunction with
last(), this may be used to implement a reverse-order traversal.
This method forces any unwritten data to be written to the disk.