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 previous().
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:
for i in xrange(1, len(db)):
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.