The behaviour of various aspects depends on the
implementation of the underlying database. Functions such as
dba_optimize() and dba_sync() will do what they promise for one
database and will do nothing for others. You have to download and
install supported dba-Handlers.
|dbm||Dbm is the oldest (original) type of Berkeley DB style
databases. You should avoid it, if possible. We do not support the
compatibility functions built into DB2 and gdbm, because they are
only compatible on the source code level, but cannot handle the
original dbm format.
|ndbm||Ndbm is a newer type and more flexible than dbm. It still has
most of the arbitrary limits of dbm (therefore it is
|gdbm||Gdbm is the » GNU database manager.|
|db2||DB2 is for » Oracle Berkeley DB 2. It is
described as “a programmatic toolkit that provides high-performance
built-in database support for both standalone and client/server
|db3||DB3 is for » Oracle Berkeley DB 3.|
|db4||DB4 is for » Oracle Berkeley DB 4 or 5. This
option can be used with BDB 5 as of PHP 5.3.3.
|cdb||Cdb is “a fast, reliable, lightweight package for creating and
reading constant databases.” It is from the author of qmail and can
be found at » http://cr.yp.to/cdb.html. Since it
is constant, we support only reading operations. We support writing
(not updating) through the internal cdb library.
|cdb_make||We support creation (not updating) of cdb files when the
bundled cdb library is used.
|flatfile||This is available for compatibility with the deprecated
dbm extension only and should be avoided. However you may
use this where files were created in this format. That happens when
configure could not find any external library.
|inifile||This is available to be able to modify php.ini files from
within PHP scripts. When working with ini files you can pass arrays
of the form array(0=>group,1=>value_name) or strings of the
form “[group]value_name” where group is optional. As the functions
dba_firstkey() and dba_nextkey() return string representations
of the key there is the function dba_key_split() which allows to convert the
string keys into array keys without loosing
|qdbm||The qdbm library can be downloaded from » http://fallabs.com/qdbm/index.html.|
|tcadb||This is available since PHP 5.4.0. The Tokyo Cabinet library
can be downloaded from » http://fallabs.com/tokyocabinet/.
|lmdb||This is available since PHP 7.2.0. The Lightning Memory-Mapped
Database library can be downloaded from » https://symas.com/lmdb/.
When invoking the dba_open() or
dba_popen() functions, one of the handler
names must be supplied as an argument. The actually available list
of handlers is displayed by invoking phpinfo() or dba_handlers().