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54 lines
3.2 KiB
Plaintext
54 lines
3.2 KiB
Plaintext
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These functions build the foundation for accessing Berkeley DB style
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databases.
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This is a general abstraction layer for several file-based databases. As
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such, functionality is limited to a common subset of features supported
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by modern databases such as Sleepycat Software's DB2. (This is not to be
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confused with IBM's DB2 software, which is supported through the ODBC
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functions.)
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This extensions allows to work with the following databases:
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dbm DBM is the oldest (original) type of Berkeley DB style databases.
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You should avoid it, if possible. We do not support the
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compatibility functions built into DB2 and gdbm, because they are
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only compatible on the source code level, but cannot handle the
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original dbm format.
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ndbm NDBM is a newer type and more flexible than dbm. It still has
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most of the arbitrary limits of dbm (therefore it is deprecated).
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gdbm GDBM is the GNU database manager.
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db2 DB2 is Sleepycat Software's DB2. It's described as "a programmatic
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toolkit that provides high-performance built-in database support
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for both standalone and client/server applications.
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db3 DB3 is Sleepycat Software's DB3.
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db4 DB4 is Sleepycat Software's DB4. This is available since PHP 5.0.
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cdb CDB is "a fast, reliable, lightweight package for creating and
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reading constant databases." It is from the author of qmail and
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can be found at http://cr.yp.to/cdb.html. Since it is constant,
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we support only reading operations. And since PHP 4.3.0 we support
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writing (not updating) through the internal cdb library.
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cdb_make Since PHP 4.3.0 we support creation (not updating) of cdb files
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when the bundled cdb library is used.
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flatfile This is available since PHP 4.3.0 for compatibility with the
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deprecated dbm extension only and should be avoided. However you
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may use this where files were created in this format. That happens
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when configure could not find any external library.
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inifile This is available since PHP 4.3.3 to be able to modify php.ini
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files from within PHP scripts. When working with ini files you
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can pass arrays of the form array(0=>group,1=>value_name) or
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strings of the form "[group]value_name" where group is optional.
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As the functions dba_firstkey() and dba_nextkey() return string
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representations of the key there is a new function dba_key_split()
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available since PHP 5 which allows to convert the string keys into
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array keys without loosing FALSE.
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qdbm This is available since PHP 5.0.0. The qdbm library can be loaded
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from http://qdbm.sourceforge.net.
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After configuring and compiling PHP you must execute the following test
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from commandline:
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php run-tests.php ext/dba.
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This shows whether your combination of handlers works. Most problematic
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are dbm and ndbm which conflict with many installations. The reason for
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this is that on several systems these libraries are part of more than one
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other library. The configuration test only prevents you from configuring
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malfaunctioning single handlers but not combinations.
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