dba_handlers

(PHP 4 >= 4.3.0, PHP 5, PHP 7)

dba_handlers — List all the handlers available

说明

array dba_handlers ([ bool $full_info = false ] )

dba_handlers() list all the handlers supported by this extension.

参数

full_info: Turns on/off full information display in the result.

返回值

Returns an array of database handlers. If full_info is set to TRUE , the array will be associative with the handlers names as keys, and their version information as value. Otherwise, the result will be an indexed array of handlers names.

Note:

When the internal cdb library is used you will see cdb and cdb_make.

范例

Example #1 dba_handlers() Example

  <?php

 echo  "Available DBA handlers:\n" ;
foreach ( dba_handlers ( true ) as  $handler_name  =>  $handler_version ) {
   // clean the versions
   $handler_version  =  str_replace ( '$' ,  '' ,  $handler_version );
  echo  " -  $handler_name :  $handler_version \n" ;
}

 ?>

以上例程的输出类似于：

Available DBA handlers:
 - cdb: 0.75, Revision: 1.3.2.3 
 - cdb_make: 0.75, Revision: 1.2.2.4 
 - db2: Sleepycat Software: Berkeley DB 2.7.7: (08/20/99)
 - inifile: 1.0, Revision: 1.6.2.3 
 - flatfile: 1.0, Revision: 1.5.2.4

用户评论:

[#1] cbemerine at gmail dot com [2009-09-06 05:59:24]

A quick way to see which DBA handlers, without version numbers, that have been built into your version of MySQL on your system, use var_dump with dba_handler() as follows:

<?php var_dump ( "dba_handlers()" ); ?>

Many distros build in these DBA Handlers by default:
array(5) { [0]=>  string(3) "cdb" [1]=>  string(8) "cdb_make" [2]=>  string(3) "db4" [3]=>  string(7) "inifile" [4]=>  string(8) "flatfile" }

using print and pre tags for readability:

array(5) {

  [0]=>

  string(3) "cdb"

  [1]=>

  string(8) "cdb_make"

  [2]=>

  string(3) "db4"

  [3]=>

  string(7) "inifile"

  [4]=>

  string(8) "flatfile"

}

Note there are issues with dba_insert and dba_replace without building for either GDBM or QDBM.
  Here are two sources for the list of DBA handlers: (http://www.php-editors.com/php_manual/ref.dba.html and http://dewa03.unep.org/manuals/php_manual/ref.dba.html; )

CDBM & CDB compiles have issues with updates, you can read databases and write new database files, but you will be prevented from using dba_replace() and you may have issues with dba_insert().

NDBM & DBM are depreciated.

DB2, DB3 & DB4 (Berkeley DB Sleepycat Software / Oracle)  Have read online about issues with dba_replace() and db4 specifically. Make sure you test your installation for correct usage of all DBA functions.

SDBM, TDB, TinyCDB were not listed on most of the sources I have found online.  Those DBA handlers and the names of the developers were listed on the QDBM source forge site.  How they interact with dba_replace() I do not know.  You should be aware of their existence.

GDBM and QDBM are the only other two DBA handlers I am aware of.  Both are reported to allow PHP's dba_replace() function to work correctly so either may be an acceptable option.  The following three restrictions of traditional DBM are not issues for either GDBM or QDBM: 1) a process can handle only one database;  2) the size of a key and a value is bounded;   3) a database file is sparse.

DBA handler benchmark compares QDBM, GDBM, NDBM, SDBM, TDB, CDB, BDB, QDBM-BT-ASC, QDBM-BT-RND, BDB-BT-ASC, BDB-BT-RND can be found here: (http://qdbm.sourceforge.net/benchmark.pdf);

QDBM seems to offer significant improvements in speed over the other DBA Handlers, test in your environment to verify the results.