dba_handlers

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

dba_handlers — 利用可能なハンドラの一覧を得る

説明

dba_handlers(bool $full_info = false): array

dba_handlers() は、この拡張モジュールによりサポートされる全てのハンドラの一覧を返します。

パラメータ

full_info: 結果の全ての情報を表示するかどうかを切り替えます。

戻り値

データベースハンドラの配列を返します。full_info が true の場合、この配列はハンドラ名をキー、そのバージョンを値とする連想配列となります。それ以外の場合はハンドラ名を値に持つ数値添字の配列となります。

注意:
cdb ライブラリが用いられている場合、 cdb および cdb_make が表示されます。

例

例1 dba_handlers() の例

<?php

echo "Available DBA handlers:\n";
foreach (dba_handlers(true) as $handler_name => $handler_version) {
  // バージョン番号を見やすくする
  $handler_version = str_replace('$', '', $handler_version);
  echo " - $handler_name: $handler_version\n";
}

?>

上の例の出力は、たとえば以下のようになります。

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

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User Contributed Notes 1 note

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cbemerine at gmail dot com ¶

15 years ago

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.

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