berkeley db和db4的安装

bdb安装程序：

1、安装Berkeley DB

# cd /usr/local/src
# wget
# tar -zxvf db-4.6.21.tar.gz
# cd db-4.6.21
# cd build_unix

Berkeley DB默认是安装在/usr/local/BerkeleyDB.4.6目录下，其中4.6就是版本号，你也可以指定–prefix参数来设置安装目录

# ../dist/configure --prefix=/usr/local/berkeleydb --enable-cxx

其中–enable-cxx就是编译C++库，这样才能编译Berkeley DB数据库的PHP扩展php_db4

# make
# make install
# echo '/usr/local/berkeleydb/lib/' >> /etc/ld.so.conf
# ldconfig

这2句的作用就是通知系统Berkeley DB的动态链接库在/usr/local/berkeleydb/lib/目录。
如果没有系统提示ldconfig命令，则用whereis ldconfig找一下在哪，一般可用 # /sbin/ldconfig
至此，Berkeley DB数据库已经安装完成。

2、安装Berkeley DB的PHP扩展

虽然PHP里已经自带了php_db和php_dba两个扩展都支持Berkekey DB，但是毕竟支持的有限，所以还是编译Berkeley DB自带的php_db4扩展好。

# cd /usr/local/src/db-4.6.18/php_db4/
# phpize（/usr/local/php/bin/phpize）
# ./configure --with-db4=/usr/local/berkeleydb/ --with-php-config=/usr/local/php/bin/php-config
# make
# make install

说明：这里configure的时候可能会提示你找不到php-config，你可以找到你的php安装PATH，然后增加--with-php-config=PATH
至此db4已编译好在/usr/lib64/php/modules/db4.so目录(具体跟你的系统有关)

echo 'extension=db4.so' > /etc/php.d/db4.ini

重起WEB服务器(Apache等)
至此php_db4扩展的安装也完成了，执行php -m即可看到db4扩展已经加载了。

3、测试php_db4扩展php_db4提供了下面4个类：

class Db4Env {
    function Db4Env($flags = 0) {}
    function close($flags = 0) {}
    function dbremove($txn, $filename, $database = null, $flags = 0) {}
    function dbrename($txn, $file, $database, $new_database, $flags = 0) {}
    function open($home, $flags = DB_CREATE | DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL | DB_INIT_TXN, $mode = 0666) {}
    function remove($home, $flags = 0) {}
    function set_data_dir($directory) {}
    function txn_begin($parent_txn = null, $flags = 0) {}
    function txn_checkpoint($kbytes, $minutes, $flags = 0) {}
}

class Db4 {
    function Db4($dbenv = null) {} // create a new Db4 object using the optional DbEnv
    function open($txn = null, $file = null, $database = null, $flags = DB_CREATE, $mode = 0) {}
    function close() {}
    function del($key, $txn = null) {}
    function get($key, $txn = null, $flags = 0) {}
    function pget($key, &$pkey, $txn = null, $flags = 0) {}
    function get_type() {} // returns the stringified database type name
    function stat($txn = null, $flags = 0) {} // returns statistics as an as
    function join($cursor_list, $flags = 0) {}
    function sync() {}
    function truncate($txn = null, $flags = 0) {}
    function cursor($txn = null, flags = 0) {}
}

class Db4Txn {
    function abort() {}
    function commit() {}
    function discard() {
    function id() {}
    function set_timeout($timeout, $flags = 0) {}
}

class Db4Cursor {
    function close() {}
    function count() {}
    function del() {}
    function dup($flags = 0) {}
    function get($key, $flags = 0) {}
    function pget($key, &$primary_key, $flags = 0) {}
    function put($key, $data, $flags = 0) {}
}
从字面上也不难理解，Db4Env设置数据库环境、Db4操作数据库、Db4Txn用于事务处理、Db4Cursor用于光标处理。具体使用可参考
http://www.oracle.com/technology/documentation/berkeley-db/db/ref/ext/php.html
/usr/local/src/db-4.6.18/php_db4/samples目录下提供了2个简单的例子simple_counter.php和transactional_counter.php。

simple_counter.php

// Create a new Db4 Instance
$db = new Db4();

// Open it outside a Db4Env environment with datafile/var/lib/db4
// and database name "test"
$db->open(null, "/var/tmp/db4", "test");

// Get the current value of "counter"
$counter = $db->get("counter");
print "Counter Value is $counter\n";

// Increment $counter and put() it.
$db->put("counter", $counter+1);
// Sync to be certain, since we're leaving the handle open
$db->sync();
?>

transactional_counter.php

// Open a new Db4Env
$dbenv = new Db4Env();
$dbenv->set_data_dir("/var/tmp/dbhome");
$dbenv->open("/var/tmp/dbhome");

// Open a database in $dbenv. Note that even though
// we pass null in as the transaction, db4 forces this
// operation to be transactionally protected, so PHP
// will force auto-commit internally.
$db = new Db4($dbenv);
$db->open(null, 'a', 'foo');

$counter = $db->get("counter");
// Create a new transaction
$txn = $dbenv->txn_begin();
if($txn == false) {
print "txn_begin failed";
exit;
}
print "Current value of counter is $counter\n";

// Increment and reset counter, protect it with $txn
$db->put("counter", $counter+1, $txn);

// Commit the transaction, otherwise the above put() will rollback.
$txn->commit();
// Sync for good measure
$db->sync();
// This isn't a real close, use _close() for that.
$db->close();
?>