PHP + XML cache how to quickly read the specified value

PHP + XML cache how to quickly read the specified value the XML cache structure is & nbsp;-& lt; channel & gt; & nbsp;-& lt; item & gt; & nbsp; & lt; id & gt; 1 & lt; id & gt; & nbsp; & lt; pd & gt; B007 & lt; pd & gt; & nbsp; & lt; item & gt; & PHP + XML cache how to quickly read the specified value
Cache with XML
Structure is

-
-
1
B007

-
2
B001

-
3
B000

-
4
B004

-
5
B003

..............




Large data volume

Now I want to quickly find
Id = 4 pd value
Or all the values of items under id = 4
What should I do?

Another question is, can xml support dynamic reading of values?
For example, a. xml? Id = 4
This type
Yes? Thank you.

Yes for PHP

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Reference: http://topic.csdn.net/u/20120521/03/527bc4d2-b4e0-4d6e-9ae4-021a675cfff5.html
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PHP code

$ Xml = simplexml_load_file ('BB. XML'); foreach ($ xml-> item as $ v) {if ($ v-> id = 4) echo "id: $ v-> id
Pd: $ v-> pd ";}
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Xpath. Are there other answers.


  
  

   
   
PHP code
   
   
[User:root Time:10:28:18 Path:/home/liangdong/php]$ php xpath.php pd B004[User:root Time:10:28:19 Path:/home/liangdong/php]$ cat xpath.php 
      
      
     
      1
       
     
      B007
       
      
      
     
      2
       
     
      B001
       
      
      
     
      3
       
     
      B000
       
      
      
     
      4
       
     
      B004
       
      
      
     
      5
       
     
      B003
       
      EOF;$xml = simplexml_load_string($str, "SimpleXMLElement", LIBXML_NOBLANKS);$res = $xml->xpath("/channel/item/id[text()=4]/parent::item/pd");foreach ($res as $node) {        echo $node->getName() . " " . $node->{0} . PHP_EOL;}?>