PHP database class's multiple includes

[narekm]

Hi there.
I am developing an application in which I am using AJAX and PHP. Lets say from my initial.php files I am making request via AJAX to ajaxResponse.php file where I execute some code and interact with MySQL .Since I am handling with dtabase I am using my written Db class and on the top of my ajaxResponse.php I have to write

require_once("includes/Db.php");
    $db=new Db();

in order to use the methods of the class. I can send request to that files 1000 and more times (since I am building a livechat) and in all times it will do that require_once and $db=... . Do you think thats the best solution ? What disadvantages it has ? And what other methods you suggest to sort that out So i'll require only once or maybe anything else that you will recommend .

Thank you in advance for your efforts !!!

[pritaeas]

I don't think there is much else you can do, except for maybe caching your results somehow (if possible).

[mschroeder]

This is why ajax and php are ill suited for a real-time chat solution. Because it has to make a new request every n seconds which means you're hitting the system fresh every time since php does not really maintain state between requests.

You would really want to look at Comet
http://en.wikipedia.org/wiki/Comet_(programming)
http://ajaxian.com/archives/comet-with-php

Or, implement some form of long-polling
http://blog.perplexedlabs.com/2009/05/04/php-jquery-ajax-javascript-long-polling/

[narekm]

My application is not gonna appear online since its an experiment task so no worries about ajax and php not well suitness. And thanks for your replies. By the way I think I found a solution to my problem : SINGLETONE PATTERN