| Question : | What's the difference between the *connect and *pconnect database functions? | |
| | Answer : | from http://www.php.net/manual/en/function.mysql-pconnect.php :
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mysql_pconnect() acts very much like mysql_connect() with two major differences.
First, when connecting, the function would first try to find a (persistent) link that's already open with the same host, username and password. If one is found, an identifier for it will be returned instead of opening a new connection.
Second, the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use (mysql_close() will not close links established by mysql_pconnect()).
These type of links is therefore called 'persistent'.
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I think that's a pretty good explanation myself.
basically, use pconnect when you're going to be using the same host a lot, but otherwise there's no real need. as Steve Yelvington said in a post a while back ():
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A persistent connection is potentially shared by serial invocations of your application ... but you don't need to know about it. If a connection already exists to the same database with the same username and password, PHP will take advantage of it automatically. If not, PHP will open such a connection and leave it open in hopes of using it again.
Now, stop and consider whether you really want to do this.
A persistent connection comes with benefits AND costs. The benefit (not having to reconnect to MySQL) comes at the cost of eating memory and -- importantly -- tying up MySQL connections.
Persistent connections make a lot of sense for a high-volume application on a Web server that has a fairly narrow purpose. Persistent connections do not make sense for low-volume applications on machines that are shared by many other applications (which probably describes your Web site on a shared host).
On a machine shared by many Web sites hitting a common MySQL server, persistent connections could backfire by locking out other users.
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