PHP连接的更好方法（实时或即时）

Question

I use mysqli functions (forgive me for not using PDO) to connect to MySQL Databases. I was wondering which of these is a better approach?

1. Keeping connection alive on all classes and close the connection at the end of the php script. I mean, not closing $link till the footer.
2. Opening a new Connection on every classes and closing them instantly when done.

Please consider both resources and security. Thanks! :)

Answer 1

Well there are multiple answers to this question around. I think the reason that makes php developers still can't make a good decision around closing or keeping alive, is the connection pool concept (well documented) in the other programming languages. For example JDBC driver, does not take care of pooling itself, But some other wrappers libraries, take care of that and create pooling. Pooling means keep reasonable connections alive for some times, and use it for new query requests. If all the alive connections are busy, start a new one and also don't close that, because it sounds the application is having .

According to this ( http://www.percona.com/blog/2006/11/12/are-php-persistent-connections-evil/ ), mysqli connections are not keep-alive by default. Meaning as soon as the query is finished, it gets closed by the mysql itself (after a little time wait). Despite that, the default time wait for keeping alive, is about 8 hours in mysql and also is configurable.

My conclusion is: It is not only harmless to keep some connections open and reuse them, but also it is recommended. But should handle something like the session scope variables and such things and also a piece of recommendation is: Its better to find an uptodate wrapper or api to handle the pooling than getting your hands greasy.