The behaviour of these functions is affected by settings in php.ini.
| Name | Default | Changeable | Changelog | 
|---|---|---|---|
| msql.allow_persistent | "1" | PHP_INI_ALL | |
| msql.max_persistent | "-1" | PHP_INI_ALL | |
| msql.max_links | "-1" | PHP_INI_ALL | 
Here's a short explanation of the configuration directives.