To me it seems to be an abomination without any real purpose.
That it’s basically undocumented doesn’t really improve things. After some searching I found a bit of documentation. The real site, however, seems gone so you’ll have to be happy with google’s cached version. I guess that means I was really lucky to find that piece of information.
The page says:
Name: SQL safe mode setting
Synopsis: If the SQL Safe Mode option is enabled the MySQL and Ingres extensions will ignore the supplied host, user and password information and will use only the default ones.
Can someone please give me a use case for this? Usually safe mode is considered and enabled on machines with multiple users so why would one then want to limit everyone to the same mysql user? I can’t see any point for this.
I think it should be removed from PHP. And if not removed proper documentation should be written, just have a look at the confusion on usenet groups regarding this “feature”.