That only works for MySQL databases (SQL is a great query tool but not used in my script).
I'm talking strictly about PHP arrays.
Granted, my content system can use MySQL as a datasource but I use multiple data sources: text files for things like photog keywording and simple posts, .INI formatted files and XML for structured data , etc. (hence the beauty of my system... got the idea from Jeff Zucker's Perl DBI::AnyData but made a web content system out of it).
The commonground here is that the scriptlets return results in an multi-dim'ed array. The search feature then works on all results regardless of where the data is coming from.