File searching in a lot of directories..

[Anon]

I have a lot of different files in one folder (about 5.000) how to put them in directories (may be a lot of them for example 1000 or 2000 directories) and

I HAVE TO WRITE FUNCTION that will automaticly know where to search (in which directory) for file... and as a result I should get name of this directory.... how to do it...

Directory names and other are not important... what is important is that it (this function) should be faster than database select...

I don't have a clue how to do it... A friend of mine suggested checksums and stuff but I don't know how they work and how to use them in such a function.

THX for all kind of help...