What is the search index and why is a value of "1" too low?

[Gutspiller]

So I added this hack that advises you on settings that it has a problem with. It says that my search value of 1 is too low. Why?

I use my forums as a massive database for game news. I would like it when people search for doom 3, it doesn't give some crap about "3" is too small of a value, any other way around this?

How big can a search index get with this set to 1? Do I need to rebuild my search index more often or something?

[filburt1]

It should be no lower than 3 because otherwise your search index will be huge (I think I included this description in the hack).