Is it possible to query multiple indices?

[Alireza Noori]

I have multiple collection of data. Each one is updated with different intervals. I was wondering whether I can index each one to a different index and then when I'm running a query, use them all. If this runs exactly like the regular query process, I'm guessing this would help me get far better performance.

If it's possible, please tell me how. I want to use the source code (rather than using the compiled .jar). So please, tell me how to do it via Java code.

Thanks in advance.