Joining two Indices in Lucene

[Gimantha Bandara]

Hi,

I am now looking into BlockJoinQuery where I can join two indices and
execute search queries. My concern is this... Is it possible to perform
"AND" and "OR" operations between two seperate indices? As an example, I
have a common field "_id" in both indices. I will relate the two indices(
using "fromField and toField"). Lets say field "title" is only in the first
index and field "ISBN" is in 2nd index. I would like to get the unique
"_id" values where "title:SOME_VALUE" AND "ISBN:SOME_OTHER_VALUE" . Is this
possible?

Thanks,
Gimantha