I've thought about it, and I have no time to really do a meta-search during evaluation. What I need to do is to create a single core that contains both of my data sets, and then describe the architecture that would be required to do blended results, with liberal estimates.
>From the perspective of evaluation, I need to understand whether any of the solutions to better ranking in the absence of global IDF have been explored? I suspect that one could retrieve a much larger than N set of results from a set of shards, re-score in some way that doesn't require IDF, e.g. storing both results in the same priority queue and *re-scoring* before *re-ranking*. The other way to do this would be to have a custom SearchHandler that works differently - it performs the query, retries all results deemed relevant by another engine, adds them to the Lucene index, and then performs the query again in the standard way. This would be quite slow, but perhaps useful as a way to evaluate my method. I still welcome any suggestions on how such a SearchHandler could be implemented.
