Copy Query Search Results to Another Index

Has anyone tried to copy search results from one index to Another. Use case here is this: Query the daily data, Aggregate it on a daily basis and copy the results to a new daily summary index.
thoughts?

Pretty much exactly what I'm trying to do - without having to read a couple of million aggregation results into an external script and re-indexing them into a new summary-index.

Did you perhaps find an elegant solution ??