More work.

Change-Id: I6266e684b2da7fae9d5625b44bacf7ea8d3c6394
Make existing tests pass.

Change-Id: Ie64213c008628bfd0465707f7fc19d0a5b17668d
Load chunkDescs on demand during first query.

Change-Id: Id133c742d4eb19de1f1c1f3a49972ee2ea054e0a