* Lazy load chunks for queries.

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

* Add context to the lazy chunk calls

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

* Make sure labels are plumbed through

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

* Pre-load non-overlapping chunk iterators

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

* Review feedback

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>