Hi, As we discussed in the sync up meeting, I come up with a draft for secondary index support. Draft<https://docs.google.com/document/d/1E1ofBQoKRnX04bWT3utgyHQGaHZoelgXosk_UNsTUuQ/edit?usp=sharing>. It is WIP. Detailed API design is not included in this version.
Thanks! Miao
