[Trace] Storage-Query

[hanahmily]

The query sub-system of the storage module ingests query request from the liaison, and then attempts to

• find the most efficient way to execute it based on internal statistics and data placement.
• generate a series of tiny operations and compose them to a hierarchical execution topology.
• send operations to storage and index modules to retrieve desired results.
• aggregate sub results to a final one, then transfer to liaison module.

Before diving into the codes, we need to output a more fined design of this module.

[lujiajing1126]

Pls assign to me

[lujiajing1126]

@hanahmily a preliminary draft can be found here
https://docs.google.com/document/d/1BHIcHby_aEplVbsDv2mUFnu_nSpx_upAGHL96sTY_U8/edit?usp=sharing

[hanahmily]

This module is done