MetaChunk logic issue

[KimballCai]

In this version, MetaChunk will be continuously expanded by Cubelets. However, the MetaChunk in each cubelet should only contain the necessary information for its own storage, and we can add another storage to store the global information.

For example, In Cubelet 1, the age range is 0 to 20. (in MetaChunk: 0-20) In Cubelet 2, the age range is 30 to 50. (in MetaChunk: 0-50)

we should change it into In Cubelet 1, the age range is 0 to 20. (in MetaChunk: 0-20) In Cubelet 2, the age range is 30 to 50. (in MetaChunk: 30-50) (in MetaChunk: 0-50 [global] )

In this way, we can skip several cubelets by checking the MetaChunk when we process cohort queries. For example, we can skip the search process in Cubelet 1 if the query is only about the users whose age is bigger than 30.

[KimballCai]

have fixed this issue in the pr #75