Support secondary indexes on tenant-specific tables

[elilevine]

Support secondary indexes on tenant-specific tables by:

• creating index on tenant-specific table by inserting indexed columns after the tenant_id and type_id columns, but before the entity_id column either:
  • in the same underlying HBase physical table, but with a different type_id for the index table. We'd need to be careful when querying the data by filtering out index rows, as they would not conform to the data table row key.
  • have another separate physical HBase table that stores all index rows. In this case, the same type_id could be used for the index and data table. Probably simplest to create this separate physical HBase table upfront, when the base data table is created.

Probably the latter approach is better/easier. We could also have different table/column family configurations for the index table which is probably good.

@elilevine - what do you think?