Minimize memory consumption in dashboard

Memory consumption optimized from 2.7G down to 1.5G on full dataset:
 * Record index is not necessary in runtime storage since it it
   needed for update operations only
 * Store compact records as tuples instead of dicts

Co-author: Yuriy Taraday <yorik.sar@gmail.com>

Change-Id: I9a361e9373b5ed4fada527959a604cf09a02e5b9
Merge "Minimize memory consumption in dashboard"