Why metrics indexes in Hour and Day precisions stop update after upgrade to 7.x?

This is an expected case when 6.x->7.x upgrade. Read Downsampling Data Packing feature of the ElasticSearch storage.

The users could simply delete all expired *-day_xxxxx and *-hour_xxxxx(xxxxx is a timestamp) indexes. SkyWalking is using metrics name-xxxxx and metrics name-month_xxxxx indexes only.