In place upgrades across major versions - support large columnstore deployment upgrades

5.6.2 -> 23.02.x
Customers on prem with large deployments of columnstore can NOT afford exporting and importing data from columnstore to upgrade major versions. In one specific case, exporting their 20TB of compressed data is estimated to take over 25 days and consume 60-80TB uncompressed.

The ask is to mature the product with a migration script/tool that can bridge the engineering deltas from one version to the next. be it the extent map or data files to enable in place upgrades to be supported, certified and work.