Thanks for sharing! I'm curious as to your approach to changing the ORDER BY key for such large tables without significant downtime, since AFAIK this can't be done in place (see: https://kb.altinity.com/altinity-kb-schema-design/change-ord...). Are you able to share any details?
* Create a new version of the table with the new ORDER BY.
* Create a materialized view that will insert from the old table to the new table.
* Update your application code to query the new table.
* Start inserting data into the new table.