Have any standard to select datastore?
Comes down to if you really need High Availability and Disaster Recovery. If thats a huge must then Cassandra may be the better choice. If you are less concerned on those fronts and want a simple easy to leverage DB then PostgreSQL will be a bit easier imo, just because SQL support and management interfaces around SQL db’s in general are easier.
Does DB select have anything to do with the amount of data?
When I need create 100K consumer, JWT and so on, can postgreSQL support performance
If I need HA, Dose Cassandra must be cluster?
Postgresql will be able to support 100k consumers. Certainly seems like an excessive # of consumer accounts to me and I am not exactly sure how well Kong scales past say 10,000+ consumers but do what you have to do I suppose. I know I read a github issue where someone created 50,000 proxies on Kong and noticed due to # of sheer proxy resources added latency upwards of 2-3 seconds.
As for HA yes Cassandra would need to be clustered to achieve that. minimum 2 data centers I would say with 3 nodes in each imo.
Thank you for your response, now maybe I know what db I should select.