The problem I have is - we need to process & change(update/insert) 55M Data every 2 min and this updated data to be available for Rest API for Filtering / Selection. Response time for Rest API should be less than 1 sec.
The most important factors for me are processing and storing time of 2 min. There need to be 2 views of Data One is for Selection & 2. Changed data.
By 55M do you mean 55 million entity changes per 2 minutes? It is relatively high, means almost 460k per second. If I had to choose between Scylla or Cassandra, I would opt for Scylla as it is promising better performance for simple operations. However, maybe it would be worth to consider yet another alternative technology. Take into consideration required consistency, reliability and high availability and you may realize that there are more suitable once. Rest API should not be the main driver, because you can always develop the API yourself, if not supported by given technology.
Why an issue? Is AGPL a problem for you? It only means that if you change the source code of the server you need to contribute your scylla.git changes. 99.99999% of users don't need to change a single line thus it's the same as Apache.
Licensing policy suggests `We promise that we will not seek to enforce the copyleft provisions in the AGPL v3.0`, sadly license overrules promise. AGPL as a license is not that widely used or preferred, and there are very good reasons for it.
Most companies are already doing good with Cassandra, and to jump into a new database project with a complex license the incentive, just isnt there. no matter how good the benchmarks are.