They’re for teams that still refuse a proper RDBMS but desire an Apache-level of infrastructure complexity.
They are using CitusDB but it's still RDBMS and support most PostgreSQL SQL query without the need to rewrite your query or change your schema.
I dont know if they are still using Vitess or migrated to Google other relational Database "Spanner"
In general I've noticed that people outside Google assume that Spanner is much more popular than it really is.
if you work at google and its one of the option to choose from! Is there any reason to "not" choose spanner for new project and instead use something else?
Meanwhile I'm over here using Scylla and 3 nodes can give me roughly 3.5M TPS for data extraction.
RDBMS are great for certain use cases but they do not scale and if you think they do you don't really know what scale means.
Sure you can cite things like Github using MySql, but i'll also point out they've invested thousands upon thousands of man hours customizing layers on top of MySql to support their sharding which also, oops, had a bug that gave them almost half a day of downtime at one point. This is not a good use of someone's time, GH definitely made the wrong decision. Don't steer other people into making similar mistakes especially given it seems you have a lack of experience on designing systems at scale.
Clickhouse vastly outperforms and outscales Scylla with a fraction of the hardware and cost.
Should I have simply said "SQL databases where data is represented in tables with a defined schema" to simplify the discussion and prevent your ignorant diatribe?
Have you used any of these technologies? Cassandra/Scylla have a defined schema. Did you really not know that?
Any of the above makes your data accessible via standard SQL. You can hire and utilize proficient data analysts, not people writing esoteric queries in whatever flavor of NoSQL, while actually solving business needs.
How are Scylla / Cassandra better?