Stack Overflow runs what is essentially a monolithic architecture. Though they do have a few services, it isn't what I would describe as a micro-service architecture.
Monzo (UK bank) has 1600+ microservices, but mandates a common framework/library and uses Cassandra. (Which is basically a shared nothing, bring your own schema "database".)
So it makes sense to combine advantages of different approaches.
using non-ACID db for financial services probably requires lots of trickery.
it is web scale though
Re:Postgres scaling advice
by throwdbaaway on Tuesday January 26, 2021 @06:06PM
(#25922099)
Upvoted, but I am not sure tokopedia is even in the top 10 in Asia.
Also, the fascination with GMV tends to make it looks like high scalability is required. In another HN discussion, someone mentioned about running the database for an ecommerce that had 1 billions GMV a few years back. Assuming a conservative $5 per order, that translates to about 6 orders per second on average.
However not only driven by DB performance, but also on organizing hundreds of engineers they adapted microservice architecture. Then they slowly migrating to per domain specific DB, it is just classic microservice migration story.
While single DB may bring us pretty long way, designing the system into more discipline logical domain level segregation will help when there's need to move to microservice.
*looks like HN reader quite sensitive with microservice migration comment, usually this kind of comment got down voted easily.