I m partitioning my problem using a Domain-Driven Design approach. Several databases arise with low or null coupling.
In the long term they will be separate databases on separate hosts, horizontally scaled. However, currently I do not need/want such an expensive deployment. I just plan to run the whole thing on a single PostgreSQL cluster. The development environment is another clear situation where having a single cluster is desirable.
Authors as Chris Richardson recommend using schemas in the near term however, I have found this implies rewriting part of the SQL code when logical replication is used to solve the couplings. I imagine he is using the term schema with MySQL in mind. https://microservices.io/patterns/data/database-per-service.html
Using separate databases seem to be the perfect solution in terms of SQL code invariance but, does this imply a performance penalty on a sole cluster compared to a single database virtually segmented by schemas?
I have read this similar question https://stackoverflow.com/questions/1152405/is-it-better-to-use-multiple-databases-with-one-schema-each-or-one-database-wit/1157008#1157008 but mine is clearly focused on performance penalty. I am clearly biased to segment the problem using databases from a logical point of view.