[jmaker]

Depends on your requirements. If your config complexity is getting beyond manageable, the benefit of something more reliable is apparent. Type safety clears lots of common bugs no test suite would be certain to filter out. How complex should your tests get? Do you want to take on that responsibility or rather delegate it to something that provides you certain guarantees? It’s all very subjective in the end.

I run my configs mostly as YAML in Consul and Vault, sometimes in Spring Cloud Config with a git backend. This way I have dynamic config evolution. But I prefer to generate those yaml files from Dhall to avoid unnecessary bugs. After years with Haskell, the syntax is very natural, too.

As for Postgres internals, they do matter if your data set keeps growing.

Xkcd covered standardization. YAML and JSON ASTs are graphs, YAML not necessarily a tree. JSON extensions also support references. As for the ops side, YAML has become a de facto standard, HCL is used with the HashiCorp tools. Nix has its own language.

It’s not about how it’s represented but how you express dependencies across config key nodes. It’s good to avoid repetition and have a syntax linter, a compiler even better. Small static configs are amenable to querying and writing. But you need to separate the writing from the querying the configs. With Dhall you write code to generate the actual config, whether as a Dhall AST or exported to YAML or JSON, with certain correctness guarantees upfront.