The world-wide web is built on top of many abstractions. That is what makes it powerful. As a user, we are typically just concerned with a browser and a “site”. When I first started programming for the web, I learned about HTTP, request and responses. Sometimes, one needs to dig deeper into common architecture patterns. In this article, Jonathan Fulton covers some of that architecture: DNS, load balancers, web and application servers, databases, caching. I found it to be a very useful reference. Note: As is always the case with computers, there are more levels of abstraction to learn: TCP, IP, UDP, TLS, etc.
Yorick Peterse discusses some of the scaling issues that GitLab went through and how they resolved them. I find these type of articles very enlightening. Both for the solution they chose and for those that they discarded: Your particular scaling problem might look different, making one of those solutions more attractive.
Pedro Rolo discusses how to go beyond basic queries with
Arel. I personally use techniques similar to the ones outlined in the article often. Caution:
Arel is considered private API by Rails maintainers. If you decide to use it, there might be some work needed to ensure your code works when upgrading Rails. I’ve never had a significant problem with that, provided that I have good tests around complex queries. I much prefer
Arel to using long and complicated
sql fragments as strings. I believe those are even more brittle.