Ask HN: Must knows and resources for intermediate DBAs?

I'm currently working on becoming a better database developer, and I realized that I'm not fully aware of what the core concepts behind them should be. The reason why I want to gather a solid set of resources for this topic is because I just recently ran across use-the-index-luke.com, which does an excellent job at explaining the concepts behind B-tree indexes and the subtleties involved in working with them. I was hoping that there might be equally extensive and exhaustive resources out there (they can be (e-)books you have to pay for, although free is always welcome) for other topics, such as: - creating schema that's performant and not too nightmarish to extend/maintain - scale - migrations - minimizing downtime for a running system when modifying the schema - performance optimization - understand no-sql and when to use it (actually I know the answer to this one: "7 databases in 7 weeks" by Pragmatic Bookshelf claims to answer that question) - ... whatever else is imporatnt I'm absolutely confident that you could write books on any of these topics, however the level of depth I'm interested is purely pragmatic: whatever a good developer needs to know to get the most bang for his buck and no time spent on the more esoteric fine-tuning. Any recommendations? Online resources that worked great for you? Books? If RDBMS flavor matters, let's assume I'm talking about PostgreSQL. Thanks!