New ask Hacker News story: Ask HN: Best practices for technical SEO for domains with more than 100k pages?

Ask HN: Best practices for technical SEO for domains with more than 100k pages?
2 by brntsllvn | 3 comments on Hacker News.
By "technical SEO" I mean SEO problems that require software development. What's special about domains with 100,000+ pages (e.g. niche search engines and large e-commerce sites) is that most basic SEO advice is necessary but far from sufficient. I'm on a project with 1,000,000 pages and only about 50,000 are indexed. My "crawl budget" is absolutely small, but relatively large. How do I make sure the "right" content gets indexed? How does Google even define "right"? I seem to be writing a lot of code to answer basic question like "which of my 1,000,000 pages are indexed?" and "which pages should I be actively seeking to index and de-index?" If you work on "technical SEO" for something like Stack Overflow or Amazon I'd love to learn from you. And if these are the wrong questions to ask, I'd especially like to learn from you.