Q: 50,000 URLs to redirect. One-to-one mapping or pattern rules — what scales?

Q: 50,000 URLs to redirect. One-to-one mapping or pattern rules — what scales?

Nobody hand-maps 50k URLs, so the real question is how much you can safely automate.

Short answer: pattern (regex) rules for predictable structure, one-to-one only for your top pages and the exceptions.

Long answer:
If the new structure mirrors the old (just a path change like /products/ to /shop/), one regex rule handles thousands cleanly. This is the only sane approach at scale.

But patterns lie on edge cases — discontinued products, merged categories, renamed slugs. Those need explicit one-to-one redirects, and importantly your money pages deserve hand-checked targets, never a blind pattern.

The hybrid: regex for the bulk, an exceptions list (loaded first, so it wins) for everything that breaks the pattern.

Next step: write your pattern rules, then build a small priority list of top-traffic and orphaned URLs with manual targets that override the patterns.