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I would encourage you to consider the odds that a web app developer will write an application that caches better than a database, and why we don't see that patt

• pavlov 9y ago
  What do you mean by "the odds"? It's quite hard to write an application that doesn't cache better than the overhead involved in hitting a database on every request (building SQL queries, waiting on the socket, marshalling the result data...) The app developer has a tremendous advantage over the database simply because she knows what the data is. Personally I find that it makes a lot of sense to think of in-memory objects and their layout first, then treat the database as a persistence solution. This was not doable in the '90s because of memory constraints, but today the cheapest cloud VM instances have more memory than what you'd get on a high-end box back then. You asked why this doesn't happen more often in practice -- I guess there is simply a lot of inertia involved. Many popular frameworks like Rails are designed around the broken stateless model and can't be reset easily. There are also large platform vendors who benefit from the low-performance solution: companies like Heroku are very happy to pretend that scaling means buying more crappy stateless server instances from them.
  • spacemanmatt 9y ago
    The odds are low. The premise that you will write a write-through cache that is faster and less buggy than say, PostgreSQL, is one I would bet my enterprise against. It is foolhardy to dismiss the labor-years invested in databases.