[paulyg]

I agree with your assessment. To me the reason we keep ping-pnging between the two extremes is a lack of standardized and common caching mechanism. In a perfect world every web server would be behind an HTTP reverse proxy and we could just use HTTP headers to control caching. But there are a lot of quirks to that so unless you control the whole stack you don't have a proxy out front. And then you get into all other kinds of caching schemes: filesystem, memcache, redis, s3/cloudfront, etc. Which one you choose is determined by your tech stack, your PaaS, etc. Which the CMS creators have limited control over. If caching was a no brainer CMS creators could just concentrate on making the dynamic part good.

[andybak]

Agreed. Essentially SSGs are caching - or rather they are a way of pushing the caching problem down onto a lower level.

It's no different to 'clear the whole cache every time I change any content and store it all in memcached' - you're just substituting 'file-system' for 'memcached'.

Of course - SSG do solve another problem - that of needing complex software running on your server - you can run SSGs locally or on a centralized server - but that's not what is being discussed here.

[mercer]

The crucial difference, as others have pointed out, is that if you start with a dynamic site and add caching, there are a lot of likely gotchas like infinite url's that all load a slightly different page (pagination, tag combinations, etc.), as well as potential security issues when a page is not cached yet, or the cache is busted.

On the other hand, if you start with a SSG, your initial state is that every page is cached and works, and you have to think carefully of adding some kind of pagination mechanism.

As the quote goes, "There are only two hard problems in Computer Science: cache invalidation and naming things." The big benefit of a SSG is that you 'solved' the cache problem, and will immediately be aware of issues there.

[pdonis]

> It's no different to 'clear the whole cache every time I change any content and store it all in memcached' - you're just substituting 'file-system' for 'memcached'

There's no reason why the SSG needs to rebuild the entire site if you've only changed one thing.

[andybak]

True but my point still stands - some caches are dumb and some are smart. Some SSGs rebuild everything and some can figure out what needs to be rebuilt.