Outputcache - how to determine optimal value for duration?

I read somewhere that for a hig开发者_运维问答h traffic site (I guess that is a murky term as well), 30 - 60 seconds is a good value. Obviously I could do a load test and vary the values, but I couldn't find any kind of documentation on this. Most samples have a minute, a couple of minutes. There's no recommended range. Is there something on msdn or anywhere that talks about this?

This all depends on whether or not the content changes frequently. For slowly or non-mutating content, a longer value works perfectly. However, you may need to shorten the value for always-changing data or risk bad output.

It all depends on how often a user requests your resource, and how big the resource is.

First, it is important to understand that when you cache something, that resource will remain the same until the cache duration runs out. A short duration cache will tax the webserver more than longer one, but the short will provide more up-to-date data should the requested resource change.

Obviously you want to cache database queries as much as possible, prioritizing those who are called often. But all cache takes memory on the server, and as resources runs low the cache will be evicted. Take this into consideration when caching large things for longer durations.

If you want data on how often users requests a resource you can use Google Analytics, which is extremely easy to set up.

For very exhausitive analytics you can use Kiwik. It requires a local server though.

On very changing resources, don't cache at all, unless it's really really resource heavy and isn't vital to be realtime updated.

To give you an exact number or recommendation would be to make you a disservice, there are too many variables around.