Up until recently, I have viewed the query cache as a very important tool to improve query performance. Today, I was listening to a podcast that discussed tuning the query cache to 0, and using a better memory caching solution (such as memcache.d).
But they also mentioned that there are a few cases in which query_cache is helpful. So a general recommendation would be to have it enabled to on-demand (using
SELECT SQL_CACHE, with a query_cache_type = 2 config setting).
My question is, assuming you've got a caching solution like memcache.d in place, what type of circumstances would make the query_cache more optimal?
Edit: added link