On Sun, May 20, 2012 at 12:57 AM, Amos Jeffries <squid3@xxxxxxxxxxxxx> wrote: > On 20/05/2012 4:52 p.m., Beto Moreno wrote: >> >> Hi. >> >> I have read in the doc that squid default setup is using the old way >> to handle dynamic content: >> >> case A >> hierarchy_stoplist cgi-bin ? >> acl QUERY urlpath_regex cgi-bin \? >> cache deny QUERY >> >> And for the new way for this is using the next settings: >> case B >> refresh_pattern -i (/cgi-bin/|\?) 0 0% 0 >> refresh_pattern . 0 20% 4320 >> >> Some sites I had seen they use things like: >> case C >> refresh_pattern -i (/cgi-bin/|\?) 0 0% 0 >> refresh_pattern -i \.index.(html|htm)$ 1440 90% 40320 >> refresh_pattern -i \.(html|htm|css|js)$ 1440 90% 40320 >> refresh_pattern . 0 20% 4320 >> >> the old way in your experience is no longer the right way for this? > > > There is no right/wrong here. > > HTTP/1.0 specification is clear that dynamic content created by CGI scripts > is *very likely* unsafe to cache *unless* the script emits Cache-Control > headers. > > The "old" way was to simply not cache anything which came from a dynamic > script generator. > > The refresh_pattern rules are only used for the objects which have no > cache-control (ie the unsafe requests) and "-i (/cgi-bin/|\?) 0 0% 0" is a > heuristic rule crafted specifically to match the "dynamic content" criteria > and prevent that unsafe content being cached. > > The new way permits caching whenever the dynamic responses created by modern > script languages send cache-controls. All the modern dynamic websites are > cacheable (their script engines emit cache-control) and using "?, so the old > way would prevent caching. Leaving ISP with <20% cache HIT ratios. Moving to > the new rule gains a few % in HIT ratio without much risk. > > >> What is the different between case B and case C? >> which is better? > > > There is no "better". Everything in refresh_pattern is relative to the > specific traffic pattern going through a specific proxy. > > You can tune it perfectly for todays traffic, and a new website becomes > popular tomorrow that uses entirely different patterns. Or the popular > website you are trying to cache changes their headers. > > > >> for dynamic content is the only settings we have?(I don't care about >> youtube or streaming). > > > The thing to understand is that to squid there is no distinction between > "dynamic" and "static" content. It is all just content. *individual* objects > have headers (or not) which indicate its *individual* cacheability. > > "refresh_pattern" directive is a blunt-object regex pattern applied > universally to all requests to estimate cacheability time for objects which > have no specific mention of lifetime sent by the server. > "cache" directive is a sledge hammer to prevent caching or particular ACL > matching requests. > > > >> >> exist a formula to setup min/max percent? > > > No. They are the *input* values to a formula for calculating expiry time. > They are how long *you want* to store any object which matches the regex. > > > Amos Thanks for your great explanation, I'm working on this settings and see which of them give more from my cache, thanks again!!!
