cache empties itself?
Michael S. Fischer
michael at dynamine.net
Thu Apr 3 21:45:25 CEST 2008
On Thu, Apr 3, 2008 at 11:53 AM, Ricardo Newbery <ric at digitalmarbles.com> wrote:
> On Apr 3, 2008, at 11:04 AM, Michael S. Fischer wrote:
> > On Thu, Apr 3, 2008 at 10:58 AM, Sascha Ottolski <ottolski at web.de> wrote:
> > > and I don't wan't upstream caches or browsers to cache that long, only
> > > varnish, so setting headers doesn't seem to fit.
> > >
> > Why not? Just curious. If it's truly cachable content, it seems as
> > though it would make sense (both for your performance and your
> > bandwidth outlays) to let browsers cache.
> Can't speak for the OP but a common use case is where you want an
> aggressive cache but still need to retain the ability to purge the cache
> when content changes. As far as I know, there are only two ways to do this
> without contaminating downstream caches with potentially stale content...
> via special treatment in the varnish config (which is what the OP is trying
> to do) or using a special header that only your varnish instance will
> recognize (like Surrogate-Control, which as far as I know Varnish does not
> support out-of-the-box but Squid3 does).
Seems to me that this is rather brittle and error-prone.
- If a particular resource is truly dynamic, then it should not be
cachable at all.
- If a particular resource can be considered static (i.e. cachable),
yet updateable, then it is *far* safer to version your URLs, as you
have zero control over intermediate proxies.
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