Re: [squid-users] how often should squid send If-Modified-Since: requests for a given resource?

On 15.06.06 11:05, Chris Lightfoot wrote:
> I have squid running as an accelerator in front of a site
> certain of whose pages generate Last-Modified: headers and
> respond to If-Modified-Since: conditional GETs. When
> viewing such a page through the accelerator, squid will
> send an IMS: request to the back-end on each page view,
> even if it is less than one second since the last such
> request was sent.

I think that's 100% correct. DO those pages have Expires: header?

> Is this the expected behaviour? It seems a bit pointless,
> given that the resolution of date in the headers is only
> 1s, so if the most recent version of the object squid has
> cached has Last-Modified: during the current second,
> there's no chance that an IMS: request is going to get a
> different version of it.

note that object can change at _any_ time, new object may be here within
microsecond. and since the time on server may be different, you never know
in which one microsecond the time changes :)

> (I appreciate, by the way, that this is all completely
> broken anyway, because the underlying pages may change
> more than one per second and this mechanism won't spot
> that. But that's life.)

if that makes such big problem, just use header
"Cache-Control: no-cache, must-revalidate" and don't care about caching.
(or, send page if it changed in last second, no matter what does IMS say)

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