Re: This object is updated, how come Squid doesn't not this?

From: Jonathan Larmour <>
Date: Wed, 09 Jul 1997 21:59:11 +0100

At 22:19 09/07/97 +0200, Gerben Wierda wrote:
>I have a CERN httpd running locally. I also have a squid cache running.
>When I updated a .gif file, it turns out squid is constantly giving me the
>one from the cache, not the one from the local server:
>868436745.836 79 TCP_HIT/200 4115 GET
> - NONE/- image/gif
>Squid notices a TCP-HIT, but the file *is* modified. What is going wrong?
>When I connect directly to httpd, I get the new file allright, so it is
>squid that seems in the wrong.

I suspect you believe squid should always work in the same way as the CERN
proxy (since you have the httpd, you may have used it as a proxy). The idea
behind squid caching is to return objects that _probably_ haven't changed.
Sometimes this works, sometimes it doesn't. Have a look in the doc
directory, or the FAQ for how the decision is made as to whether an object
can still be returned or not. It uses things like the last modified time or
an expiry header (if available) to decide, along with some settings you
provide in squid.conf.

If you really want to ensure you fetch the latest version of the object
every time, then look at the refresh_pattern command in squid.conf. With
this you can ensure that an If-Modified-Since request is produced every
time. The drawback is that you always have to go to the original site to
check this - although, if it hasn't changed, you won't need to fetch the
whole object again.

Read the contents of the doc/ directory, the FAQ, and the comments in

Jonathan L.

Origin UK,323 Cambridge Science Park,Cambridge,England. Tel: +44(1223)423355
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Received on Wed Jul 09 1997 - 14:07:28 MDT

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