Re: [squid-users] acceleration mode question

On Tue, 2006-08-08 at 15:56 -0400, Robert Borkowski wrote:
> Is your squid built with the --enable-x-accelerator-vary option? If
> so, do your webservers set the X-Accelerator-Vary header?
>
> This feature is used to store different copies of an object based on
> request header. For example, our webservers reply with:
> X-Accelerator-Vary: Accept-Encoding

Yes, but so does Vary. No point in activating X-Accelerator-Vary for
this when Vary does the job both better and following standards.

The purpose of X-Accelerator-Vary is only when there is parameters of
the request that you want the accelerator to account for, but not
downstream caches.

In nearly all setups this header is best left ignored. It's only
relevant to very specific setups. You'll most likely know that you need
support for the X-Accelerator-Vary when you need it, but most likely
will not have a clue what to use it for before then... (I implemented
it, but actually only have vague ideas of suitable applications)

> some browsers set accept-encoding to "gzip, deflate", while some set
> it to "gzip,deflate" (no space), and this results in two different
> objects for the same URL

Right.. Slight but harmless error in how Squid processes Vary responses.
With 2.6 the situation is improved, but still there will be some
redundant metadata in such cases.

In terms of HTTP the two is semantically equivalent as Accept-Encoding
is a list header..

Regards
Henrik
Received on Wed Aug 09 2006 - 08:26:10 MDT