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Re: querystring part of cache key

From: Adrian Chadd <adrian@creative.net.au>
Date: Sat, 23 May 2009 00:45:38 +0800
To: David Morris <dwm@xpasc.com>
Cc: Jamie Lokier <jamie@shareable.org>, Adrien de Croy <adrien@qbik.com>, HTTP Working Group <ietf-http-wg@w3.org>
Message-ID: <20090522164538.GH21660@skywalker.creative.net.au>
.. Squid just caches based on the URL (with relevant rules controlling
whether the URL can be cached or not.)

I wrote some extensions to allow an external plugin to "normalise"
a URL before caching. People use this to cache things like Youtube.



On Fri, May 22, 2009, David Morris wrote:
> On Fri, 22 May 2009, Jamie Lokier wrote:
> >Adrien de Croy wrote:
> >>
> >>there were discussions recently about the method being part of the cache
> >>key, since the response for different methods on the same URI could
> >>presumably be cacheable and different.
> >>
> >>What about query string?  If the result to something that has a
> >>querystring is marked as cachable by the origin server, then is it
> >>deemed part of the URI for the cache key?  I'd presume yes.
> >
> >Of coures, the query string is just part of the URI.
> >
> >>Since URIs can be arbitrarily long, yet database fields aren't good with
> >>this, I'd presume it's common practise to look up based on some hash
> >>value.  Is this approach used?  Is there any industry-standard hashing
> >>method, e.g. MD5 of method+URI(normalised) + querystring ?
> >
> >I doubt it.  Why would you do that?  I don't think it's normal to use
> >a URI to select an application and pass the querystring verbatim to a
> >database, or at least it's not a good idea :-)
> Why not? .. this is a caching related question where the URI is part of
> the cache key ... since I've not implemented such a cache, I can't speak 
> to what I have done, but a hash such as MD5 seems reasonable ... in 
> particular if followed by an exact match comparison with a value stored
> in a blob, etc.

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Received on Friday, 22 May 2009 16:46:19 UTC

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