Re: Some data related to the frequency of cache-busting
Benjamin Franz (snowhare@netimages.com)
Thu, 28 Nov 1996 07:21:40 -0800 (PST)
On Wed, 27 Nov 1996, Jeffrey Mogul wrote:
> Anyway, the results are
> Responses with no last-modified time: 10401
> Responses pre-expired: 28
> for a total of 10429 cache-busted refs, with these byte-counts:
> 3932702 req-bytes, 81597623 resp-bytes, 85530325 bytes
>
> As a fraction of all 61108 references, this is
> 17% of the references
> 21% of the req-bytes, 25% of the resp-bytes, 25% of the total bytes
>
> As a fraction of the 33589 non-query possibly-cachable references:
> 31% of the references
> 38% of the req-bytes, 30% of the resp-bytes, 30% of the total bytes
>
> Summary: while it is certainly debatable whether my categorization
> of no-Last-Modified responses as "cache-busted" is appropriate or not,
> if one accepts this categorization, then the frequency of cache-busting
> seems to be pretty high. One could also debate how much this would
> be reduced by our hit-metering proposal, but there does seem to be
> some potential here.
You pegged my primary objection to your methodology. It is entirely
unsupportable to label having no last-modified as being deliberate
cache-busting (the only kind of cache busting this proposal could affect).
Pretty much all CGI does this (no last-modified) by default:
from www.netimages.com:
GET /ni-cgi-bin/fetch HTTP/1.0
HTTP/1.0 200 OK
Date: Thu, 28 Nov 1996 15:03:19 GMT
Server: Apache/1.1.1
Content-type: text/html
Set-Cookie: Apache=19830833849193398884; path=/
I made absolutely no effort to intentionally cache bust the response (the
data served is static - but from a huge database of Usenet articles). In
fact - I wrote it well before I knew *how* to deliberately cache bust.