[Mod_gzip] "mod_gzip_send_vary=Yes" disables caching on IE? (1.3.26.1a)

[Robert Collins]

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On Tue, 2002-12-10 at 09:43, TOKILEY@aol.com wrote:

> Robert...
>=20
> I don't mean to harp on this issue but it IS partially relevant
> since we are just trying to really understand the REALITIES
> of caching here and not the 'urban legends'.

Sure.
=20
> I have another (quick) question for you regarding this "Expires: -1"
> thing.
>=20
> If SQUID does, in fact, actually CACHE a response that is
> showing up with "Expires: -1" in the response headers
> ( which means it cannot possibly EVER be 'fresh' )...

Yep.

> ...then when in the heck does such a response ever
> get REMOVED from the cache ( erased from disk ) ?

This depends on your cache policy, and on future responses.
it will be ejected (removed/erased) when any one of the following
occurs:
1) On validation, an object with a different strong or weak validator
arrives. (for example, a different last-modified datestamp).
2) The replacement policy for that cache directory ejects it. (i.e. for
the LRU (Least Recently Used) replacement policy, this object has not
been served to a client for the longest period of all objects in the
same cache directory (see squid.conf - cache_dir) AND more space is
needed. Squid has several replacement policies, and a stable API for
writing more, so the logic here depends 100% on your install of squid.
3) Someone chooses to purge it.
=20
> If it was already STALE when it arrived... then how can
> it ever get MORE STALE and when would SQUID=20
> purge this puppy from the disk?
>=20
> Are all of these "Expires: -1" documents hanging around
> forever in SQUID caches?

They hang around as long as they can save bandwidth :}. See above for
the exact conditions.

Rob


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