[Mod_gzip] Issues with 1.3.26.1a: TIFF corrupted (if excluded) and 'Go Back' broken on Win98

[Glenn]

On Thu, Jan 30, 2003 at 10:52:20AM +0100, Tomaz Borstnar wrote:
> At 10:34 30.1.2003 +0200, Keith Waters wrote the following message:
> >Hi - Yesterday I tried upgrading mod_gzip from 1.3.19.1a  to 1.3.26.1a , 
> >but
> >hit two problems
> 
> 
> 
> >I downgraded back to 1.3.19 this morning and now all is back to "normal".
> 
> One of those Vary problems.  Few of us had to downgrade because of major 
> TRAFFIC increase - hits went from 12 million to over 50 million and things 
> werent really any faster because images were fetched for every page view - 
> even with Back button!

It's a known problem that this version of mod_gzip is a bit over-zealous
in generating Vary headers, sometimes when it doesn't need to do so.  My
workaround is to have absolutely no mod_gzip_item_exclude lines.  That's
right: none.  And I only have a single mod_gzip_item_include line:

    ## minimal included set of items to compress to avoid sending Vary * header
    ## This is very conservative and cooperates superbly with mod_expires
    ## caching headers.  (Netscape 4.0[678] will still have problems, but it
    ## only affects a fraction of a percent of hits (about 0.00015 == 0.015%)
    ## on our site with the settings below)
    mod_gzip_item_include           uri   \.s?html?$

This compresses most *.html *.htm *.shtml *.shtm files and results in
simple Vary headers only on those files.  (And no Vary: User-Agent headers)

Cheers,
Glenn