Multiple Cache Object for same file

[Maxim Dounin]

Hello!

On Thu, Jul 02, 2020 at 05:06:17AM -0400, anish10dec wrote:

> We are observing that multiple cache object is getting created for same file
> in Nginx Cache which is resulting into non optimal use of cache storage.
> 
> We are using proxy_cache_key as $uri. 
> 
> proxy_cache_key         $uri;
> 
> For example with file having URI
> /content/entry/jiomags/content/719/51/51_t_0.jpg
> 
> 2 cache object has been created in cache folder. Both the files are having
> same KEY
> 
> -rw------- 1 nginx nginx 21023 Jun 27 16:11
> ./2/95/9d78505da184e6ccd981fefe6b333952
> -rw------- 1 nginx nginx 21023 Jun 27 18:16
> ./f/ad/c8e1c56031a14dd4a27e538956253adf
> 
>  vi ./2/95/9d78505da184e6ccd981fefe6b333952

[...]

> Vary: Accept-Encoding^M

[...]

> What could be the reason for duplicate file getting cached having same URI
> and KEY.
> Please help

The reason is the "Vary: Accept-Encoding" header line returned by 
your backend.  If you want nginx to ignore it, consider using 
"proxy_ignore_headers Vary;", see 
http://nginx.org/r/proxy_ignore_headers for details.

-- 
Maxim Dounin
http://mdounin.ru/