Invalidate just one page under a location directive

Server NGINX
#1

Hi all,

A section of my virtual(say /industry) is cached with

proxy_cache_key $scheme$host$request_uri;

key. This will cache all pages under this virtual. I do cache
invalidation
by firing a request with

proxy_cache_bypass

Now if I need to invalidate cache for a page under this virtual, how
should
I go about doing it?

Say /industry is the location directive

I need to invalidate just

/industry/category/cars

How do I do this?

-Quintin

#2

On Wednesday 08 February 2012 11:44:04 Quintin P. wrote:

The best way would be to create a location for this particular page:

location /industry/category/cars {
…
}

http://nginx.org/en/docs/http/ngx_http_core_module.html#location

also, you can utilize the map directive functionality, e.g:

map $uri $is_cached_uri {
default 1;
/industry/category/cars 0;
}

proxy_cache_bypass $is_cached_uri;

http://wiki.nginx.org/HttpMapModule

wbr, Valentin V. Bartenev

#3

Thanks would be difficult because my intention is to maintain per page
cache. So we are talking about 1000+ pages and more being created
dynamically.

-Quintin

2012/2/8 Валентин Бартенев [email protected]

#4

On Wednesday 08 February 2012 13:36:31 Quintin P. wrote:

Thanks would be difficult because my intention is to maintain per page
cache. So we are talking about 1000+ pages and more being created
dynamically.

Probably, I misunderstood. My solution switches cache off completely for
particular uri.

Maybe this module is useful for you:
http://labs.frickle.com/nginx_ngx_cache_purge/

wbr, Valentin V. Bartenev

#5

08 февраля 2012, 13:37 от Quintin P. : > Thanks would be difficult
because my intention is to maintain per page > cache. So we are talking
about 1000+ pages and more being created > dynamically. > > -Quintin > >
2012/2/8 Валентин Бартенев > > > On Wednesday 08 February 2012 11:44:04
Quintin P. wrote: > > > Hi all, > > > > > > A section of my virtual(say
/industry) is cached with > > > > > > proxy_cache_key
$scheme$host$request_uri; > > > > > > key. This will cache all pages
under this virtual. I do cache > > invalidation > > > by firing a
request with > > > > > > proxy_cache_bypass > > > > > > Now if I need to
invalidate cache for a page under this virtual, how > > should > > > I
go about doing it? > > > > > > Say /industry is the location directive >

I need to invalidate just > > > > > > /industry/category/cars

How do I do this? Do you want to do per-request cache
invalidation based on client information (header values, cookies,
originating IP etc.), so the cache is bypassed whenever a client sends a
request that matches your cache invalidation criteria, or do you want to
be able to invalidate a certain URI for all future clients and requests
by sending some kind of “switch caching off for this URI” request? Max

#6

Simples way to say this would be, invalidate proxy_cache_key but not all
of
the cache.

#7

I was hoping for a solution from the vanilla builds

#8

Can someone help? My small site on a tiny VM is being bombarded and the
cache invalidation is clearing up everything. Which means warming up the
caching takes a lot of expensive queries.

-Quintin

#9

On 8 Fev 2012 15h59 WET, [email protected] wrote:

Can someone help? My small site on a tiny VM is being bombarded and
the cache invalidation is clearing up everything. Which means
warming up the caching takes a lot of expensive queries.

What cache invalidation? What caching strategy are you using?
Are working with a content based expiration logic or from a
microcaching perspective?

You can inspect the cache using a small shell script:

https://github.com/perusio/nginx-cache-inspector

— appa

#10

I don’t think I made that clear.

To put it simply, Invalidate cache for a particular key entry but not
all
of the cache

e.g for

location = /vehicles {

proxy_cache_key $request_uri;

}

Hashtable for cache:

[

hittp://jj.com/vehicles/cars => hittp://jj.com/vehicles/cars

hittp://jj.com/vehicles/bus => hittp://jj.com/vehicles/bus

hittp://jj.com/vehicles/bike=> hittp://jj.com/vehicles/bike

]

I should be able to invalidate just cars because my page for cars have
changed but not others.

Hope you got the point.

Quintin

#11

Invalidate a cache page using the bypass mechanism proxy_cache_bypass,
not
expiration

To put it simply, Invalidate cache for a particular key entry but not
all
of the cache

e.g for

location = /vehicles {

proxy_cache_key $request_uri;

}

Hashtable for cache:

[

http://jj.com/vehicles/cars => cached page for cars

http://jj.com/vehicles/bus => cached page for bus

http://jj.com/vehicles/bike=> cached page for bike

  • 10,000 key, values
    ]

I should be able to invalidate just “cars” because my page for cars have
changed but not others. Say a person added a comment in the cars page.
Another analogy is to invalidate cache for a single blog post when all
the
blog posts have been cached under a single location directive.
-Quintin

#12

Thanks Antonio.

Great deal of help.

Looking into the wiki I see

“The following response headers flag a response as uncacheable unless
they
are ignored
http://wiki.nginx.org/HttpProxyModule#proxy_ignore_headers:

Set-Cookie

Cache-Control containing “no-cache”, “no-store”, “private”, or a
“max-age”
with a non-numeric or 0 value

Expires with a time in the past

X-Accel-Expires: 0“

This also means that if I send a curl call from my backend with a
Cache-Control : max-age=1, then the corresponding request/page in cache
will get invalidated the next second.

X-Accel-Expires also does the same thing I suppose. That solves my
dilemma.

-Quintin

#13

On 8 Fev 2012 16h22 WET, [email protected] wrote:

Invalidate a cache page using the bypass mechanism
proxy_cache_bypass, not expiration

IMHO the best option would be from the application side send a
‘X-Accel-Expires: 0’ header. But this needs to be done at the app
level.

Unless you place something in the headers that the application returns
Nginx there’s no way of Nginx to know what is going on.

To put it simply, Invalidate cache for a particular key entry but
not all of the cache

[

http://jj.com/vehicles/cars => cached page for cars

http://jj.com/vehicles/bus => cached page for bus

http://jj.com/vehicles/bike=> cached page for bike

  • 10,000 key, values
    ]

I should be able to invalidate just “cars” because my page for cars
have changed but not others. Say a person added a comment in the
cars page. Another analogy is to invalidate cache for a single blog
post when all the blog posts have been cached under a single
location directive. -Quintin

Send a ‘X-Accel-Expires: 0’ header from the application at:

http://jj.com/vehicles/cars

— appa