varnish vcl purging cache selectively

Question

So i am using varnish for the first time. i have spent quite some time reading on how it works, but i am unable to figure out how do i selectively purge the cache. like say i have a url like this ``` /?account=123&url=google.com ``` and another like ``` /?account=123&url=stackoverflow.com ``` I need to purge the cache where `account=123`. I can only figure out that issuing purge on /?account=123&url=stackoverflow.com will only purge the cache where the url matches the incoming url with PURGE method. Any help is appreciated.

Accepted Answer

So this is what works. In varnish 3 selective purge is called ban. so you need to use

```
ban("obj.http.x-url ~ " + req.url);
```

varnish vcl purging cache selectively

Solution

Problem