Q:

Nginx Alias vs Rewrite

I have two working configurations that, on the surface, seem to do the same thing. They both accomplish the functionality that I need:
location ~ ^/(css|images|js)/ {
    location ~ '^/(css|js)/[0-9]{8}-(.*)$' {
        alias /$1/$2;
    }
    root /server/path/to/web/root;
}

AND
location ~ ^/(css|images|js)/ {
    rewrite '^/(css|js)/[0-9]{8}-(.*)$' /$1/$2 break;
    root /server/path/to/web/root;
}

They both take a URL like /css/87654321-styles.css and deliver the file /css/styles.css. I lean toward the second solution because it's more succinct, but I don't know if one is better than the other for performance reasons, unintended side-effects, etc.
Here's my original SO post, for reference/context.
After being directed to the documentation for the Nginx rewrite module, I found these interesting lines:

The ngx_http_rewrite_module module directives are processed in the following order:

the directives of this module specified on the server level are executed sequentially;
repeatedly:
  
  
a location is searched based on a request URI;
the directives of this module specified inside the found location are executed sequentially;
the loop is repeated if a request URI was rewritten, but not more than 10 times.

So, if I used the rewrite directive without the break flag, there could be at least one additional loop of the server level directive.

A:

alias is like root, so you need to use full server path
you can add break flag to rewrite for avoid internal redirect. added without break rewrite will make loop (internal redirect) for process all locations again; but break tell to rewrite do not loop and run current location.

I don't think here big difference in performance. Main difference is changing internal request uri. But in case of static files serve both work well.

