Given the power and flexibility of mod_rewrite it's not surprising that people often use it as their golden hammer. Part of gaining knowledge about mod_rewrite is knowing when not to use it.
The following is a list of misuses of mod_rewrite and more appropriate (and often faster) alternatives. These examples assume the RewriteRules are not placed in a directory context (i.e., not in a .htaccess file nor in a <Directory> section).
Simple Redirects
RewriteRule ^/(.*) http://other.example.com/$1 # is better expressed as.. Redirect / http://other.example.com/
Complex Redirects
# redirect and drop the trailing uri RewriteRule ^/.* http://other.example.com/ # is better expressed as.. (we only need to match every possible string # without storing it, thus just ^) RedirectMatch ^ http://other.example.com/
# redirect to a uri containing a portion of the original RewriteRule ^/foo/(.+)/bar http://other.example.com/$1 # is better expressed as.. RedirectMatch ^/foo/(.+)/bar http://other.example.com/$1
Appropriate uses of mod_rewrite for redirecting include:
- Redirecting based on the query string
- Redirecting based on other request details such as user-agent.
Aliasing
RewriteRule ^/foo/(.*) /bar/$1 # is better expressed as.. Alias /foo /var/www/bar
or
RewriteRule ^/foo/(.*)/baz /bar/$1 # is better expressed as.. AliasMatch /foo/(.*)/baz /var/www/bar/$1
Appropriate uses of mod_rewrite for aliasing include:
- Aliasing based on complex rules
TODO, validate AliasMatch example, add more valid uses or expand them 
Proxying
RewriteRule ^/(.*) http://other.example.com/$1 [P] # is better expressed as.. ProxyPass / http://other.example.com/
# reverse proxy everything except images
RewriteCond %{REQUEST_URI} !^/images
RewriteRule ^/(.*) http://other.example.com/$1 [P]
# is better expressed as..
ProxyPass /images !
ProxyPass / http://other.example.com/