Using htaccess to "fake" an XML file?

Here's the problem I'm trying to solve: I have a dynamic php-driven website that is constantly being updated with new content, and I want my XML sitemap to stay up to date automatically. Two options I see:

1. Write a php script that queries my database to get all my content and outputs to http://mysite.com/sitemap.xml, execute the script regularly using a cron job.
2. Simply create my sitemap as a php file (sitemap.php), query the db and write directly to that file, and use the htaccess rewrite rule RewriteRule ^sitemap.xml$ sitemap.php so that whenever someone requests sitemap.xml they're directed to the php file and get a fresh sitemap file.

I'd much rather go wi开发者_运维技巧th option #2 since it's simpler and doesn't require setting up a cron, but I'm wondering if Googlebot will not recognize sitemap.xml as valid if it's actually a php file?

Does anyone know if option #2 would work, and if not whether there's some better way to automatically create an up-to-date sitemap.xml file? I'm really surprised how much trouble I've had with this... Thanks!

Just make sure your script generates the appropriate Content-Type header. You can do so with header().

Google will only get the headers and the body of the response. If your php script returns the same headers and the same body as your webserver would return, then there is technically no difference between the PHP script response or the XML file response by your server. Use curl -i http://example.com/ to inspect the response headers of a request if you would like to test that on your own.

So you can safely do this, that's for what mod_rewrite has been designed (next to the many other things).