I have a site with thousands of pages that need to be redirected. I was thinking of using a 301 redirect in my .htaccess, but I'm just afraid that this will be very inefficient.
Would having a .htaccess with thousands of lines (there is no way to have a re-write rule, they have to be mapped one by one), mean that every time someone accesses one of our pages, they have to read the entire .htaccess? Is that a bad thing? This sit is in a shared host.
I saw a previous answer here about using RewriteMap. How is that different than having the 301 redirects?
Thanks
For simple page redirects 301 is the best and it's very fast. RewriteMap is for more complex rewrite functions or doing very specific rewrite tasks.
Before black listing your pages server side, I would try remapping with your application first.
If you set up the redirect with .htaccess those pages will be dead to Google which of course may or may not be a bad thing. Basically once Google indexes those redirects there really is no going back (SEO).
In short redirect wisely.