
Originally Posted by
Social-Media
Google doesn't add or delete listings because of an XML sitemap anyway. Having a URL in a sitemap doesn't guarantee it will be indexed any more that NOT having a URL in the sitemap will guarantee that it is not indexed. They simply use the sitemap to "assist" during crawling of your site... i.e. to find URLs that might not be reachable through a normal crawl and MOST importantly, to give you a way to prioritze which URLs they index first.
By setting priorities in the Sitemap XML you can basically tell Google, "These URLs are MOST important, so if you have room in your index for my site, index these first. If you still have room for pages from my site then index these pages next. And if you still have room for pages from my site then index these pages next... etc.
Limiting your sitemap to the most recent 50,000 pages is not really a good idea if your site has tons of URLs. Sites like RealEstate.com have millions of URLs the majority of which would never be found by a crawler without 1) a sitemap or 2) millions of deep links.
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