About the new sitemap format
With the release of version 4 of the sitemaps plugin, the type of the generated sitemap changed from a single sitemap file to a sitemap-index file with sub-sitemaps.
The old sitemap format
The old sitemap looked like the following table. It included all the content of your blog in a single file.
The new sitemap format
The new sitemap format looks like the following table. Instead of including all content in one huge file, the sitemap index-file links to several sub-sitemaps as described in the official Sitemaps Protocol. For each content-type (Posts, Pages, Custom Post Types, Taxonomies) there is a sub-sitemap, for some of them (posts) there is one for each month. The actual sub-sitemaps look like the old format showed above.
What are the benefits?
- The required resources on server-side are lower. Instead of generating a huge sitemap, which required a lot of memory and CPU, only small pieces are served on request. That avoids any memory errors or capacity problems on the server.
- Your sitemap can contain more content. Each sitemap is limited in size and the number of URLs inside. Splitting the sitemap up means there is more room for your posts.
- The sitemap loads faster. Since the sub-sitemaps are much smaller than the huge old sitemap, they obviously load faster.
- Less traffic. The search engines can see when the sub-sitemaps have been modified, so they can request only the ones which have changed.
- Do i need to submit each sub-sitemap to Google? No, the plugin will automatically tell Google about the index file. Google handles the sub-sitemaps automatically!
- Will the new sitemap format hurt my rankings? No, why should that happen? The new format is an official sitemap format defined by Google. In fact, Google is using the new format for their own blogs! XML Sitemap of Google Webmaster Blog
- For some reason, I don’t like the new format. Can I change to the old one?. There is not really a reason to not use the new format, but if you really don’t like it, you can use the 3.x version of the plugin!