sitemapindex

A sitemapindex is an XML document used to list multiple sitemap files for a large website, as defined by the sitemaps.org protocol. It acts as a directory that helps search engines discover all relevant sitemaps in one place.

The root element of a sitemapindex is sitemapindex, and it contains multiple sitemap entries. Each entry includes a loc element with the URL of a sitemap file and an optional lastmod element indicating the last modification date of that sitemap. This structure enables organized aggregation of sitemaps for complex sites.

Sitemap indexes are used to manage scenarios where a site exceeds the limits of a single sitemap. A crawler fetches the sitemapindex URL, reads the listed sitemaps, and then follows their loc references to retrieve the pages listed in those sitemaps. This approach improves crawl efficiency and ensures coverage of large or frequently updated sites.

Limits and deployment considerations include that a sitemapindex can list up to 50,000 sitemap entries. Each referenced sitemap may contain up to 50,000 URLs and should be under 50 MB when uncompressed. Compressing large sitemaps with gzip is common, and ensuring that all references are publicly accessible is important for reliable crawling. The sitemapindex should be placed at a well-known URL, typically at the site root or at /sitemap_index.xml.

Example:

<?xml version="1.0" encoding="UTF-8"?>

<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">

<sitemap>

<loc>https://www.example.com/sitemap-pages.xml</loc>

<lastmod>2024-12-01</lastmod>

</sitemap>

<sitemap>

<loc>https://www.example.com/sitemap-blogs.xml</loc>

<lastmod>2024-12-02</lastmod>

</sitemap>

</sitemapindex>