Google's John Mueller answered a question I never heard before around dynamically generated sitemap files, generating new file names for these sitemap files every single day. In short, their CMS will produce a new set of sitemap files on a daily basis and the file name for those sitemap files will contain today's date. So domain.com/sitemap-A-20180205.xml and so on.
John Mueller said it is not a great idea to dynamically change your sitemap file names daily because it creates more work for Google to not only discover the new URLs in those sitemap files but also to try to find those new sitemap files.
John recommends for existing sitemap files with existing URLs keep those sitemap file names static and the same. If you need to make new sitemap files for new sections and new URLs, you can do that but try to keep the existing ones the same.
John said this at the 3:30 mark into the video:
Someone asked about file names for sitemaps and you said the file name or I think you said the filenames shouldn't be that important or shouldn't matter.Answer:
But we're seeing a situation now where we're generating sitemaps generating over a thousand individual XML sitemaps for this massive website. And the file names change every day because the date is included in the file name structure. So could that be problematic since Googlebot may not even see all these file names every day they might not know which ones they crawled which ones they did. And then we're moving it over to the next day. They say that index file references them each day so GoogleBot would know where to find these. But should we try and keep a static file name rather than having dynamic ones each day?
Yeah, I generally tend towards having a static sitemap file or mostly so that these URLs try to remain in the same sitemap files. So unless you're generating new content every day, or that amount of new content, then I try to keep the same sitemaps.
Well we are, its vehicle inventory.Answer:
Well if the the URLs are changing every day, if you have new content every day, then of course you have to generate new sitemap files. But if you have existing content in existing your sitemap files, I try to keep those as stable as possible. Just so that we can recrawl those sitemaps files as quickly as possible to really kind of keep up with the changes rather than like spending time crawling sitemap files that don't exist anymore.
Forum discussion at Twitter.