Debating the Value of <lastmod> and <priority> in Sitemaps: Worth Keeping or Useless?

The Best Of

Jul 21, 2023, 7:49 AM

Does anybody have opinions about <lastmod> and <priority> in sitemaps? Most I've ever heard is people saying they're useless, but do you still keep them there just because "why not?"? And do other search engines use them in any capacity we're aware of?

Forwarded thread from another channel:

Valentin Pletzer

Jul 21, 2023, 7:55 AM

I would argue that priority is useless but lastMod is not. I believe if you have a lot of pages and you use lastMod correctly this does help a lot.

By correctly I mean: only change the date/time if the main content changed but not fluff like navigation etc

Also you should use lastMod correctly within the index sitemap. Only change lastMod in the index sitemap if something changed in the corresponding sitemap

Kyle Faber

Jul 21, 2023, 7:55 AM

priority is not used by google.

lastmod should be used, but authentically.

what i mean by "authentically" is that it should match the actual last time the URL was updated (e.g. do not update the lastmod each day as the sitemap is updated).

the direction given by google is to update the lastmod on significant changes (e.g. do not update if you correct a word misspelling. DO update it if you add a new section of content, or update for the year, etc.)

if you update the lastmod date, and the published/modified date on the content (or diff between crawls) does not consistently match, google will start to trust your sitemaps less.

Boris Kuslitskiy

Jul 21, 2023, 7:57 AM

Oh, oh, fun thing I found recently when auditing a site. Every lastmod was the same, and it was set for one day in the future. Probably a timezone issue, but hilarious to see.

Kyle Faber

Jul 21, 2023, 7:58 AM

i've seen that too!

Valentin Pletzer

Jul 21, 2023, 7:59 AM

Here in Germany someone had found a case were a news publisher published old articles (before 1970) which resulted in Google ignoring the articles alltogether ????

Boris Kuslitskiy

Jul 21, 2023, 8:00 AM

Hahahahaha. That's amazing. Nothing existed before 1970, so that makes sense.

Adam Di Frisco

Jul 21, 2023, 8:01 AM

So if you're working e-commerce, for example, would you avoid automatically-refreshed sitemap generators to avoid constant lastmod changes?

Boris Kuslitskiy

Jul 21, 2023, 8:02 AM

Eh... is the alternative doing it manually?

Kyle Faber

Jul 21, 2023, 8:02 AM

You can and should update the sitemaps daily, just don’t change the lastmod on the URLs within them if they were not updated

Boris Kuslitskiy

Jul 21, 2023, 8:02 AM

As far as I know, Google doesn't penalize you for spamming lastmod, it just ignores the values.

Kyle Faber

Jul 21, 2023, 8:03 AM

So some URLs will have and older lastmod date, and others will be newer

Boris Kuslitskiy

Jul 21, 2023, 8:04 AM

@kyle, not every sitemap generator is going to be able to look at when pages were actually last modified.

Kyle Faber

Jul 21, 2023, 8:19 AM

@boris.kuslitskiy that’s a separate topic and not relevant to the original question ☺️

Mike Blazer

Jul 21, 2023, 9:37 AM

@pletzer what if you changed something else, not the main content, but let's say hreflang setup? Why not change lastmod date so Google would see the changes?

What if there are new phat comments added to the page?

I would update the lastmod.

Valentin Pletzer

Jul 21, 2023, 9:50 AM

@seo901 you are right and @kyle had probably the better wording. Let me rephrase: You should change the lastMod if something significant changes. But this usually leads people to change the lastMod more than needed. So significant should be: bigger content changes, meta data changes that need a quick recrawl, significant changes in the internal linking …

Kyle Faber

Jul 21, 2023, 11:32 AM

here's the quote on how they handle it from their :

> Google uses the `<lastmod>` value if it's _*consistently*_ and _*verifiably*_ (for example by comparing to the last modification of the page) _*accurate*_.

what i've been trying to give is just what google has stated within their docs; i think as we wish (@softplus was cited on this topic as well - John, please let me know if i'm misrepresenting what you said in that context).

so if we think we should update it based on modifying hreflang, changing internal links, etc., then that's totally our prerogative to do so.

however, if your ducks aren't in a row for how you do that (e.g. matching lastmod to the dateModified schema, or something like that per the note above), then it's possible that it may be ignored. whether that has a substantial impact on your site one way or the other is unknown and likely largely dependent on your site.

Alex Harford

Jul 25, 2023, 4:39 AM

100% with Kyle on this one. To add to it, if <lastmod> can't be accurate for whatever reason, I recommend leaving it out. Especially when there are tens of thousands of URLs in a sitemap, it can make a significant difference to file size.