When we create an xml sitemap for a site with dynamic data, should we prepend all new data to the start of the sitemap OR append it to the end? Do search engines hate it when a sitemap is 100% different each time OR when they see that it's mainly the same, but just a bit different at the end.

###Example

Lets imagine we're creating an XML sitemap for StackOverflow -> a site with dynamic data.

Lets also assume that, ever day we have 1000 new 'items' to get added to the sitemap and we start out with 200,000 items.

I'm also generating the sitemap every hour or every day... don't really care just yet.

Now, with all these items to be sitemap'd, first I'll need to have a sitemap index that points to each page of items to get indexed. Kewl.

If I add the new items to the START of the list of items to get indexed, then each 'page' in the index will be different, compared to the previous time the search engine grabbed the sitemap index.

eg.

• Day 1: Page1 will have 100 items, with the most recent item having a timestamp of 1pm, day1.
• Day 2: page1 will now have a complete new set of 100 items, with the timestamp of the newest item in this page being 1pm day2.

This also means every other page, in the index is different to the previous.

So does this mean the search engine would need to go through EACH PAGE again to see what resources it needs to index? But at least all the new content is first, so the assumption here is that the search engine will be indexing the newest stuff, first.

As opposed to ..

appending any new data to the end of a sitemap ..

• Day 1: Page1 has 100 items. most recent is timestampe 1pm, day1
• Day 2: Page1 is still identical to page1, the day before. Now, page 22 has the most recent stuff, which didn't exist the day before.

Here i'm assuming the search engine will see all of this stuff and say 'ahh! most of these pages haven't changed since i was last here .. so i'll ignore them .. but lets see AH! there's a few new pages that DO have some new data.. so lets check them out instead'.

Anyone have any experience with this?

When we create an XML sitemap for a site with dynamic data, should we prepend all new data to the start of the sitemap OR append it to the end? Do search engines hate it when a sitemap is 100 % different each time OR when they see that it's mainly the same, but just a bit different at the end?

Example

Let's imagine we're creating an XML sitemap for Stack Overflow → a site with dynamic data.

Let's also assume that, ever day we have 1000 new 'items' to get added to the sitemap and we start out with 200,000 items.

I'm also generating the sitemap every hour or every day, don't really care just yet.

Now, with all these items to be sitemap'd, first I'll need to have a sitemap index that points to each page of items to get indexed. Kewl.

If I add the new items to the START of the list of items to get indexed, then each 'page' in the index will be different, compared to the previous time the search engine grabbed the sitemap index.

For example:

• Day 1: Page1 will have 100 items, with the most recent item having a timestamp of 1pm, day1.
• Day 2: page1 will now have a complete new set of 100 items, with the timestamp of the newest item in this page being 1pm day2.

This also means every other page, in the index is different to the previous.

So does this mean the search engine would need to go through EACH PAGE again to see what resources it needs to index? But at least all the new content is first, so the assumption here is that the search engine will be indexing the newest stuff, first.

As opposed to …

appending any new data to the end of a sitemap …

• Day 1: Page1 has 100 items. most recent is timestampe 1pm, day1
• Day 2: Page1 is still identical to page1, the day before. Now, page 22 has the most recent stuff, which didn't exist the day before.

Here I'm assuming the search engine will see all of this stuff and say 'ahh! most of these pages haven't changed since I was last here … so I'll ignore them … but let's see AH! there's a few new pages that DO have some new data … so let's check them out instead'.

Anyone have any experience with this?