Will an incomplete google sitemap hurt my search ranking?

Question

If I submit a sitemap.xml which does not contain all of the pages of my site, will this affect my search ranking?

For example: If my sitemap only contained pages that had been created in the last month and didn't include all the pages from the past year, would Google treat these missing pages differently?

Answer 1

No. Google has stated that it WILL index pages that aren't included in the sitemap and that sitemaps themselves have no bearing on ranking, only page discoverability.

Answer 2

There will most likely be a difference, but it's not certain that the pages excluded from the site map will get a lower status than without a site map.

The Google bot limits the time that it spends indexing a site. It will start with the most obvious pages and work it's way down, until it reaches a set limit were it will stop looking.

By adding a site map you will make it easier for the bot to find the most relevant pages. When the bot is done with those, it will continue with the rest of the pages. Possibly it will have more time left for the rest of the site if the site map made the first part of the work more efficient.