Notes from the Google Webmaster Hangout on the 16th of April 2019.
Google Only Needs to Crawl Facet Pages That Include Otherwise Unlinked Products
For ecommerce sites, if Google can access and crawl all of your products through the main category page then it won’t need to crawl any of the facets. However, facets should be made crawlable if they contain products that aren’t linked to from anywhere else on the site.
New Googlebot User Agents Are Updated Within the Official Google Documentation
Googlebot user agent strings are listed in the official Google documentation and are updated fairly frequently, so if you’re getting visits that are similar to Googlebot but aren’t in the documentation, then they are likely to be fake or a user running cloud hosting. Run a reverse lookup for Google’s IP address to double check.
Having Incorrect Markup Can Cause Google to Turn Off All Structured Data For That Site in SERPs
If you implement incorrect markup, such as having specific product markup sitewide, the Web Spam or Structured Data teams could completely switch off structured data for that website from showing in the SERPs.
Event Markup Shouldn’t Be Used For Online Events
Event markup is meant for events with a physical location, and shouldn’t be used for online events like auctions or sales.
Structured Data Should Be Specific to the Primary Element of a Page
John recommends using one set of structured data which is relevant to the main content on a page, whether that’s an article or a product, for example. You can use multiple subsets of a particular structured data category, but avoid using too many different types.
Displaying Expertise on a Topic Plays a Role in Rankings
There is no quick fix for improving a site or author’s expertise on a subject, however, this is a factor that feeds into rankings. It takes time to build a presence as an authority on a topic.
A 302 Redirect is Eventually Treated as a Permanent Redirect
A 302 redirect will be treated as a permanent redirect if it is in place for a significant amount of time, regardless of its temporary status code.
Mixing 301 & 302 Redirects in a Chain Can Cause Confusion About Which URL Should be the Canonical
If Google encounters a mix of 301 and 302 redirects in a chain, it won’t receive clear signals on which URL should be indexed and shown in the search results. To decide this, it will take other canonicalization signals into account.
Make Sure Old Site Isn’t Being Blocked from Crawling During Migration
During a site migration, if the old site is being blocked from being crawled by Google in robots.txt, this can cause issues with Google being able to process the migration and pass on signals to the new site.