Google Search bug caused by issue with its ‘indexing systems’

On Monday we detected an issue with our indexing systems that affected Google search results. Once the issue was identified, it was promptly fixed by our Site Reliability Engineers and by now it has been mitigated.
Thank you for your patience!

— Google Webmasters (@googlewmc) August 11, 2020

The indexing system, Caffeine, does multiple things:
1. ingests fetchlogs,
2. renders and converts fetched data,
3. extracts links, meta and structured data,
4. extracts and computes some signals,
5. schedules new crawls,
6. and builds the index that is pushed to serving.

— Gary 鯨理／경리 Illyes (@methode) August 11, 2020

Don’t oversimplify search for it’s not simple at all: thousands of interconnected systems working together to provide users high quality and relevant results. Throw a grain of sand in the machinery and we have an outage like yesterday.

— Gary 鯨理／경리 Illyes (@methode) August 11, 2020