Another story of something I saw in the field which surprised me. Turns out recovery_prefetch can cause outages. Something which has been happening quietly in the background all the time, but we didn’t notice until we looked close enough to see it. After a lot of work I discovered this was partly a case where someone had dropped an email to the postgres hackers list years ago “hey what about this” and everyone thought “nah it can’t be that bad” … and now here we are seeing production outages! Ex...