Nice job, then! Technical downtime that’s virtually undetectable to users is a big win. In fact, “less than 5 seconds of downtime” in the title would actually make me want to read the article more as I tend to be suspicious of “zero downtime” claims for database upgrades, whereas <5s is clearly almost as good as zero and actually quantified :)

On the other than "less than 5 seconds of downtime" might give the impression that new queries sent within that time period would be rejected, while zero implies this doesn't happen, i.e. that it's undistinguishable from normal operation for the client.

And being even more precise in the title would just make it less titley :).

Yeah - a quantifiable amount in the headline would change the likelihood of the article being taken seriously - it goes from "No downtime? I call BS" to "Less than 5 seconds, that seems reasonable, and worth investigating"

Less than 5 seconds seems pretty reasonable to me to call it zero down time.

5 seconds pause on queries would make our app server drop connections and throw errors under cyclical high load - which would result in a incident.