Why we’re switching to calendar versioning

This means subscribers to our release notes will see quite the jump in today’s version numbering, from last week’s 2.1.5 to today’s 19.1 beta. A couple details on the semantics of our numbering system: we’re using a two-digit year for the major component and release number within the year for the minor one. We chose release number rather than two-digit month to reduce the chance users inadvertently violate our constraint that we don’t support skipping versions for upgrades.

Source: www.cockroachlabs.com