In many database deployments, upgrades and downgrades are painpoints, as they require an outage. For this reason, the ability to perform online upgrades and downgrades is one of the important features of MySQL NDB Cluster. Online upgrades and downgrades are supported both for patch release changes (for example 7.5.4 to 7.5.5) as well as for major version changes (for example 7.4.13 to 7.5.4). From a technical perspective, there is little difference between an upgrade and a downgrade, ...