US Patent 11526473 Database upgrade in a distributed database cluster

A database is selected from a plurality of databases included in the distributed database cluster. A shard map of the database is acquired, wherein the shard map includes a distribution of a plurality of shards on the plurality of nodes, and one or more nodes of the plurality of nodes each includes at least one shard of an old version of the database to be upgraded to a new version. A sustainable serviceability of the database corresponding to each of the one or more nodes is predicted according to the shard map based on the assumption that the at least one shard of each of the one or more nodes has been upgraded from the old version to the new version.