Aggregation Operations In A Distributed Database

A distributed database that includes multiple database instances receives a data-query that includes an aggregation clause on a first column of a table. The table is partitioned into shards according to a sharding criterion based on the first column such that all rows having the same value for the first column are included in the same shard. The shards are distributed to the multiple database instances. Respective intermediate results are received from at least some of the database instances. Each intermediate result received from a respective database instance that includes a respective shard aggregates values of the first column in the respective shard. The respective intermediate results are combined to obtain a final result of the data-query. The final result is then output.