Partitions in Master/Child aggregator

Do Aggregators(Both master & Child) also contain partitions(Shards) similar to leaves and do they also perform query execution tasks(DML) along with leaves in addtion to aggregating results from leaves?

Only leaves contain partitions. For the most part all DML execution will run on the leaves, however, some operations will run on the aggregators at the optimizer’s discretion.

You could also take a look at https://docs.singlestore.com/v7.1/key-concepts-and-features/distributed-architecture/cluster-components/ if you want to read more.