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Singlestore multi node architecture components

 Singlestore multi node architecture components: 

Cluster: Cluster contains aggregator nodes and leaf nodes. Cluster is made of all nodes on which Singlestore DB is installed. 
Master Aggregator: Cluster contains one master aggregator, aggregator responsible for cluster monitoring and  failover. Master aggregator process DDL, DML, Failover, Reference Tables, CML
Child Aggregator: Cluster may have zero or more child aggregator, all it depends on query volume. The child aggregator process DML, and help master aggregator to reduce the load. 
Leaf: Cluster could have many leaves. The leaf node stores subset of data set. It could be a part of availability group when high availability is configured. 
Availability Group: It is a group of leaves - leaf nodes, stores redundant data. The purpose of availability group is to deliver high availability in case of leaf node failure. Redundancy is configurable via redundancy level. 
Master Partition: Data partition stored primarily on leaf node. 
Slave Partition: Copy of data partition from another node for high availability. 
Shard Key: Consists of 1 or 2 column of the tables. Singlestore store common shard key in same partition and node. i.e. if two tables have same shard key value these rows will be stored in a same partition on same node. 
Segment file: Columnstore data file, it is compressed. Each column of the table has its own file. Each file store 1M rows.
Sort key: Sort key is used for columnstore tables. It is clustered columnstore index.

Ref.: 

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