Help Center> MapReduce Service> Developer Guide (Normal_3.x)> ClickHouse Development Guide (Security Mode)> Overview> Basic Concepts
Updated on 2023-08-31 GMT+08:00
View PDF

Basic Concepts

Concepts

  • cluster

    Cluster: Cluster is a logical concept in ClickHouse. It can be defined by users as required, which is different from the general understanding of cluster. Multiple ClickHouse nodes are loosely coupled and exist independently.

  • shards

    Shard: A shard is a horizontal division of a cluster. A cluster can consist of multiple shards.

  • replicas

    Replica: One shard can contain multiple replicas.

  • partition

    Partition: A partition is used for local replicas and can be considered as a vertical division.

  • MergeTree

    ClickHouse has a huge table engine system. As the basic table engine of the family system, MergeTree provides functions such as data partitioning, primary indexes, and secondary indexes. When creating a table, you need to specify the table engine. Different table engines determine the final character of a data table, for example, the features of a data table, the form how data is stored, and how data is loaded.

Parent topic: Overview