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Help Center/ MapReduce Service/ Developer Guide (Normal_3.x)/ ClickHouse Development Guide (Normal Mode)/ Overview/ Basic Concepts

Basic Concepts

Updated on 2022-09-14 GMT+08:00

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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

Previous topic: Introduction to ClickHouse

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