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Product IntroductionBasic Concept

Basic Concepts

Region

The geographical location of the server where you purchase the cloud data warehouse UClickHouse. You can choose the Region where the UClickHouse cluster is located according to your needs.

Zone

A physically isolated area with separate power and network within the same region. Intranet communication is possible between zones, and network latency within a zone is smaller.

UClickHouse Cluster

The cloud data warehouse UClickHouse is a distributed database composed of multiple Clickhouse Server nodes. Depending on the purchased specifications, UClickHouse nodes may contain one or two replicas. A UClickHouse cluster may contain one or more shards.

Replica

To ensure data safety and high availability of cluster services, UClickHouse provides a replica mechanism that redundantly stores data from a single-node server on two or more servers.

  • Double Replica: Each node contains two replicas. When one replica service is unavailable, another replica of the same shard can continue to provide service.
  • Single Replica: Each node has only one replica; when this replica is unavailable, the entire cluster becomes unavailable.
Note:
  1. The double replica mode has high availability features. Every two replica nodes form a shard, and when one node within the shard is unavailable, the other node can continue to provide service capability (requires using the replica table engine).
  2. The single replica mode does not commit to SLA and is recommended only for test/development environments. For production environments, the double replica mode is recommended.

Shard

In scenarios with ultra-large scale data, the storage and computing resources of a single machine become a bottleneck for data processing and analysis. UClickHouse disperses the massive data across multiple servers (nodes). Each server (node) only stores and processes a portion of the massive data. In single replica mode, a shard corresponds to a node. In double replica mode, a shard corresponds to two nodes. Each server (node) is referred to as a shard.

Compute Specifications

The resource configuration of the UClickHouse cluster. You can choose any of the two specifications to create, according to your needs.

Application ScenariosUsage Restrictions