This topic describes the terms of ApsaraDB for Redis to help you better understand and use Redis databases.
Term | Description |
instance ID | A basic unit of ApsaraDB for Redis. Each instance corresponds to a user space. Redis has limits on instance configurations, such as the number of connections, bandwidth, and CPU power. These limits vary based on different instance types. You can view the list of your instance IDs in the console. |
node | The smallest building block of a Redis deployment. Redis nodes usually run on Elastic Compute Service (ECS) instances. Nodes are categorized into data nodes and proxy nodes based on their roles and functionalities.
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shard | Each Redis cluster instance is composed of multiple shards. The architecture of each shard within a Redis cluster instance varies based on the instance type. If the instance type is High Availability, each shard consists of master and replica nodes. For example, if the specification of a cluster instance is 8 GB Cluster (4 Shards, 2 GB per Shard) and the instance type is High Availability, the cluster instance consists of four shards, and each shard contains master and replica nodes. |
deployment model |
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version compatibility | Tair is compatible with open source Redis versions such as Redis 7.0, Redis 6.0, Redis 5.0, and Redis 4.0. |
eviction policy | The eviction policy that is used in Tair is the same as that of open source Redis. For more information, see Key eviction. |
database (DB) | Each Redis instance can contain up to 256 databases: DB 0 to DB 255. By default, data is written to DB 0. |