Architecture En

Overview

Pika is an open-source high-performance persistent NoSQL product, compatible with the Redis protocol, with data persistently stored in the RocksDB storage engine. It has two operating modes: Classic mode and Sharding mode.

• Classic mode: A 1-master-N-slave synchronization mode. One master instance stores all the data; N slave instances fully mirror-sync the master's data. Each instance supports multiple DBs. DBs start from 0 by default, and the databases configuration item controls the maximum number of DBs. A DB's physical form on Pika is a file directory.
• Sharding mode: In Sharding mode, the user's stored data collection is called a Table. Each Table is split into multiple shards, each called a Slot. For a given KEY, the hash algorithm determines which Slot it belongs to. All Slots and their replicas are distributed across all Pika instances according to a certain strategy, with each Pika instance holding some primary Slots and some slave Slots. In Sharding mode, the master/slave relationship is at the Slot level rather than the Pika instance level. A Slot's physical form on Pika is a file directory.

Pika's operating mode can be configured via the instance-mode configuration item in the configuration file, setting it to classic or sharding.

1. Classic (Master-Slave) Mode

2. Sharding Mode