Shulou(Shulou.com)06/01 Report--

The TiDB architecture diagram is as follows

The TiDB cluster is mainly divided into three components:

TiDB Server

TiDB Server is responsible for receiving SQL requests, processing SQL-related logic, finding the TiKV address for storing data needed for calculation through PD, and interacting with TiKV.

Get the data and finally return the result. TiDB Server is stateless, does not store data itself, is only responsible for computing, can be extended infinitely horizontally, and can be extended through the

Load balancer components, such as LVS, HAProxy or F5, provide a unified access address.

/ / analogy mongos or router server in MongoDB sharding cluster

PD Server

Placement Driver (PD for short) is the management module of the whole cluster, which has three main tasks: one is to store the meta-information of the cluster (where is a Key stored?

TiKV node); second, scheduling and load balancing of TiKV clusters (such as data migration, Raft group leader migration, etc.); third, global unique allocation

And incremental transaction ID.

PD is a cluster, and an odd number of nodes need to be deployed. Generally, it is recommended to deploy at least 3 nodes online.

/ / analogy of config server in MongoDB sharding cluster

TiKV Server

TiKV Server is responsible for storing data. From an external point of view, TiKV is a distributed Key-Value storage engine that provides transactions. The basic unit for storing data is

Region, each Region is responsible for storing the data of one Key Range (the left closed and right open interval from StartKey to EndKey), each TiKV

The node is responsible for multiple Region. TiKV uses Raft protocol for replication to maintain data consistency and disaster recovery. Copies are managed in units of Region

Multiple Region on different nodes form a Raft Group, which is a copy of each other. Load balancing of data among multiple TiKV is scheduled by PD

Here, scheduling is also carried out in Region units.

/ / analogy of replica set in MongoDB sharding cluster

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