# Coordinator

## 1. Data Structure
![Coordinator Data Structure](../../images/CoordinatoreDataStructure.png)

Coordinator mainly maintains 6 main Maps:
- IdEpochMap: Save all Map epochs, and all instance ids (coordinator, store, schema, table)
- CoordinatorMap:Save all Coordinators information and state
- StoreMap: Save information and state of all Stores
- RegionMap: The most important Map, which saves the information and status of all Regions
- SchemaMap & TableMap: Save the information of schema and table respectively. For table, the mapping relationship of table→region is saved

## 2. Code Modules
![Coordinator Modules](../../images/CoordinatorModules.png)

- MetaService: Database Schema and Table related services, use server_location
- CoordinatorService: For services related to cluster management, use server_location
- NodeService: The service for querying node information in the cluster, using raft_location
- RaftService: Raft data synchronization service, using raft_location

## 3. Start Process
![Coordinator Start Process](../../images/CoordinatorStartProcess.png)