本文主要通過樣例代碼介紹如何使用只讀實例。

注意事項

  • 數據導入只能將數據導入主實例。
  • 通過Gremlin DSL寫數據只能將數據寫入主實例。
  • 查詢請求可以發送給主實例或只讀實例。

樣例代碼

樣例模擬社交場景，進行新增查詢、建立關系、查詢關系等操作。
  • 依賴包
    <dependency>
    <groupId>org.apache.tinkerpop</groupId>
    <artifactId>gremlin-driver</artifactId>
    <version>3.4.3</version>
</dependency>
  • 實例信息
    主實例:
host: $master_host

只讀實例1:
host: $read_host1

只讀實例2:
host: $read_host2

賬號信息：
username: $username
password: $password
  • 實例鏈接YAML文件
    • 主實例YAML文件 remote-master.yaml，用來初始化寫客戶端
      # remote-master.yaml
hosts: [$master_host]
port: $port
username: $username
password: $password
connectionPool: {
  maxSize: 16,
  maxInProcessPerConnection: 2,
  maxContentLength: 81928192
}
serializer: { 
  className: org.apache.tinkerpop.gremlin.driver.ser.GraphBinaryMessageSerializerV1 
}
    • 查詢實例YAML文件 remote-read.yaml，可配置一批GDB實例來進行查詢任務，客戶端有負載均衡功能。
      # remote-read.yaml
hosts: [$master_host,$read_host1,$read_host2]
port: $port
username: $username
password: $password
connectionPool: {
  maxSize: 48,
  maxInProcessPerConnection: 2,
  maxContentLength: 81928192
}
serializer: { 
  className: org.apache.tinkerpop.gremlin.driver.ser.GraphBinaryMessageSerializerV1 
}
  • 參考代碼
    package com.alibaba.gdb.test;

import org.apache.tinkerpop.gremlin.driver.*;

import java.io.File;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author xxx
 * @date 2021/01/19
 */
public class ReadInstance {
    private static Cluster masterCluster = null;
    private static Client  masterClient = null;

    private static Cluster readCluster = null;
    private static Client  readClient = null;

    private static final String masterYamlFile = "remote-master.yaml";
    private static final String readYamlFile = "remote-read.yaml";

    // 返回寫client
    public Client getMasterClient() throws Exception {
        if (masterClient == null) {
            File file = new File(masterYamlFile);
            masterCluster = Cluster.build(file).create();
            masterClient = masterCluster.connect().init();
        }
        return masterClient;
    }

    // 返回查詢client
    public Client getReadClient() throws Exception {
        if (readClient == null) {
            File file = new File(readYamlFile);
            readCluster = Cluster.build(file).create();
            readClient = readCluster.connect().init();
        }
        return readClient;
    }

    // 新寫入一個用戶
    public boolean addUser(String userId, String name, int age, double height, String city) throws Exception {
        String dsl = "g.addV('user').property(id, userId).property('name', name).property('age', age).property('height', height).property('city', city)";
        Map<String , Object> map = new HashMap<>();
        map.put("userId", userId);
        map.put("name", name);
        map.put("age", age);
        map.put("height", height);
        map.put("city", city);
        List<Result> resultList = getMasterClient().submit(dsl, map).all().join();
        return true;
    }

    // 新建立兩個用戶的關系
    public boolean addReleationship(String userId1, String userId2, long timeStamp) throws Exception {
        String dsl = "g.addE('friend').from(V(userId1)).to(V(userId2)).property('timeStamp', timeStamp)";
        Map<String , Object> map = new HashMap<>();
        map.put("userId1", userId1);
        map.put("userId2", userId2);
        map.put("timeStamp", timeStamp);
        List<Result> resultList = getMasterClient().submit(dsl, map).all().join();
        return true;
    }

    // 查詢某個用戶所有的好友中和自己年齡一行的好友,返回好友的信息
    public List<Result> querySameAgeFriend(String userId) throws Exception {
        String dsl = "g.V().hasId(userId).as('a').both('friend').where(eq('a')).by('age').valueMap()";
        Map<String , Object> map = new HashMap<>();
        map.put("userId", userId);
        List<Result> resultList = getReadClient().submit(dsl, map).all().join();
        return resultList;
    }

    // 查詢用戶好友的好友, 哪些還不是自己的好友,返回他們的信息
    public List<Result> query2HopFriend(String userId) throws Exception {
        String dsl = "g.V().hasId(userId).both('friend').aggregate('my_friend').both('friend').where(without('my_friend')).valueMap()";
        Map<String , Object> map = new HashMap<>();
        map.put("userId", userId);
        List<Result> resultList = getReadClient().submit(dsl, map).all().join();
        return resultList;
    }
}