citus real-time 分析demo（ 来自官方文档）

 

citus 对于多租户以及实时应用的开发都是比较好的，官方也提供了demo

参考项目 https://github.com/rongfengliang/citus-hasuar-graphql

环境准备

• docker-compose 文件

version: '2.1'

services:
  graphql-engine:
    image: hasura/graphql-engine:v1.0.0-alpha26
    ports:
    - "8080:8080"
    command: >
      /bin/sh -c "
      graphql-engine --database-url postgres://postgres@master/postgres serve --enable-console;
      "
  master:
    container_name: "${COMPOSE_PROJECT_NAME:-citus}_master"
    image: 'citusdata/citus:7.5.1'
    ports: ["${MASTER_EXTERNAL_PORT:-5432}:5432"]
    labels: ['com.citusdata.role=Master']
  worker:
    image: 'citusdata/citus:7.5.1'
    labels: ['com.citusdata.role=Worker']
    ports:
    - "5433:5432"
    depends_on: { manager: { condition: service_healthy } }
  manager:
    container_name: "${COMPOSE_PROJECT_NAME:-citus}_manager"
    image: 'citusdata/membership-manager:0.2.0'
    volumes: ['/var/run/docker.sock:/var/run/docker.sock']
    depends_on: { master: { condition: service_healthy } }

• 数据准备

curl https://examples.citusdata.com/tutorial/users.csv > users.csv
curl https://examples.citusdata.com/tutorial/events.csv > events.csv

• 数据表床架吗

CREATE TABLE github_events
(
    event_id bigint,
    event_type text,
    event_public boolean,
    repo_id bigint,
    payload jsonb,
    repo jsonb,
    user_id bigint,
    org jsonb,
    created_at timestamp
);

CREATE TABLE github_users
(
    user_id bigint,
    url text,
    login text,
    avatar_url text,
    gravatar_id text,
    display_login text
);

• 添加索引以及分布式表

CREATE INDEX event_type_index ON github_events (event_type);
CREATE INDEX payload_index ON github_events USING GIN (payload jsonb_path_ops);

SELECT create_distributed_table('github_users', 'user_id');
SELECT create_distributed_table('github_events', 'user_id');

• 导入数据

  使用psql copy，注意文件目录

copy github_users from 'users.csv' with csv
copy github_events from 'events.csv' with csv

运行查询

• 查询总数

select count(*) from github_users;

• 根据event 类似类型，分析每分钟的push event commit 数

SELECT date_trunc('minute', created_at) AS minute,
       sum((payload->>'distinct_size')::int) AS num_commits
FROM github_events
WHERE event_type = 'PushEvent'
GROUP BY minute
ORDER BY minute;

• 数据join 查询,top 10

SELECT login, count(*)
FROM github_events ge
JOIN github_users gu
ON ge.user_id = gu.user_id
WHERE event_type = 'CreateEvent' AND payload @> '{"ref_type": "repository"}'
GROUP BY login
ORDER BY count(*) DESC LIMIT 10;

graphql 集成

• 添加graphql 支持

• 一个时间分组view

create view commitdataview as 
SELECT date_trunc('minute', created_at) AS minute,
       sum((payload->>'distinct_size')::int) AS num_commits
FROM github_events
WHERE event_type = 'PushEvent'
GROUP BY minute
ORDER BY minute;

• graphql 查询

query {
  github_users(limit:10,where:{
    user_id:{
      _eq:331
    }
  }) {
    user_id
    gravatar_id
    login
    display_login
  }
  commitdataview(limit:10,order_by:{
    num_commits:desc
  }) {
    num_commits
    minute

  }
}

• 效果

说明

核心就是基于时间的数据聚合分析，处理

参考资料

https://docs.citusdata.com/en/v7.5/get_started/tutorial_realtime_analytics.html
https://github.com/rongfengliang/citus-hasuar-graphql