RethinkDB - goddes4/python-study-wiki GitHub Wiki

When is RethinkDB a good choice?

RethinkDB is a great choice when your applications could benefit from realtime feeds to your data.

• Collaborative web and mobile apps
• Streaming analytics apps
• Multiplayer games
• Realtime marketplaces
• Connected devices

When is RethinkDB not a good choice?

• RethinkDB is not a good choice if you need full ACID support or strong schema enforcement—in this case you are better off using a relational database such as MySQL or PostgreSQL.
• If you are doing deep, computationally-intensive analytics you are better off using a system like Hadoop or a column-oriented store like Vertica.
• In some cases RethinkDB trades off write availability in favor of data consistency. If high write availability is critical and you don’t mind dealing with conflicts you may be better off with a Dynamo-style system like Riak.

Install and Run

Install the server (Ubuntu)

source /etc/lsb-release && echo "deb http://download.rethinkdb.com/apt $DISTRIB_CODENAME main" | sudo tee /etc/apt/sources.list.d/rethinkdb.list
wget -qO- http://download.rethinkdb.com/apt/pubkey.gpg | sudo apt-key add -
sudo apt-get update
sudo apt-get install rethinkdb

Install the python driver

pip install rethinkdb

Start the server

$ rethinkdb
info: Creating directory /home/user/rethinkdb_data
info: Listening for intracluster connections on port 29015
info: Listening for client driver connections on port 28015
info: Listening for administrative HTTP connections on port 8080
info: Server ready

Multiple RethinkDB instances on a single machine

클러스터 구성이 이루어지면,

1. 브라우저를 이용하여 localhost:8080 또는 localhost:8081 에 접속해 서버 현황을 볼 수 있다.
2. 클라이언트는 localhost:28015 또는 localhost:28016 에 연결하여 명령을 실행할 수 있다.

$ rethinkdb --port-offset 1 --directory rethinkdb_data2 --join localhost:29015
info: Creating directory /home/user/rethinkdb_data2
info: Listening for intracluster connections on port 29016
info: Attempting connection to 1 peer...
info: Connected to server "Chaosknight" e6bfec5c-861e-4a8c-8eed-604cc124b714
info: Listening for client driver connections on port 28016
info: Listening for administrative HTTP connections on port 8081
info: Server ready

A RethinkDB cluster using multiple machines

first machine

$ rethinkdb --bind all

second machine

$ rethinkdb --join IP_OF_FIRST_MACHINE:29015 --bind all

주요 옵션

• --bind all : 서버가 바인딩할 아이피 주소
• --http-port 8081 : 웹 관리자 페이지 포트
• --port-offset 1 : 단일 물리 서버에서 다중 인스턴스를 실행할 경우 포트가 겹치지 않기 위해 증가하는 포트 값
• --directory rethinkdb_data2 : rethinkdb 가 사용할 디렉토리 지정 (다른 인스턴스와 겹치면 안됨)
• --join localhost:29015 : 새로운 인스턴스가 합류를 시도할 기존 인스턴스 주소

---

RethinkDB Guide in python

Import the driver

import rethinkdb as r

Open a connection

conn = r.connect('localhost', 28015)
conn.use('taeyo_db')

or

r.connect(db='taeyo_db').repl()

Manipulating databases

r.db_create('taeyo_db').run(conn)
r.db_drop('taeyo_db').run(conn)
r.db_list().run(conn)

Manipulating tables

r.db("taeyo_db").table_create('authors').run(conn)
r.db("taeyo_db").table_drop('authors').run(conn)
r.db("taeyo_db").table_list().run(conn)

r.table('authors').index_create('post_id').run(conn)
r.table('authors').index_drop('post_id').run(conn)
r.table('authors').index_list().run(conn)
r.table('authors').index_rename('post_id', 'message_id').run(conn)
r.table('authors').index_status().run(conn)

The result will be:

{
    "config_changes": [
        <table configuration data>
    ],
    "tables_created": 1
}

Insert data

r.table("authors").insert([
    { "name": "William Adama", "tv_show": "Battlestar Galactica",
      "posts": [
        {"title": "Decommissioning speech", "content": "The Cylon War is long over..."},
        {"title": "We are at war", "content": "Moments ago, this ship received..."},
        {"title": "The new Earth", "content": "The discoveries of the past few days..."}
      ]
    },
    { "name": "Laura Roslin", "tv_show": "Battlestar Galactica",
      "posts": [
        {"title": "The oath of office", "content": "I, Laura Roslin, ..."},
        {"title": "They look like us", "content": "The Cylons have the ability..."}
      ]
    },
    { "name": "Jean-Luc Picard", "tv_show": "Star Trek TNG",
      "posts": [
        {"title": "Civil rights", "content": "There are some words I've known since..."}
      ]
    }
]).run(conn)

The result will be:

{
    "unchanged": 0,
    "skipped": 0,
    "replaced": 0,
    "inserted": 3,
    "generated_keys": [
        "7644aaf2-9928-4231-aa68-4e65e31bf219",
        "064058b6-cea9-4117-b92d-c911027a725a",
        "543ad9c8-1744-4001-bb5e-450b2565d02c"
    ],
    "errors": 0,
    "deleted": 0
}

Retrieve documents

All documents in a table

cursor = r.table("authors").run()
for document in cursor:
    print(document)

Filter documents based on a condition

cursor = r.table("authors").filter(r.row["name"] == "William Adama").run()
for document in cursor:
    print(document)

Retrieve documents by primary key

This way we can retrieve the document directly without iterating through a cursor.

r.db('test').table('authors').get('7644aaf2-9928-4231-aa68-4e65e31bf219').run()

Realtime feeds

cursor = r.table("authors").changes().run()
for document in cursor:
    print(document)

The code above will print the following messages in the second terminal:

{
  "new_val": {
    "id": "1d854219-85c6-4e6c-8259-dbda0ab386d4",
    "name": "Laura Roslin",
    "posts": [...],
    "tv_show": "Battlestar Galactica",
    "type": "fictional"
  },
  "old_val": {
    "id": "1d854219-85c6-4e6c-8259-dbda0ab386d4",
    "name": "Laura Roslin",
    "posts": [...],
    "tv_show": "Battlestar Galactica"
  }
}

Update documents

Updating All documents in a table

r.table("authors").update({"type": "fictional"}).run()

The result will be:

{
    "unchanged": 0,
    "skipped": 0,
    "replaced": 3,
    "inserted": 0,
    "errors": 0,
    "deleted":0
}

Updating William Adama's record

r.table("authors").
    filter(r.row['name'] == "William Adama").
    update({"rank": "Admiral"}).run()

The result will be:

{
    "unchanged": 0,
    "skipped": 0,
    "replaced": 1,
    "inserted": 0,
    "errors": 0,
    "deleted": 0
}

Delete documents

r.table("authors").
    filter( r.row["posts"].count() < 3 ).
    delete().run()

The result will be:

{
    "unchanged": 0,
    "skipped": 0,
    "replaced": 0,
    "inserted": 0,
    "errors": 0,
    "deleted": 2
}