- The document is a slide deck for a webinar on building a basic blogging application using MongoDB.
- It covers MongoDB concepts like documents, collections and indexes. It then demonstrates how to install MongoDB, connect to it using the mongo shell, and insert documents.
- The slide deck proceeds to model a basic blogging application using MongoDB, creating collections for users, articles and comments. It shows how to query, update, and import large amounts of seeded data.
9. 9
Installing MongoDB
$ curl -O https://fastdl.mongodb.org/osx/mongodb-osx-ssl-x86_64-3.4.1.tgz
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 60.9M 100 60.9M 0 0 2730k 0 0:00:22 0:00:22 --:--:-- 1589k
$ tar xzvf mongodb-osx-x86_64-3.2.6.tgz
x mongodb-osx-x86_64-3.2.6/README
x mongodb-osx-x86_64-3.2.6/THIRD-PARTY-NOTICES
x mongodb-osx-x86_64-3.2.6/MPL-2
x mongodb-osx-x86_64-3.2.6/GNU-AGPL-3.0
x mongodb-osx-x86_64-3.2.6/bin/mongodump
x mongodb-osx-x86_64-3.2.6/bin/mongorestore
x mongodb-osx-x86_64-3.2.6/bin/mongoexport
x mongodb-osx-x86_64-3.2.6/bin/mongoimport
x mongodb-osx-x86_64-3.2.6/bin/mongostat
x mongodb-osx-x86_64-3.2.6/bin/mongotop
x mongodb-osx-x86_64-3.2.6/bin/bsondump
x mongodb-osx-x86_64-3.2.6/bin/mongofiles
x mongodb-osx-x86_64-3.2.6/bin/mongooplog
x mongodb-osx-x86_64-3.2.6/bin/mongoperf
x mongodb-osx-x86_64-3.2.6/bin/mongosniff
x mongodb-osx-x86_64-3.2.6/bin/mongod
x mongodb-osx-x86_64-3.2.6/bin/mongos
x mongodb-osx-x86_64-3.2.6/bin/mongo
$ ln -s mongodb-osx-x86_64-3.2.6 mongodb
10. 10
Running mongod
JD10Gen:mongodb jdrumgoole$ ./bin/mongod --dbpath /data/b2b
2016-05-23T19:21:07.767+0100 I CONTROL [initandlisten] MongoDB starting : pid=49209 port=27017 dbpath=/data/b2b 64-
bit host=JD10Gen.local
2016-05-23T19:21:07.768+0100 I CONTROL [initandlisten] db version v3.2.6
2016-05-23T19:21:07.768+0100 I CONTROL [initandlisten] git version: 05552b562c7a0b3143a729aaa0838e558dc49b25
2016-05-23T19:21:07.768+0100 I CONTROL [initandlisten] allocator: system
2016-05-23T19:21:07.768+0100 I CONTROL [initandlisten] modules: none
2016-05-23T19:21:07.768+0100 I CONTROL [initandlisten] build environment:
2016-05-23T19:21:07.768+0100 I CONTROL [initandlisten] distarch: x86_64
2016-05-23T19:21:07.768+0100 I CONTROL [initandlisten] target_arch: x86_64
2016-05-23T19:21:07.768+0100 I CONTROL [initandlisten] options: { storage: { dbPath: "/data/b2b" } }
2016-05-23T19:21:07.769+0100 I - [initandlisten] Detected data files in /data/b2b created by the 'wiredTiger'
storage engine, so setting the active storage engine to 'wiredTiger'.
2016-05-23T19:21:07.769+0100 I STORAGE [initandlisten] wiredtiger_open config:
create,cache_size=4G,session_max=20000,eviction=(threads_max=4),config_base=false,statistics=(fast),log=(enabled=true
,archive=true,path=journal,compressor=snappy),file_manager=(close_idle_time=100000),checkpoint=(wait=60,log_size=2GB)
,statistics_log=(wait=0),
2016-05-23T19:21:08.837+0100 I CONTROL [initandlisten]
2016-05-23T19:21:08.838+0100 I CONTROL [initandlisten] ** WARNING: soft rlimits too low. Number of files is 256,
should be at least 1000
2016-05-23T19:21:08.840+0100 I NETWORK [HostnameCanonicalizationWorker] Starting hostname canonicalization worker
2016-05-23T19:21:08.840+0100 I FTDC [initandlisten] Initializing full-time diagnostic data capture with directory
'/data/b2b/diagnostic.data'
2016-05-23T19:21:08.841+0100 I NETWORK [initandlisten] waiting for connections on port 27017
2016-05-23T19:21:09.148+0100 I NETWORK [initandlisten] connection accepted from 127.0.0.1:59213 #1 (1 connection now
open)
11. 11
Connecting Via The Shell
$ ./bin/mongo
MongoDB shell version: 3.2.6
connecting to: test
Server has startup warnings:
2016-05-17T11:46:03.516+0100 I CONTROL [initandlisten]
2016-05-17T11:46:03.516+0100 I CONTROL [initandlisten] ** WARNING: soft rlimits too low. Number of
files is 256, should be at least 1000
>
12. 12
Inserting your first record
> show databases
local 0.000GB
> use test
switched to db test
> show databases
local 0.000GB
> db.demo.insert( { "key" : "value" } )
WriteResult({ "nInserted" : 1 })
> show databases
local 0.000GB
test 0.000GB
> show collections
demo
> db.demo.findOne()
{ "_id" : ObjectId("573af7085ee4be80385332a6"), "key" : "value" }
>
17. 17
In MongoDB we can build organically
> use blog
switched to db blog
> db.users.insert( { "username" : "jdrumgoole", "password" : "top secret", "lang" : "EN" } )
WriteResult({ "nInserted" : 1 })
> db.users.findOne()
{
"_id" : ObjectId("573afff65ee4be80385332a7"),
"username" : "jdrumgoole",
"password" : "top secret",
"lang" : "EN"
}
18. 18
How do we do this in a program?
'''
Created on 17 May 2016
@author: jdrumgoole
'''
import pymongo
#
# client defaults to localhost and port 27017. eg MongoClient('localhost', 27017)
client = pymongo.MongoClient()
blogDatabase = client[ "blog" ]
usersCollection = blogDatabase[ "users" ]
usersCollection.insert_one( { "username" : "jdrumgoole",
"password" : "top secret",
"lang" : "EN" })
user = usersCollection.find_one()
print( user )
19. 19
Next up Articles
…
articlesCollection = blogDatabase[ "articles" ]
author = "jdrumgoole"
article = { "title" : "This is my first post",
"body" : "The is the longer body text for my blog post. We can add lots of text here.",
"author" : author,
"tags" : [ "joe", "general", "Ireland", "admin" ]
}
#
# Lets check if our author exists
#
if usersCollection.find_one( { "username" : author }) :
articlesCollection.insert_one( article )
else:
raise ValueError( "Author %s does not exist" % author )
20. 20
Create a new type of article
#
# Lets add a new type of article with a posting date and a section
#
author = "jdrumgoole"
title = "This is a post on MongoDB"
newPost = { "title" : title,
"body" : "MongoDB is the worlds most popular NoSQL database. It is a document
database",
"author" : author,
"tags" : [ "joe", "mongodb", "Ireland" ],
"section" : "technology",
"postDate" : datetime.datetime.now(),
}
#
# Lets check if our author exists
#
if usersCollection.find_one( { "username" : author }) :
articlesCollection.insert_one( newPost )
33. 33
We need an index
> db.users.createIndex( { username : 1 } )
{
"createdCollectionAutomatically" : false,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}
>
34. 34
Indexes Overview
• Parameters
– Background : Create an index in the background as opposed to locking the database
– Unique : All keys in the collection must be unique. Duplicate key insertions will be
rejected with an error.
– Name : Explicitly name an index. Otherwise the index name is autogenerated from the
index field.
• Deleting an index
– db.users.dropIndex({ “username” : 1 })
• List indexes
– db.users.getIndexes()
35. 35
Query Plan Execution Stages
• COLLSCAN : for a collection scan
• IXSCAN : for scanning index keys
• FETCH : for retrieving documents
• SHARD_MERGE : for merging results from shards
38. 38
What we have learned
• How to create a database and a collection
• How to insert content into that collection
• How to query the collection
• How to update a document in place
• How to delete a document
• How to check the efficiency of an operation
• How to add an index
• How to check an index is being used in an operation
39. 39
Next Webinar : Introduction to Replica Sets
• How to ensure your data is durable
• How to recover from failures automatically
• How to write safe client code
Thursday, 2-Feb-2016, 11:00 am GMT.