MongoDB – Quick Start Installation and Usage

2 weeks back I attended yet another RHoK Melbourne event and ended up working on a project with NodeJS & MongoDB: both unfamiliar territories for me and thought it would be a good opportunity to create a quick start guide: here is the MongoDB one

Installing and Running the Server

1. Get the binaries on the download page (http://www.mongodb.org/downloads) and get the necessary download for your platform (Windows/Linux/OS X/Solaris). Following commands will be based on OSX but similar actions can be one on other platforms
2. In a terminal, navigate to where you downloaded the package and extract it

   cd ~/Downloads
   tar -zxf mongodb-osx-x86_64-2.4.8.tgz

3. Create a folder to store your database

   cd mongodb-osx-x86_64-2.4.8
   mkdir db

4. Start the server specifying the folder created

   bin/mongod --dbpath=db

Terminology coming from the typical relational database world

Quick start of the MongoDB Shell

1. Connect to the server
   Navigate to the folder where the files are extratcted, run the mongo Javascript shell  (which has tab completion)

   cd ~/Downloads/mongodb-osx-x86_64-2.4.8
   bin/mongo

2. List / show databases

   show dbs

3. Select a database (no need to created a database)

   > use unicorn
   switched to db unicorn
   > db
   unicorn

4. Show collections (tables)

   show collections

5. Inserting a record (row in a table)Collections do not need to be initialised, they are auto generated.
   Below shows the output of the Mongo shell. system.indexes contains indexes for collections

   > show collections
   > db.unicorns.insert({name: 'Aurora', 
      gender: 'f', weight: 450})
   > show collections
   system.indexes
   unicorns

   Mismatched fields

   db.unicorns.insert({name: 'Aurora', gender: 'f', weight: 450})
   db.unicorns.insert({name: 'Leto', gender: 'm', 
       home: 'Arrakeen', worm: false})

   Arrays

   db.unicorns.insert({
       name: 'Solnara', 
       loves:['apple', 'carrot', 'chocolate']})

6. Listing / Querying records

   > db.unicorns.find()
   { "_id" : ObjectId("52b65132eb122da0e6dd19a9"), "name" : "Aurora", "gender" : "f", "weight" : 450 }
   { "_id" : ObjectId("52b6519127026146f128de90"), "name" : "Leto", "gender" : "m", "home" : "Arrakeen", "worm" : false }

   Items have _id auto generated. No need to set an auto increment field.

   Filtering and field selection

   db.collection.find(
      {andedFilters}, 
      {fieldWith1AsShow0asHide}
   )

   Search by name and show only name and worm  fields

   > db.unicorns.find({name: 'Aurora'}, {name: 1, worm:1, _id: 0})
   { "name" : "Aurora" }
   > db.unicorns.find({
       $or: [{name: 'Aurora'}, {'name': 'Leto'}]}, 
      {name: 1, worm:1, _id: 0}
   )
   { "name" : "Leto", "worm" : false }
   { "name" : "Aurora" }

   Paging and Limiting results

   db.unicorns.find().skip(1).limit(2)

   Record Counting

   db.unicorns.count()
   db.unicorns.find({'name' : 'Aurora'}).count()

   Distinct

   db.unicorns.distinct('name')
   db.unicorns.distinct('name', 
      {$or: [{'name' : 'Leto'}, {'name':'Aurora'}]})

7. Query Selectors
   1. Comparison:
      1. $gt / $lt ($gte / $lte): Greater/Less than (or equal).
      2. $ne, $in / $nin: Not equal. In / Non in
   2. Logical: $or, $and, $not, $nor
8. Updating:
   Update first matching record

   db.unicorns.update(
     { name: 'Aurora' }, 
     { $set : { weight: 10 } } 
   )

   Update all matching records

   db.unicorns.update(
     { name: 'Aurora' }, 
     { $set : { weight: 10 } },
     { multi: true }
   )

   Update matching record but insert if doesn’t exist

   db.unicorns.update(
     { name: 'Roooooodles' }, 
     { $set : { weight: 10 } } ,
     { upsert: true }
   )

9. Deleting:
   Deleting all records:

   db.unicorns.remove()

   Delete all matching records

   db.unicorns.remove({name: 'Aurora'})

   Delete only first matching record

   db.unicorns.remove({name: 'Aurora'}, true)

10. Drop collection

    db.unicorns.drop()

Other Considerations

1. No joins. But has embedded documents

   > db.unicorns.insert({name: 'Aurora', gender: 'f', weight: 1450, owner: {'name': ['You', 'Me']}})
   > db.unicorns.find({'owner.name': 'Me'}, {'name': 1, 'owner.name': 1, _id: 0})
   { "name" : "Aurora", "owner" : { "name" : [ "You", "Me" ] } }

Further References

• The Little MongoDB book (got a copy at the MongoDB User Group and it’s a nice short intro. Physically – 34 pages in a A5 format)
• Mongo DB Manual
• GUI-style administrative interface