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As part of our MongoDB Guide, we’ve compiled this cheat sheet of common and not-so-common MongoDB commands.

Table of Contents

Pretty Print
Create Collection
Create Indexes
Create index
Create sparse index
Create compound index
Create geo index
Create partial index
Add and Delete Data
Add one data record
Add array (many) records
Delete data
Query MongoDB Documents
Search by attribute
Search by geolocation
Search greater or less than
Search not equal to
Search and return only certain fields
Search by regular expression
Find by elements in array
Replication and Sharding
Enable replication
Add shard
Show Server Memory
Aggregate functions
MapReduce

Pretty Print

Add pretty() to the end of any search:

db.collection.find({}).pretty()

Create Collection

db.createCollection("<collection name>")

Create Indexes

Create index

The format is {attribute : sortOrder} where sort order is -1 (descending) or 1 (ascending).

db.cars.createIndex( { make: 1 } )

Create sparse index

This does not index documents that do not have this attribute.

db.products.createIndex({product:-1},{sparse: true})

Create compound index

db.cars.createIndex( { make: 1 , model: -1} )

Create geo index

db.address.createIndex( { "location": "2dsphere"} )

Create partial index

This indexes those documents that match the search criteria.

db.students.createIndex(
{ age: 1},
{ partialFilterExpression: { age: { $gt: 14}}}
)

Add and Delete Data

Add one data record

db.cars.insert([
{
vin: 1111111111,
model: 'SK-202',
make: 'Mercedes'
}
])

Add array (many) records

db.cars.insertMany([
{
vin: 1111111111,
model: 'SK-202',
make: 'Mercedes'
},
{
vin: 2222222,
model: 'Cabriolet',
make: 'Chevrolet' }
])

Delete data

db.cars.remove({"make": "Chevrolet"})

Query MongoDB Documents

Search by attribute

db.cars.find({ "make": "Mercedes"}

Search by geolocation

db.address.find ({
location: {
$near: {
$geometry: {
type: "Point" ,
coordinates: [ -72.7738706,41.6332836 ]
},
$maxDistance: 4,
$minDistance: 0
}
}
})

Search greater or less than

db.sales.find({"price": {$gt: 100}})

Search not equal to

db.cars.find({make: {$not: {$eq: "Mercedes"}}})

Search and return only certain fields

This is called projection.

Show only the make field:

db.cars.find({make: "Mercedes"}, {vin: -1})

Show every field except the make field:

db.cars.find({make: "Mercedes"}, {vin: 0})

Search by regular expression

You can use the slash or quote marks as a delimiter.

db.cars.find({"make": {$regex: /^M.*/}})

Case insensitive:

db.cars.find({"make": {$regex: /^merc.*/, $options: "i"}} )

Find by elements in array

This matches documents that contain all of these array elements:

db.manufacturers.find({"name": {$all: [ "Mercedes", "Ford" ]}} )

Match on any element in the array:

db.manufacturers.find({"name": "Ford"} )

Replication and Sharding

Enable replication

Connect to a config server then:

rs.initiate()

And then show replication status:

rs.status()

Add shard

Connect to query router (mongos) server. 27018 in this example is the port number of a shard server

sh.addShard( "ShardReplSet/172.31.47.43:27018")

Show Server Memory

db.serverStatus().mem

Aggregate functions

This is the same as the SQL select count(*) from words group by word. This is the word count program.

db.words.aggregate([ {$group: { _id: "$word", cnt: {$sum: 1} } } ])

MapReduce

You can do the same word count function using the map operation:

db.words.mapReduce(
function() { emit(this.word,1); },
function(key, values) {return Array.sum(values)}, {
query:{},
} out:"total_matches"
).find()

Free E-book: The Beginner’s Guide to MongoDB

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Last updated: 05/27/2020

These postings are my own and do not necessarily represent BMC's position, strategies, or opinion.

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About the author

Walker Rowe

Walker Rowe

Walker Rowe is an American freelancer tech writer and programmer living in Cyprus. He writes tutorials on analytics and big data and specializes in documenting SDKs and APIs. He is the founder of the Hypatia Academy Cyprus, an online school to teach secondary school children programming. You can find Walker here and here.