Mongo Commands

Question 1

How can I create a new db?

Answer 1

implicit with use statement (directory created as soon as data is inserted, there are no empty databases, empty is automatically removed)

-> use newdb

Question 2

How can I insert?

Answer 2

dbname.collection.insert({ “field”: 123 })

Question 3

How can I delete?

Answer 3

Explicit (drops database with data)
dbname.runCommand({ dropDatabase: 1 })
or with wrapper command
db.dropDatabase()

Question 4

What are capped Collections?

Answer 4

collections with a max size defined during creation
- follows the FIFO principle

db.createCollection(“capping”, {capped: true, size:4096, max: 10})

Question 5

What are Time Series Collections?

Answer 5

stores sequences of measurements effectively

Question 6

What are Embedded Documents?

Answer 6

a field can contain arrays or documents

Question 7

How is a MongoDB find query structured?

Answer 7

db.<collection>.find(<criteria>, <projection>)</projection></criteria></collection>

Question 8

What is a MongoDB Cursor?

Answer 8

When running find, the result is returned as a cursor / a iterator over a result set.

var cursor = db.<collection>.find({ "user_verified": true }, { text: 1, "user_verified": 1, "user.screen_name": 1, "user.friends_count": 1})</collection>

further cursor commands in pdf 4