Chunks and balancer concept in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to list all chunks in a sharded collection.

MongoDB

db.getSiblingDB('config').chunks.find({ 'ns': [1] })

Drag options to blanks, or click blank then click option'

A'chunks'

B'mydb'

C'mydb.mycollection'

D'config.chunks'

Attempts:

3 left

💡 Hint

Common Mistakes

Using only the database name instead of the full namespace.

Using the collection name alone without the database prefix.

The ns field specifies the namespace (database.collection) for the chunks. You must provide the full namespace string.

2fill in blank

medium

Complete the command to enable the balancer in MongoDB.

MongoDB

sh.setBalancerState([1])

Drag options to blanks, or click blank then click option'

A0

Btrue

C1

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Passing 1 or 0 instead of true or false.

Using quotes around true or false.

To enable the balancer, you must pass true to sh.setBalancerState().

3fill in blank

hard

Fix the error in the command to get the current balancer status.

MongoDB

sh.[1]()

Drag options to blanks, or click blank then click option'

AgetBalancerState

BbalancerStatus

CgetBalancerStatus

DbalancerState

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'balancerStatus' or 'getBalancerStatus' which are not valid methods.

Using 'balancerState' without 'get'.

The correct method to get the balancer state is sh.getBalancerState().

4fill in blank

hard

Fill both blanks to create a query that finds chunks with a max key greater than 100.

MongoDB

db.getSiblingDB('config').chunks.find({ 'max.[1]': { [2]: 100 } })

Drag options to blanks, or click blank then click option'

AshardKey

B$gt

C$lt

DminKey

Attempts:

3 left

💡 Hint

Common Mistakes

Using '$lt' instead of '$gt' for greater than.

Using 'minKey' instead of the shard key field.

The shard key field is used to check the max value. The operator $gt means 'greater than'.

5fill in blank

hard

Fill all four blanks to create a command that moves a chunk to a specific shard.

MongoDB

sh.moveChunk('[1]', { '[2]': [3] }, '[4]')

Drag options to blanks, or click blank then click option'

Amydb.mycollection

BshardKey

C100

Dshard0001

Attempts:

3 left

💡 Hint

Common Mistakes

Using only the collection name for namespace.

Using the wrong shard key field name.

Using a string instead of a number for the shard key value.

The first argument is the namespace, the second is the shard key value to identify the chunk, and the third is the destination shard name.