Choosing a good shard key in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a sharded collection with a shard key on the 'userId' field.

MongoDB

sh.shardCollection("mydb.users", [1])

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

A{"userId": 1}

B{"userId": "hashed"}

C{"_id": 1}

D{"email": 1}

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string instead of a document for the shard key.

Choosing a field that is not present in the documents.

The shard key must be specified as a document with the field and the index type. Here, 'userId' with ascending order (1) is a common shard key choice.

2fill in blank

medium

Complete the code to shard the 'orders' collection using a hashed shard key on the 'orderId' field.

MongoDB

sh.shardCollection("shop.orders", [1])

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

A{"orderId": 1}

B{"orderId": "hashed"}

C{"customerId": "hashed"}

D{"_id": "hashed"}

Attempts:

3 left

💡 Hint

Common Mistakes

Using ascending (1) instead of 'hashed' for a hashed shard key.

Choosing a different field than intended.

Using a hashed shard key on 'orderId' helps distribute data evenly across shards.

3fill in blank

hard

Fix the error in the shard key specification to shard the 'products' collection on the 'category' field.

MongoDB

sh.shardCollection("store.products", [1])

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

A{"category": 1}

B{"category"}

C{"category": "asc"}

D"category: 1"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string instead of a document for the shard key.

Using an invalid index type like 'asc' or missing the value.

The shard key must be a document with the field name and index type as a number (1 for ascending).

4fill in blank

hard

Fill both blanks to create a shard key on 'region' with ascending order and enable sharding on the database.

MongoDB

[1]
sh.shardCollection("mydb.customers", [2])

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

A{"region": 1}

B{"region": "hashed"}

Csh.enableSharding("mydb")

Dsh.shardCollection("mydb.customers", {"region": 1})

Attempts:

3 left

💡 Hint

Common Mistakes

Not enabling sharding on the database before sharding collections.

Using a hashed shard key when ascending is required.

First, enable sharding on the database, then shard the collection with the shard key document.

5fill in blank

hard

Fill all three blanks to shard the 'logs' collection on 'timestamp' ascending, after enabling sharding on 'analytics' database.

MongoDB

sh.enableSharding([1])
sh.shardCollection([2], [3])

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

A"analytics"

B"analytics.logs"

C{"timestamp": 1}

D"logs"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the collection name without the database prefix.

Not enabling sharding on the database first.

Using incorrect shard key format.

Enable sharding on the 'analytics' database, then shard the 'analytics.logs' collection with 'timestamp' as the shard key ascending.