Write sharding in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a DynamoDB table with a partition key.

DynamoDB

aws dynamodb create-table --table-name UserData --attribute-definitions AttributeName=UserId,AttributeType=[1] AttributeName=ShardId,AttributeType=S --key-schema AttributeName=UserId,KeyType=HASH AttributeName=ShardId,KeyType=RANGE --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5

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

AS

BBOOL

CB

DN

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'N' (number) instead of 'S' for string keys.

The partition key type for user IDs is usually a string, so 'S' is correct.

2fill in blank

medium

Complete the code to add a shard ID attribute to distribute writes.

DynamoDB

aws dynamodb put-item --table-name UserData --item '{"UserId": {"S": "user123"}, "ShardId": {"[1]": "shard1"}}'

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ABOOL

BS

CN

DB

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'N' for shard ID which is a string.

The shard ID is a string, so the attribute type should be 'S'.

3fill in blank

hard

Fix the error in the update expression to increment a shard counter.

DynamoDB

aws dynamodb update-item --table-name UserData --key '{"UserId": {"S": "user123"}, "ShardId": {"S": "shard1"}}' --update-expression "SET WriteCount = WriteCount [1] :inc" --expression-attribute-values '{":inc": {"N": "1"}}'

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A/

B-

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' or '*' which do not increment the value.

To increment the WriteCount, use the '+' operator in the update expression.

4fill in blank

hard

Fill both blanks to create a batch write request for multiple shards.

DynamoDB

aws dynamodb batch-write-item --request-items '{"UserData": [[1], [2]]}'

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A{"PutRequest": {"Item": {"UserId": {"S": "user123"}, "ShardId": {"S": "shard1"}}}}

B{"DeleteRequest": {"Key": {"UserId": {"S": "user123"}, "ShardId": {"S": "shard2"}}}}

C{"PutRequest": {"Item": {"UserId": {"S": "user456"}, "ShardId": {"S": "shard2"}}}}

D{"DeleteRequest": {"Key": {"UserId": {"S": "user456"}, "ShardId": {"S": "shard1"}}}}

Attempts:

3 left

💡 Hint

Common Mistakes

Using DeleteRequest instead of PutRequest for writes.

Batch write needs multiple PutRequest items for different shards to distribute writes.

5fill in blank

hard

Fill all three blanks to create a conditional write that only updates if the shard count is below a limit.

DynamoDB

aws dynamodb update-item --table-name UserData --key '{"UserId": {"S": "user123"}, "ShardId": {"S": "shard1"}}' --update-expression "SET WriteCount = WriteCount + :inc" --condition-expression "WriteCount [1] :max" --expression-attribute-values '{":inc": {"N": "1"}, ":max": {"N": "[2]"}}' --return-values [3]

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A<

B<=

C5

DALL_NEW

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>=' or wrong return values causing errors.

The condition ensures WriteCount is less than 5 before incrementing. 'ALL_NEW' returns the updated item.