Prepare for Amazon’s AWS Data Analytics – Specialty certification and test your knowledge on DynamoDB.
Questions on the following topic(s) are included –
AWS Data Analytics – Quiz 2: DynamoDB
1 / 10
In DynamoDB tables, which of the following cannot be defined or updated after table creation?
a) Incorrect. Both Read and Write Capacity Units (RCU, WCU) can be updated after table creation.b) Correct. Local Secondary Index can only be defined at table creation.c) Incorrect. Global Secondary Index can be defined at any time.d) Correct. The Sort key must be defined at table creation and cannot be added later.
2 / 10
Which of the following are ways to trigger real-time actions from DynamoDB?
a) Incorrect – does not existb) Correct – the DynamoDB stream can be read by Lambdac) Correct – Kinesis Client Library can consume directly form DynamoDB Streamsd) Incorrect – Kinesis Firehose cannot consume directly from DynamoDB Streams
3 / 10
A DynamoDB table needs to hold 100GB data and support 9000 RCU, 9000 WCU
How many partitions will it have?
To calculate the number of partitions, find the biggest of Data Size/10GB and (RCU/3K + WCU/1K)
In this case RCU/3K + WCU/1K = 12 whilst Data Size/10GB = 10, so there will be 12 partitions
4 / 10
Which of the following is not a DynamoDB API call?
d) Correct. DynamoDB is not a relational database, so does not have foreign keys built-in.
All other options are valid API calls:
5 / 10
Which of the following is true for DynamoDB?
a) Correct, the Max row (item) size is 400KB
6 / 10
Which of the following are is a valid way of using DynamoDB with large objects?
a) Correct – store the file in S3, but reference it’s key in DynamoDBb) Incorrect – there is no such ‘multipartID’ capabilityc) Incorrect – you may need DynamoDB’s performance, scale and low cost whilst using S3 for lower cost large object storage.d) Incorrect – you can tag the object is S3, but DynamoDB wouldn’t be aware.
7 / 10
An small online retailer is using DynamoDB to support its e-commerce shopping carts.
Based on peak shopping traffic, they are expecting 10,000 objects per second of 5KB write and 40,000 objects per second of 3KB read. Strongly consistent reads are required.
What should the corresponding e-commerce cart table be configured with?
1 WCU = one write/sec per 1KB item. So WCU = 10,000 * 5 = 50,000
1 RCU = one read/sec per 4KB item, rounding up to nearest 4KB. So RCU = 40,000 * 4 = 160,000
a) Incorrect. TTL does not use up WCU/RCU so would not cause the exceptionb) Correct. This table has been poorly partitioned and there is a good chance of a ‘hot partition’ due to high demand for a particular game in a specific country. User_ID would have provided much higher cardinality and a better key, with less chance of exceptions.c) Incorrect. In fact DynamoDB Acceleration (caching) may help mitigate the risk of exceptions, and will definitely not contribute to this particular exception.d) Correct. Scans can consume a lot of RCU
8 / 10
An MMO game leaderboard is being stored in DynamoDB. Which of the following could cause ‘ProvisionedThroughputException’ from DynamoDB?
9 / 10
Which of the following are true for Local & Global Indexes in DynamoDB?
a) Correct – LSI can only be set at table creation timeb) Incorrect – GSI can be set at any timec) Incorrect – GSI creates a new table, LSI is an attribute of the original tabled) Correct – RCU/WCU must be set for table created by GSI
10 / 10
What is the most efficient way to delete expired data from DynamoDB Tables?
a) Incorrect. This could work, but is not the most efficient. Code must be written and there could be a performance impact on the tableb) Incorrect. This is the right idea, but TTL requires you to create an epoch to capture the expiry datac) Correct. You need to create the expiry attribute and point TTL to it. Each row (item) in the table would need an expiry attribute. There is no RCU/WCU impact of associated deletesd) Incorrect. This doesn’t exist (you may be thinking of S3 auto-tiering?)
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