DynamoDB Table Capacity
Question
You've define a DynamoDB table with a read capacity of 5 and a write capacity of 5
Which of the following statements are TRUE? Choose 3 answers from the options given below.
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D. E.Answer - A, D and E.
This is also given in the AWS Documentation.
For example, suppose that you create a table with 5 read capacity units and 5 write capacity units.
With these settings, your application could:
Perform strongly consistent reads of up to 20 KB per second (4 KB × 5 read capacity units).
Perform eventually consistent reads of up to 40 KB per second (twice as much read throughput).
Write up to 5 KB per second (1 KB × 5 write capacity units).
Based on the documentation, all other options are incorrect.
For more information on provisioned throughput, please refer to the below URL-
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ProvisionedThroughput.htmlThe answer options provided are:
A. Strong consistent reads of a maximum of 20 KB per second B. Eventual consistent reads of a maximum of 20 KB per second C. Strong consistent reads of a maximum of 40 KB per second D. Eventual consistent reads of a maximum of 40 KB per second E. Maximum writes of 5KB per second.
First, let's understand the concept of read and write capacity in DynamoDB:
DynamoDB is a NoSQL database that provides fast and predictable performance with seamless scalability. To achieve this, DynamoDB uses the concept of provisioned throughput, which allows you to specify the read and write capacity for your table, in terms of read capacity units (RCUs) and write capacity units (WCUs), respectively.
One RCU represents one strongly consistent read of up to 4 KB per second, or two eventually consistent reads of up to 4 KB per second. Similarly, one WCU represents one write of up to 1 KB per second.
Now, let's analyze the answer options:
A. Strong consistent reads of a maximum of 20 KB per second: Since the table has a read capacity of 5, and each RCU can provide up to 4 KB per second, the maximum strong consistent reads per second would be 5 x 4 KB = 20 KB per second. This option is correct.
B. Eventual consistent reads of a maximum of 20 KB per second: As explained earlier, one RCU can provide two eventually consistent reads of up to 4 KB per second. Therefore, the maximum eventual consistent reads per second would be 2 x 5 x 4 KB = 40 KB per second. This option is incorrect.
C. Strong consistent reads of a maximum of 40 KB per second: This option is incorrect since the read capacity of the table is only 5, and each RCU can provide up to 4 KB per second. Therefore, the maximum strong consistent reads per second would be 5 x 4 KB = 20 KB per second.
D. Eventual consistent reads of a maximum of 40 KB per second: This option is incorrect since the maximum eventual consistent reads per second would be 2 x 5 x 4 KB = 40 KB per second, as explained in option B. However, the option mentions eventual consistent reads, which cannot be guaranteed to return the latest data.
E. Maximum writes of 5KB per second: Since the table has a write capacity of 5, and each WCU can provide up to 1 KB per second, the maximum writes per second would be 5 x 1 KB = 5 KB per second. This option is correct.
Therefore, the correct options are A, E, and any one of B or D.
