diff --git a/DynamoDB/Practice/Read and Write Units - Set 3.md b/DynamoDB/Practice/Read and Write Units - Set 3.md new file mode 100644 index 0000000..44a7739 --- /dev/null +++ b/DynamoDB/Practice/Read and Write Units - Set 3.md @@ -0,0 +1,96 @@ +# DynamoDB Read/Write Units — Numeric Practice, Set 3 + +20 questions. Give a numeric answer for each, using `1 = `, `2 = `, and so on. + +## Assumptions + +- Assume provisioned capacity and steady workloads. +- All item sizes are exact DynamoDB item sizes, including attribute names and values. +- Each read accesses an individual item, not a Query or Scan. Transactional operations count individual items, not transaction API calls. +- Normal writes are non-transactional. All writes create new items. +- Ignore indexes, replication, retries, failed requests, burst capacity and partition limits. +- Questions 1–14 ask for exact throughput requirements: fractional RCU answers are valid; do not round the final result to a whole number. +- Questions 15–18 ask for the maximum number of individual item operations per second. +- Questions 19–20 ask for whole-number provisioned capacity settings. + +## Questions + +### 1. You normally write six separate 1.8 KB items every second. How many WCUs are required? + +Answer: ______ + +### 2. You normally write nine separate 0.7 KB items every second. How many WCUs are required? + +Answer: ______ + +### 3. You normally write four separate 3.01 KB items every second. How many WCUs are required? + +Answer: ______ + +### 4. You transactionally write three separate 2.01 KB items every second. How many WCUs are required? + +Answer: ______ + +### 5. You transactionally write six separate 1 KB items every second. How many WCUs are required? + +Answer: ______ + +### 6. You perform strongly consistent reads of five separate 5 KB items every second. How many RCUs of throughput are required? + +Answer: ______ + +### 7. You perform strongly consistent reads of three separate 12 KB items every second. How many RCUs of throughput are required? + +Answer: ______ + +### 8. You perform eventually consistent reads of nine separate 0.8 KB items every second. How many RCUs of throughput are required? + +Answer: ______ + +### 9. You perform eventually consistent reads of five separate 8.01 KB items every second. How many RCUs of throughput are required? + +Answer: ______ + +### 10. You perform eventually consistent reads of seven separate 8 KB items every second. How many RCUs of throughput are required? + +Answer: ______ + +### 11. You transactionally read five separate 4.01 KB items every second. How many RCUs of throughput are required? + +Answer: ______ + +### 12. You transactionally read three separate 11 KB items every second. How many RCUs of throughput are required? + +Answer: ______ + +### 13. Each second, you normally write two 0.6 KB items and three 2.4 KB items to the same table. How many WCUs are required in total? + +Answer: ______ + +### 14. Each second, you perform strongly consistent reads of two 5 KB items and eventually consistent reads of three 1 KB items from the same table. How many RCUs of throughput are required in total? + +Answer: ______ + +### 15. You have 28 WCUs available. What is the maximum number of normal item writes per second you can sustain if each item is 3.2 KB? + +Answer: ______ + +### 16. You have 30 WCUs available. What is the maximum number of transactional item writes per second you can sustain if each item is 2.2 KB? + +Answer: ______ + +### 17. You have 15 RCUs available. What is the maximum number of eventually consistent item reads per second you can sustain if each item is 9 KB? + +Answer: ______ + +### 18. You have 32 RCUs available. What is the maximum number of transactional item reads per second you can sustain if each item is 5 KB? + +Answer: ______ + +### 19. You perform eventually consistent reads of eleven separate 3 KB items every second. What is the minimum WHOLE NUMBER of RCUs you must provision? + +Answer: ______ + +### 20. You perform eventually consistent reads of five separate 12.01 KB items every second. What is the minimum WHOLE NUMBER of RCUs you must provision? + +Answer: ______