How to do it...

1. Start with the size of the items, in kilobytes (KB):

ItemSize = Size of the items (rows) in KB

2. Work out the required number of RCUs required by dividing the number by 4, and rounding up:

RCU Per Item = ItemSize / 4 (rounded up)

3. Define the expected number of read operations per second. This is one of the numbers you will use to provision your table with:

Required RCU = Expected Number of Reads * RCU Per Item

4. Divide the number by 3,000 to calculate the number of DDB partitions required to reach the capacity:

Read Partitions = Required RCU / 3,000

5. Next, work out the write capacity required by dividing the item size by 1, and rounding up:

WCU Per Item = ItemSize / 1 (rounded up)

6. Define the expected number of write operations per second. This is one of the numbers you will use to provision your table with:

Required WCU = Expected Number of Writes * WCU Per Item

7. Divide the number by 1,000 to calculate the number of DDB partitions required to reach the capacity:

Write Partitions = Required WCU / 1,000

8. Add these two values to get the capacity partitions required (rounding up to a whole number):

Capacity Partitions = Read Partitions + Write Partitions (rounded up)

9. Work out the minimum number of partitions required by the amount of data you plan to store:

Size Partitions = Total Size in GB / 10 (rounded up)

10. Once you have the partition requirements for your use case, take the maximum of your previous calculations:

Required Partitions = Maximum value between Capacity Partitions and Size Partitions

11. Since your allocated capacity is spread evenly across partitions, divide the RCU and WCU values to get the per-partition performance of your table:

Partition Read Throughput = Required RCU / Required Partitions

Partition Write Throughput = Required WCU / Required Partitions