AWS DynamoDb : Pricing for On-demand Indexes

Question

I need to create a secondary index on my DynamoDb table. For this table, I have set the read/write capacity mode to On-demand.

To query the data based on a particular column in the table, I want to create an index. ( this column is sort key, so I won't be able to perform queries only on this column)

When I created the index through the DynamoDB console, by default the read capacity for this index is "on-demand".

I want to confirm how the pricing works for this index.

I was referring to this page - https://aws.amazon.com/dynamodb/pricing/

Will it be based on number of read and write operations on this index? I am assuming there will be no fixed cost (like provisioned capacity).

Answer 1

I did a small experiment.

I created one table with on-demand capacity mode and another with provisioned capacity mode.

I created indexes on each of these table.

On the table with provisioned capacity mode, I could create an index with provisioned capacity mode only.

On the on-demand capacity mode, I was able to create an index with only on-demand capacity mode.

So I think my understanding is correct.

When we create an index with on-demand capacity mode, the pricing depends upon the number of writes and reads to the table and the index.

Answer 2

DynamoDB charges for reading, writing, and storing data in your DynamoDB tables, along with any optional features you choose to enable.

DynamoDB has two capacity modes and those come with specific billing options for processing reads and writes on your tables:

1. on-demand
2. provisioned

Please read the attached link for more details.