Amazon DynamoDDB: Are there limits on programmatic changes to a table provisioned throughput?

Question

I am processing a large set of files as follows: I first download all of them to an EC2 instance and then I run a script that sequentially processes each file and indexes it into a DynamoDDB table (each item in the table corresponds to a single line in a file). Then I download the next batch of files etc.

Right now I adjust provisioned throughput via AWS GUI console and it ends up being the same during both the download phase and the indexing phase. Clearly, this is suboptimal since while downloading I do not talk to the database at all so my required write throughput during this phase is essentially 0.

So what I want to do is programmatically adjust provisioned throughput way up when I start indexing and then way down when I stop indexing and start downloading.

Are there any limits on how much I can increase write t/p in a single request? For instance, can I change it from 5 to 120? If not, how do i calculate the number of requests and the time required to adjust t/p from value X to value Y (where X << Y)? Do I have to do similar calculation for decreasing t/p?

I am using Python boto.

Thanks

Answer 1

When scaling up you can only double your write provision, so if you are at 5, you can up to 10, then wait the 20-30 seconds for it to kick in, then double again to 20 and so on. You can scale down as low as you like.

As per the AWS FAQ:

Q: Is there any limit on how much I can change my provisioned throughput with a single request? Yes. Amazon DynamoDB allows you to change your provisioned throughput level by up to 100% with a single UpdateTable API call. If you wish to increase your throughput by more than 100%, you can simply call UpdateTable again.

For example, if your table has 1,000 units of write capacity provisioned, you could not update your table to 3,000 with a single API call as that is more than the maximum allowed change for a single UpdateTable operation. To increase your throughput from 1,000 to 3,000 units of write capacity, simply call UpdateTable to first double your throughput to 2,000, then call UpdateTable a second time to reach 3,000 writes/second.