How to get total number of pages in DynamoDB if we set a limit?

Question

I have a list of documents that are stored in DynamoDB. There are more than 10,000 documents being stored in the db. I have set the limit to 100 when requesting. DynamoDB is doing a good job by returning me the first 100 documents and the LastEvaluatedKey to get the next 100 documents.

The problem here is I also want the DynamoDB to return me the total number of pages for pagination purpose. In this case since i have 10,000 documents it should return 100 (the number of pagination)

For now what I have done is that I have been counting manually by looping the queries until it doesn't return me the LastEvaluatedKey. Add up how many looping has been done to get the total page. But I believe there are better approach.

Answer 1

As the other answer has correctly explained, there is no efficient way to get total result counts for DynamoDB query or scan operations. As such there is no efficient way to get total number of pages.

However, what I wanted to call out is that modern UIs have been moving away from classic pagination towards an infinite scroll design pattern. Where the “next page” of results is loaded on demand as the List is scrolled. This can be achieved with DynamoDB. You can still show discrete pages but cannot show, apriori, how many results or how many pages there are.. It’s a current shortcoming of DynamoDB.