GetItem on index in dynamodb-enhanced dependency

[ashr123]

Describe the feature

We need to be able to make a GetItem operation on a "slim" index instead of the main table

Use Case

average size of items in the main table is ~2KB and the average size of items in our GSI is ~100 bytes, that means much less read units consumed.

We can do it by QueryItem and use Stream::findAny but it's less elegant (and maybe slower?)
it will eliminate the current flow:

 sdkIterable.stream()
		.map(Page::items)
		.flatMap(Collection::stream)
		.findAny()

With just getting the generic T item (or Optional<T>)

Proposed Solution

add the ability to get a single item from an DynamoDbIndex and update GetItem as it should not be a breaking change, just an optional field addition.

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

AWS Java SDK version used

2.20.157

JDK version used

17

Operating System and version

MacOS 14.4, Ubuntu 22.04

[debora-ito]

The low-level DynamoDB GetItem only works with primary keys though, it doesn't take an index. So I don't think there's a way to support this in the enhanced client.

You can use QueryEnhancedRequest#AttributesToProject to reduce the number of attributes retrieved.

[ashr123]

@debora-ito first of all, can't you make the necessary changes to the low-level GetItem? why does it exists only for the main table?
Second, QueryEnhancedRequest#AttributesToProject doesn't help as it will consume the same read units for the whole item and not for the projected attributes, right?