Batch processing and Unprocessed records clarification

[jamesgibbons92]

From the docs:

Elements of the unprocessed array are unlike results received from a query. Instead of containing all the attributes of a record, an unprocessed record only includes the composite attributes defined in the Table Index. This is in keeping with DynamoDB’s practice of returning only Keys in the case of unprocessed records. For convenience, ElectroDB will return these keys as composite attributes, but you can pass the [execution option](https://electrodb.dev/en/queries/batch-get/#execution-options) {unprocessed:"raw"} override this behavior and return the Keys as they came from DynamoDB.

When using the default options, I am not seeing this behavior when inspecting unprocessed results, the records contain all the attributes of the item passed into the batch put call, not just the composite attributes.

Ideally I want to just pass the unprocessed items back into entity.put() to re-process with some back-off retry logic, which is a pattern we use with the native dynamodb client as recommended by their documentation "the UnprocessedItems value is in the same form as RequestItems, so you can provide this value directly to a subsequent BatchWriteItem operation" https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_BatchWriteItem.html#API_BatchWriteItem_ResponseSyntax

This is not so straightforward with ElectroDB as the response type is AllTableIndexCompositeAttributes<>[], currently I have to do some filtering on the original items to filter out the unprocessed items based on the comp attributes.

I've also seen the 'raw' processing option but the type is still AllTableIndexCompositeAttributes<>[].

So to summarize my points:

1. Shouldn't the default behavior and type of unprocessed records be of PutItem type? Which would be in keeping with the response type of the DynamoDB client. This would allow user to pass the items back into another put() to retry.
2. If the type must be AllTableIndexCompositeAttributes then it seems there is a bug as the records contain more than the composite attributes.
3. Can the unprocessed response type correctly reflect the response options, when using 'items' or 'raw'.

Many thanks

[squio]

@tywalch looking at the source code (v2.12.3 and current Master branch) it seems that the observations in this issue are still correct.

If so, can this be reflected in documentation to make it possible to rely on this behavior?