Which indexes in DynamoDB allow for a choice of sort keys?

Local secondary indexes (LSIs) in DynamoDB allow for a choice of sort keys while sharing the same partition key as the base table. This means that for each item in the main table, you can create multiple local secondary indexes, each with a different sort key. This capability is particularly useful when you want to query data based on different attributes or ranges of values while keeping the same partitioning scheme.

By allowing multiple sort keys, LSIs enable more flexible querying options on the same set of items, enhancing the ability to retrieve data efficiently based on additional criteria beyond the primary key.

It's important to note that while global secondary indexes (GSIs) can provide additional flexibility—allowing for different partition keys and sort keys across potentially different data distributions—they do not utilize the same partition key, thus making LSIs unique in their ability to share this aspect. This distinction underlines the local secondary index's capability to serve specific use cases where sorting based on multiple attributes under a uniform partitioning strategy is desired.