How do you query DynamoDB?

Solution 1:

Yes, you are correct about the trade-off between performance and query flexibility.

But there are a few tricks to reduce the pain - secondary indexes/denormalising probably being the most important.

You would have another table keyed on user ID, listing all their images, for example. When you add an image, you update this table as well as adding a row to the table keyed on image ID.

You have to decide what queries you need, then design the data model around them.

Solution 2:

I think you need create your own secondary index, using another table.

This table "schema" could be:

    User ID (String, Primary Key)
    Date Added (Number, Range Key)
    Image ID (Number)

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That way you can query by User ID and filter by Date as well

Solution 3:

You can use composite hash-range key as primary index.

From the DynamoDB Page:

A primary key can either be a single-attribute hash key or a composite hash-range key. A single attribute hash primary key could be, for example, “UserID”. This would allow you to quickly read and write data for an item associated with a given user ID.

A composite hash-range key is indexed as a hash key element and a range key element. This multi-part key maintains a hierarchy between the first and second element values. For example, a composite hash-range key could be a combination of “UserID” (hash) and “Timestamp” (range). Holding the hash key element constant, you can search across the range key element to retrieve items. This would allow you to use the Query API to, for example, retrieve all items for a single UserID across a range of timestamps.