dynamodb attribute name compression

Question

I have a dynamodb table where attribute names are large string, but whole item is of 1KB only. Shall I reduce attribute names to small string for network and storage performance since each item will have attribute names as well as value or dynamodb will automatically compress that to short codes and then store ?

Answer 1

While it is true that single item reads are charged indirectly via provisioned capacity units in increments of 4KB while writes are charged in increments of 1KB, these calculations during a query or table scan are used against the summed total read or written data size.

In other words, using short attribute names does help significantly in increasing throughput capacity (for the same provisioned price) for queries since you can read many more items per second since each item is smaller in size so it takes more of them to get to 4 KB for reads or 1 KB for writes where a capacity unit is consumed.

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/CapacityUnitCalculations.html

"Note We recommend that you choose shorter attribute names rather than long ones. This will help you optimize capacity unit consumption and reduce the amount of storage required for your data."

Note also that numbers are stored more compactly with 2 digits per byte compared to strings. So an ISO format datetime (e.g. 2018-02-21T10:17:44.123Z) that contains letters will take up much more space (24 bytes) than storing it as a number (e.g. 20180221101744.123) leaving out the letters taking up less space (10 bytes -- each digit pair is one byte plus one byte for sign and decimal places)

Answer 2

Attribute names are user-determined except for the primary keys of the base table and indexes, so DynamoDB is not able to optimize on storing attribute names. Furthermore writes are charged in 1KB increments. It does not matter if your item size is 600 or 1000 bytes; such an item will incur 1 WCU to write. For usability purposes, it is better to have human-readable attribute names so if your application permits it, perhaps leave the attribute names as is?