DynamoDB query() versus getItem() for single-item retrieval based on the index

Question

If I\'m retrieving a single item from my table based on the indexed hash key, is there a performance difference between query() or getItem()?

Answer 1

As suggested by aws employee in one of the discussion, I quote:

The latency of GetItem vs Query with limit=1 will be equivalent.

AWS discussion link

Answer 2

getItem will be faster

getItem retrieve via hash and range key is a 1:1 fit, the time it takes (hence performance) to retrieve it is limited by the hash and sharding internally.

Query results in a search on "all" range keys. It adds computational work, thus considered slower.

Answer 3

In Amazon's DynamoDB, your performances are guaranteed whatever the access method. (you pay for it).

There may be a couple a milliseconds differences on the DynamoDB servers themselves as suggested by Chen Harel but these are negligible because of the HTTP request RTT.

This said, it's a good practice to issue a GET instead of QUERY when you have enough informations to do so.

Answer 4

There is no performance difference between the two. The hash calculation in both the queries are done 1 by 1. The latter, i.e., get item is just provided as an analogy to the JPA repository/spring findOne/findById to make wiring in Spring Bean wiring/ Hibernate configs easier.