DynamoDB query() versus getItem() for single-item retrieval based on the index
Amazon Web-ServicesAmazon DynamodbAmazon Web-Services Problem Overview
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()
?
Amazon Web-Services Solutions
Solution 1 - Amazon Web-Services
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.
Solution 2 - Amazon Web-Services
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.
Solution 3 - Amazon Web-Services
As suggested by aws employee in one of the discussion, I quote:
> The latency of GetItem vs Query with limit=1 will be equivalent.
Solution 4 - Amazon Web-Services
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.