CODEWITHSUNDEEP
amazon-web-servicesamazon-dynamodb
ensnare
ensnare

Reputation: 42013

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

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()?

Upvotes: 89

Views: 58789

Answers (4)

Chen Harel
Chen Harel

Reputation: 10052

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.

Edit: Just for quick comparison adding the following picture from this blog entry.

Decision diagram which retrieval function to use

Upvotes: 72

Deep Patel
Deep Patel

Reputation: 739

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

Upvotes: 31

purpleguy
purpleguy

Reputation: 64

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.

Upvotes: 1

yadutaf
yadutaf

Reputation: 7132

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.

Upvotes: 31

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