Is DynamoDB DeleteItem read-consistent?

Question

Dear Experts,

DynamoDB GetItem operations can be read-consistent or not. But there isn't a corresponding setting for DeleteItem. So are DeleteItem operations consistent?

I.e. if one connection does a PutItem, and then another connection does a DeleteItem with the same key, is it guaranteed that the just-put item is actually deleted?

In my case I'm using SetReturnValues(ALL_OLD) to both read and delete an item, if that makes any difference.

Thanks, Phil.

Accepted Answer

Consistency is a term which relates to reads only. All write operations are atomic and will appear in the order they are received, so yes, if you call DeleteItem after a PutItem then it is guaranteed to be deleted.

However, if you call DeleteItem and then PutItem, the item will be there as the PutItem was the last called event. You can add logic to your PutItem with a [ConditionExpression](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.ConditionExpressions.html#Expressions.ConditionExpressions.ConditionalExamples) to only write if it does not already exist.

Answer

Nice question....I can't find any specific documentation but a DeleteItem (as well as PutItem) operation would be considered a write operation and according to [docs](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadConsistency.html) - "When your application writes data to a DynamoDB table and receives an HTTP 200 response (OK), the write has occurred and is durable".

Is DynamoDB DeleteItem read-consistent?

関連するコンテンツ