How to update multiple items in a DynamoDB table at once

Question

I'm using DynamoDB and I need to update a specific attribute on multiple records. Writing my requirement in pseudo-language I would like to do an update that says "update table persons set relationshipStatus = 'married' where personKey IN (key1, key2, key3, ...)" (assuming that personKey is the KEY in my DynamoDB table).

In other words, I want to do an update with an IN-clause, or I suppose one could call it a batch update. I have found this link that asks explicitly if an operation like a batch update exists and the answer there is that it does not. It does not mention IN-clauses, however. The documentation shows that IN-clauses are supported in ConditionalExpressions (100 values can be supplied at a time). However, I am not sure if such an IN-clause is suitable for my situation because I still need to supply a mandatory KEY attribute (which expects a single value it seems - I might be wrong) and I am worried that it will do a full table scan for each update.

So my question is: how do I achieve an update on multiple DynamoDB records at the same time? At the moment it almost looks like I will have to call an update statement for each Key one-by-one and that just feels really wrong...

Answer 1

As you noted, DynamoDB does not support a batch update operation. You would need to query for, and obtain the keys for all the records you want to update. Then loop through that list, updating each item one at a time.