using "contains" for query key condition in dynamoDB

Question

I am trying to query my dynamodb with contains comparison parameter, but it is not working

data= table.query(
    IndexName='farm_name-index',
    KeyConditionExpression = Key('user_name').eq(user_name)& contains(Key('farm_zone_id_time_stamp'),farm_zone_id_time_stamp)& Key('time_stamp').between(from_time,to_time) 
    )

and i am getting the following error :

name 'contains' is not defined: NameError
Traceback (most recent call last):
  File "/var/task/lambda_function.py", line 25, in lambda_handler
    KeyConditionExpression = Key('user_name').eq(user_name)& contains(Key('farm_zone_id_time_stamp'),farm_zone_id_time_stamp)& Key('time_stamp').between(from_time,to_time)
NameError: name 'contains' is not defined

can any one tell me the right way to doit ?

hunterhacker · Accepted Answer · 2022-01-31 20:17:04Z

2

You cannot do contains on a sort key. You can do equality, begins_with, or comparison operators only.

Here's the list from the docs: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Query.html#Query.KeyConditionExpressions

Why? Because these are the operators that are efficient for pulling data out of a sorted list, such as is put under the sort key.

With DynamoDB you can use a filter expression for things like contains. It's not index optimized.

answered Jan 31, 2022 at 20:17

hunterhacker

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1 Comment

Serhii Hrynko Over a year ago

It is important to note however that you can not use sort key in filter expression. More details here: repost.aws/questions/QUW97JOu44QGWUZehSSw0Mjw/…

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