How to get dynamodb to only return certain columns

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Hello, I have a simple dynamodb table here filled with placeholder values.

How would i go about retrieving only sort_number, current_balance and side with a query/scan?

I'm using python and boto3, however, just stating what to configure for each of the expressions and parameters is also enough.

amazon-dynamodb boto3 amazon-web-services python
2 Answers

Within the Boto3 SDK you can use:

  • get_item if you're trying to retrieve a specific value
  • query, if you're trying to get values from a single partition (the hash key).
  • scan if you're trying to retrieve values from across multiple parititions.

Each of these have a parameter named ProjectionExpression, using this parameter provides the following functionality

A string that identifies one or more attributes to retrieve from the specified table or index. These attributes can include scalars, sets, or elements of a JSON document. The attributes in the expression must be separated by commas.

]You would specify the attributes that you want to retrieve comma separated, be aware that this does not reduce the cost of RCU that is applied for performing the interaction.

user_134609330 
   table = dynamodb.Table('tablename')
   response = table.scan(
        AttributesToGet=['id']

        )

This works. but this method is deprecated, using Projections is recommended

user_17529170
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