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ViewsHow to get dynamodb to only return certain columns
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.
2 answers
Answer question0
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.
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table = dynamodb.Table('tablename')
response = table.scan(
AttributesToGet=['id']
)
This works. but this method is deprecated, using Projections is recommended