CODEWITHSUNDEEP
amazon-web-servicesamazon-dynamodb
Osiris
Osiris

Reputation: 93

Return only the values of an attribute column from a DynamoDB table

Is there a way to return all the values from an attribute (column) in a DynamoDB Table? And does this operation actually have the same computational costs as a ScanAll operation?

I have a large enough table, which I don't intend to return all of of its values, but need only some the values from one of the attributes. I am afraid that if I do a ScanAll operation and then reduce the data, or Query the operational costs will be the same. The workflow as I imagine goes, First, reading all the records receive a blob object and then cutting it to get the attribute in question.

Upvotes: 2

Views: 5142

Answers (1)

baduker
baduker

Reputation: 20042

According to docs: GetItem returns all of the item's attributes. You can use a projection expression to return only some of the attributes.

Having said that, Projection Expression is a string that identifies the attributes that you want. To retrieve a single attribute, specify its name. For multiple attributes, the names must be comma-separated.

aws dynamodb get-item \
    --table-name ProductCatalog \
    --key file://key.json \
    --projection-expression "Description, RelatedItems[0], ProductReviews.FiveStar"

The arguments for --key are stored in the key.json file.

Full docs on that are here.

Upvotes: 1

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