DynamoDbScan Expression using aws-sdk java

Question

I am using aws-sdk to connect with DynamoDb and I have got into a scenario where I got one dynamodb table with different partition/hash-key and I have to scan and filter to get the results. Scanning the entire table would be a costly operation . Is there a way to scan only a certain partion/haskey of a table ?

Answer 1

You have to use Dynamo DB Query. You can query any table or secondary index that has a composite primary key (a partition key and a sort key).

In my opinion you shouldn't use scan, because it very costly and slow.

You didn't write what is the program language, but here is some example to query:

• https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/DynamoDB.html#query-property

• https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Query.html

• https://www.dynamodbguide.com/querying/

About indices:

• https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/SQLtoNoSQL.Indexes.html

UPDATE #1:

Maybe that will help:

1. Add a new column to your table. The values will be static. (For example: Col name: const_value Values: const)

2. Create a new secondary index to your table.

   • 'partition key': 'const_value'
   • 'sort key': the column what you want to filter

3. You can use Query.