如何使用查询从DynamoDb中的表获取所有记录

Question

Newbie to DynamoDb

I have a table in AWS DynamoDb as below

tblCustomer

Id Name Email
1  Abc  abc@gmail.com
2  Xyz  xyz@gmail.com

It's a huge table. While exploring on around it. Query is better than Scan . So I chose Query over Scan.

This is how my C# function looks like.

AmazonDynamoDBClient client = new AmazonDynamoDBClient();

var request = new QueryRequest
{
 TableName = "tblCustomer",
 ProjectionExpression = "Name, Email"
 };

 var response = await client.QueryAsync(request);

 foreach (Dictionary<string, AttributeValue> item in response.Items)
 {

 }

But this is throwing the exception

KeyConditionExpress cannot be null

Here I don't need to have KeyConditionExpress as I need to get all the customers.

How can I get all the records from tblCustomer in most efficient way?

Thanks!

Answer 1

A query is better than a scan if you are looking to return a subset of the records - what you are trying to do (a query with no conditions) is the functional equivalent of a scan anyway, so you might as well use the scan.

That said, if you find yourself needing to run full-table scans often, it might indicate a problem with your design - scans are expensive and slow and should be used only when necessary.