[Solved] You have a DynamoDB table with 1 million items. You need to retrieve all items where the attribute 'Status' equals 'Active'.... Which approach gives the best performance and cost efficiency? | AWS

AWS - DynamoDB

You have a DynamoDB table with 1 million items. You need to retrieve all items where the attribute 'Status' equals 'Active'. The table's primary key is 'UserId'. Which approach gives the best performance and cost efficiency?

AUse Scan with FilterExpression 'Status = Active' to get all matching items

BCreate a Global Secondary Index (GSI) on 'Status' and use Query on the GSI

CUse Query on the primary key 'UserId' with FilterExpression 'Status = Active'

DUse Scan without any filter and filter results in your application code

Step-by-Step Solution

Solution:

Step 1: Understand Scan with filter
Scan reads all 1 million items, filtering after reading, which is slow and costly.
Step 2: Use GSI for efficient querying
Creating a GSI on 'Status' allows Query to directly find 'Active' items efficiently.
Step 3: Evaluate other options
Query on primary key can't filter by 'Status' efficiently; scanning without filter wastes resources.
Final Answer:
Create a Global Secondary Index (GSI) on 'Status' and use Query on the GSI -> Option B
Quick Check:
GSI + Query = best performance for non-key attribute [OK]

Quick Trick: Use GSI and Query for non-key attribute filtering [OK]

Common Mistakes:

Using Scan with filter on large tables
Querying primary key with filter instead of GSI
Filtering in application after full Scan

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Which approach gives the best performance and cost efficiency?

Step 1: Understand Scan with filter

Step 2: Use GSI for efficient querying

Step 3: Evaluate other options

Final Answer:

Quick Check:

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