Given a DynamoDB table with primary key { PartitionKey: 'CustomerId', SortKey: 'OrderDate' }, which query will efficiently retrieve all orders for customer '123' sorted by date?
medium📝 query result Q13 of 15
DynamoDB - Access Patterns and Query Optimization
Given a DynamoDB table with primary key { PartitionKey: 'CustomerId', SortKey: 'OrderDate' }, which query will efficiently retrieve all orders for customer '123' sorted by date?
Query uses keys to efficiently find items; scan reads entire table and filters after.
Step 2: Match query to access pattern
Query(TableName='Orders', KeyConditionExpression='CustomerId = :cid', ExpressionAttributeValues={':cid': '123'}) queries by partition key 'CustomerId' = '123', which is efficient and returns sorted by 'OrderDate'.
Final Answer:
<code>Query(TableName='Orders', KeyConditionExpression='CustomerId = :cid', ExpressionAttributeValues={':cid': '123'})</code> -> Option C
Quick Check:
Query by partition key = efficient retrieval [OK]
Quick Trick:Use Query with partition key, not Scan, for fast results [OK]
Common Mistakes:
MISTAKES
Using Scan instead of Query for key-based retrieval
Querying by sort key alone without partition key
Not using KeyConditionExpression properly
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