DEA-C01 Data Store Management Practice Question
Network Topology
An application uses the 'orders' DynamoDB table with the schema and provisioned throughput shown in the exhibit. The application frequently queries by customer_id (range key) without specifying the order_id (partition key). What is the most likely impact on performance?
⚠ Common exam trap
Watch out — candidates often assume the sort key alone can be used for efficient queries, forgetting that DynamoDB's indexing requires the partition key to be specified for a Query operation.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Queries will require a full table scan, consuming significant read capacity.
The application queries by customer_id (the sort key) without specifying order_id (the partition key). In DynamoDB, a Query operation requires the partition key to be specified; without it, the only way to retrieve items is a full table Scan, which reads every item in the table. This consumes read capacity proportional to the entire table size, leading to high latency and cost.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Queries will require a full table scan, consuming significant read capacity.
Why this is correct
DynamoDB queries must target a single partition key value; omitting order_id forces a Scan across every partition, reading all items and consuming large amounts of provisioned read capacity. The range key alone cannot route the request, so performance degrades proportionally to table size.
- ✗
Queries will be throttled because the table does not have a global secondary index.
Why it's wrong here
Throttling stems from exceeding provisioned read capacity, not from the absence of a GSI; the query simply Scans. It tempts because a GSI on customer_id would enable efficient lookups, making its absence feel causal, yet the direct effect is capacity consumption, not automatic throttling.
- ✗
Queries will be fast because the sort key is indexed.
Why it's wrong here
A sort key is only indexed within its partition, so querying by customer_id alone cannot use it; DynamoDB must Scan every partition. It tempts because range keys do accelerate Query operations when the partition key is also supplied, which is the normal access pattern here.
- ✗
Queries will cause hot partitions on the table.
Why it's wrong here
Hot partitions arise from uneven partition-key distribution or a monotonically increasing key, not from omitting the partition key in a Query. It tempts because inefficient access patterns can concentrate load, but the actual consequence here is a full table Scan consuming read capacity.
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