DynamoDB - Access Patterns and Query Optimization
If a single-table design uses a composite key with PK as 'CUSTOMER#ID' and SK as 'INVOICE#DATE', what will happen if you query with PK='CUSTOMER#123' and SK='INVOICE#2023-01-01'?
If a single-table design uses a composite key with PK as 'CUSTOMER#ID' and SK as 'INVOICE#DATE', what will happen if you query with PK='CUSTOMER#123' and SK='INVOICE#2023-01-01'?
medium📝 query result Q5 of 15
Step-by-Step Solution
Solution:
Step 1: Understand query with exact SK
Querying with exact PK and SK returns the single matching item if it exists.Step 2: Analyze options
Returns the invoice for customer 123 on 2023-01-01 correctly states the result. Returns all invoices for customer 123 would require a range or begins_with on SK. Returns all customers with invoice date 2023-01-01 is invalid because PK is fixed. Returns no results because SK must be a range condition is false; exact SK queries are valid.Final Answer:
Returns the invoice for customer 123 on 2023-01-01 -> Option CQuick Check:
Exact PK and SK query returns one item = D [OK]
Quick Trick: Exact PK and SK returns one item if exists [OK]
Common Mistakes:
MISTAKES- Assuming SK must be a range
- Expecting multiple results with exact SK
- Confusing PK and SK roles
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