You are a lead developer working on a new retail system that runs on Cloud Run and Firestore. A web UI requirement is for the user to be able to browse through all products. A few months after go-live

Question

Options

• AModify the query that returns the product list using cursors with limits.
• BCreate a custom index over the products.
• CModify the query that returns the product list using integer offsets.
• DModify the Cloud Run configuration to increase the memory limits.

• A
  80% (45)
• B
  11% (6)
• C
  4% (2)
• D
  5% (3)

Explanation

The root cause is that the application is loading all products from Firestore at once, causing memory exhaustion on Cloud Run during high-traffic periods. Option A - using cursors with limits - implements proper pagination in Firestore. Cursors are the Firestore-recommended way to paginate because they start reading from a specific document position and fetch only a bounded number of results (e.g., 50 products per page). This directly reduces both the memory consumed per request and the total number of expensive Firestore read operations. Option B (custom index) improves query speed but still returns all documents, not reducing memory load. Option C (integer offsets) is discouraged in Firestore because offsets still scan and charge for all preceding documents, providing no memory relief. Option D (increasing memory limits) is a band-aid that addresses the symptom, not the cause, and is explicitly not performance optimization - the question asks to decrease Firestore queries, which D does not do.

No community discussion yet for this question.