Google Associate Cloud Engineer

Google Associate Cloud Engineer

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You are managing a globally accessible apparel website using Cloud Spanner. Despite the global reach, you've encountered read latency issues on a specific table accessed solely via its primary key. The table's schema is as follows:

CREATE TABLE Users (
    user_id INT64 NOT NULL, // Sequential number based on registration
    account_creation_date DATE, // System date
    firstname STRING(255), // First name
    lastname STRING(255), // Last name
    birthdate DATE, // User birthdate
    profile_picture BYTES(255) // User profile picture
) PRIMARY KEY (user_id)

What action should you take to mitigate these performance issues?




Explanation:

Correct Answer: C Ensuring the primary key does not have monotonically increasing values can alleviate read latency by preventing hotspotting, where operations concentrate on a few nodes, thus distributing the workload more evenly.

Why Not Others?

  • A: Removing the profile_picture field, a byte type storing binary data like images, doesn't directly improve read latency.
  • B: Adding a secondary index on person_id is ineffective since queries use the primary key, not person_id.
  • D: Creating a secondary index via DDL doesn't address the core issue of primary key access patterns causing latency.

For further reading on schema design and primary key selection in Cloud Spanner, consider these resources: