Cloud Digital Leader Google Cloud Products and Services Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Cloud Spanner

  Why this is correct

  Cloud Spanner is a fully managed, horizontally scalable relational database that combines standard SQL transactions with globally distributed replication. It uses TrueTime (a globally synchronized clock) and Paxos consensus to provide strong external consistency across all regions, meaning reads and writes are always linearizable even during failovers. With a 99.999% availability SLA and the ability to write from any region, it is the only option among these that supports globally consistent relational data at scale.

• ✗

  Firestore in multi-region mode

  Why it's wrong here

  Firestore is a NoSQL document database, so it lacks fundamental relational features like SQL joins, multi-row ACID transactions, and schema enforcement. While multi-region mode replicates data across locations, it does not provide strong consistency across regions; instead, it offers eventual consistency for cross-region reads and writes, meaning a client in one region may read stale data while another region has not yet caught up. For a globally distributed application requiring immediate, consistent relational operations, Firestore's NoSQL model and eventual consistency make it unsuitable.

• ✗

  Cloud SQL with cross-region replication

  Why it's wrong here

  Cloud SQL does support cross-region replication, but it relies on a single primary instance in one region; replicas in other regions are read-only and have a lag, so they cannot accept writes or guarantee strong consistency on failover. The replication is asynchronous, so in a regional outage you can lose recent transactions that were not yet propagated. Additionally, Cloud SQL's availability SLA tops out at 99.99% even with high availability configuration, not the 99.999% you get with Spanner, so it falls short for mission-critical global applications.

• ✗

  Bigtable with replication

  Why it's wrong here

  Bigtable is a wide-column NoSQL database optimized for high-throughput analytics and time-series workloads, not for transactional relational data. It does not support SQL queries, joins, or multi-row transactions, and cross-region replication is eventually consistent, meaning updates made in one cluster can asynchronously lag behind another. While Bigtable is excellent for petabyte-scale analytical workloads, it cannot serve a globally distributed application that demands strong consistency and relational semantics.

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