PCDBE practice questions 31–40

1. Question 31 · 170 in bank

   You are migrating your 2 TB on-premises PostgreSQL cluster to Compute Engine. You want to set up your new environment in an Ubuntu virtual machine instance in Google Cloud and seed the data to a new instance. You need to plan your database migration to ensure minimum downtime. What should you do?

   • A1. Take a full export while the database is offline. 2. Create a bucket in Cloud Storage. 3. Transfer the dump file to the bucket you just created. 4. Import the dump file into the Google Cloud primary server. B.1. Take a full export while the database is offline. 2. Create a bucket in Cloud Storage. 3. Transfer the dump file to the bucket you just created. 4. Restore the backup into the Google Cloud primary server.
   • B1. Take a full backup while the database is online. 2. Create a bucket in Cloud Storage. 3. Transfer the backup to the bucket you just created. 4. Restore the backup into the Google Cloud primary server. 5. Create a recovery.conf file in the $PG_DATA directory. 6. Stop the source database. 7. Transfer the write ahead logs to the bucket you created before. 8. Start the PostgreSQL service. 9. Wait until Google Cloud primary server syncs with the running primary server.
   • C1. Take a full export while the database is online. 2. Create a bucket in Cloud Storage. 3. Transfer the dump file and write-ahead logs to the bucket you just created. 4. Restore the dump file into the Google Cloud primary server. 5. Create a recovery.conf file in the $PG_DATA directory. 6. Stop the source database. 7. Transfer the write-ahead logs to the bucket you created before. 8. Start the PostgreSQL service. 9. Wait until the Google Cloud primary server syncs with the running primary server.

   Show answer

   Answer: C

   Explanation

   Couple of reasons for C option. 1. Database remains online (see link below, and step 1, which says "running master database" 2. Backups are faster then exports (which generates new files) https://cloud.google.com/architecture/migrating-postgresql-to-gcp

   Source: Adapted from community discussion — njda

   References

   • Google Cloud documentation

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2. Question 32 · 170 in bank

   You have deployed a Cloud SQL for SQL Server instance. In addition, you created a cross-region read replica for disaster recovery (DR) purposes. Your company requires you to maintain and monitor a recovery point objective (RPO) of less than 5 minutes. You need to verify that your cross-region read replica meets the allowed RPO. What should you do?

   • AUse Cloud SQL instance monitoring.
   • BUse the Cloud Monitoring dashboard with available metrics from Cloud SQL.
   • CUse Cloud SQL logs.
   • DUse the SQL Server Always On Availability Group dashboard.

   Show answer

   Answer: D

   Explanation

   D. Note, you cannot create a read replica in Cloud SQL for SQL Server unless you use an Enterprise Edition. Which is also a requirement for configuring SQL Server AG. That's not a coincidence. That's how Cloud SQL for SQL Server creates SQL Server read replicas. To find out about the replication, use the AG Dashboard in SSMS. https://cloud.google.com/sql/docs/sqlserver/replication/manage-replicas#promote-replica

   Source: Adapted from community discussion — dynamic_dba

   References

   • Google Cloud documentation

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3. Question 33 · 170 in bank

   You want to migrate an on-premises mission-critical PostgreSQL database to Cloud SQL. The database must be able to withstand a zonal failure with less than five minutes of downtime and still not lose any transactions. You want to follow Google-recommended practices for the migration. What should you do?

   • ATake nightly snapshots of the primary database instance, and restore them in a secondary zone.
   • BBuild a change data capture (CDC) pipeline to read transactions from the primary instance, and replicate them to a secondary instance.
   • CCreate a read replica in another region, and promote the read replica if a failure occurs.
   • DEnable high availability (HA) for the database to make it regional.

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   Answer: D

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4. Question 34 · 170 in bank

   You are migrating an on-premises application to Compute Engine and Cloud SQL. The application VMs will live in their own project, separate from the Cloud SQL instances which have their own project. What should you do to configure the networks?

   • ACreate a new VPC network in each project, and use VPC Network Peering to connect the two together.
   • BCreate a Shared VPC that both the application VMs and Cloud SQL instances will use.
   • CUse the default networks, and leverage Cloud VPN to connect the two together.
   • DPlace both the application VMs and the Cloud SQL instances in the default network of each project.

   Show answer

   Answer: B

   References

   • Google Cloud documentation

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5. Question 35 · 170 in bank

   You recently launched a new product to the US market. You currently have two Bigtable clusters in one US region to serve all the traffic. Your marketing team is planning an immediate expansion to APAC. You need to roll out the regional expansion while implementing high availability according to Google-recommended practices. What should you do?

   • AMaintain a target of 23% CPU utilization by locating: cluster-a in zone us-central1-a cluster-b in zone europe-west1-d cluster-c in zone asia-east1-b
   • BMaintain a target of 23% CPU utilization by locating: cluster-a in zone us-central1-a cluster-b in zone us-central1-b cluster-c in zone us-east1-a
   • CMaintain a target of 35% CPU utilization by locating: cluster-a in zone us-central1-a cluster-b in zone australia-southeast1-a cluster-c in zone europe-west1-d cluster-d in zone asia-east1-b
   • DMaintain a target of 35% CPU utilization by locating: cluster-a in zone us-central1-a cluster-b in zone us-central2-a cluster-c in zone asia-northeast1-b cluster-d in zone asia-east1-b

   Show answer

   Answer: D

   Explanation

   D. The question HA for US and APAC. Any answer which mentions Europe must be wrong. That eliminates A and C. HA requires > 1 cluster, so B must be wrong, leaving D. D shows 2 clusters in US and 2 in APAC.

   Source: Adapted from community discussion — dynamic_dba

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6. Question 36 · 170 in bank

   Your DevOps team is using Terraform to deploy applications and Cloud SQL databases. After every new application change is rolled out, the environment is torn down and recreated, and the persistent database layer is lost. You need to prevent the database from being dropped. What should you do?

   • ASet Terraform deletion_protection to true.
   • BRerun terraform apply.
   • CCreate a read replica.
   • DUse point-in-time-recovery (PITR) to recover the database.

   Show answer

   Answer: A

   Explanation

   A. It makes sense that a Terraform problem would use a Terra form solution. From Google's documentation, "For stateful resources, such as databases, ensure that deletion protection is enabled. The syntax is: lifecycle { prevent_destroy = true } https://cloud.google.com/docs/terraform/best-practices-for-terraform#stateful-resources

   Source: Adapted from community discussion — dynamic_dba

   References

   • Google Cloud documentation

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7. Question 37 · 170 in bank

   Your company's mission-critical, globally available application is supported by a Cloud Spanner database. Experienced users of the application have read and write access to the database, but new users are assigned read-only access to the database. You need to assign the appropriate Cloud Spanner Identity and Access Management (IAM) role to new users being onboarded soon. What roles should you set up?

   • Aroles/spanner.databaseReader
   • Broles/spanner.databaseUser
   • Croles/spanner.viewer
   • Droles/spanner.backupWriter

   Show answer

   Answer: A

   Explanation

   A. Nothing to do with backups. Eliminate D. databaseUser allows read and write. Eliminate B. viewer is at the instance level and does not allow database reads. Eliminate C. Leaves A.

   Source: Adapted from community discussion — dynamic_dba

   References

   • Google Cloud documentation
   • Google Cloud documentation

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8. Question 38 · 170 in bank

   Select 2

   Your company is shutting down their data center and migrating several MySQL and PostgreSQL databases to Google Cloud. Your database operations team is severely constrained by ongoing production releases and the lack of capacity for additional on-premises backups. You want to ensure that the scheduled migrations happen with minimal downtime and that the Google Cloud databases stay in sync with the on-premises data changes until the applications can cut over. What should you do? (Choose two.)

   • AUse an external read replica to migrate the databases to Cloud SQL.
   • BUse a read replica to migrate the databases to Cloud SQL.
   • CUse Database Migration Service to migrate the databases to Cloud SQL.
   • DUse a cross-region read replica to migrate the databases to Cloud SQL.
   • EUse replication from an external server to migrate the databases to Cloud SQL.

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   Answer: CE

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9. Question 39 · 170 in bank

   Your ecommerce website captures user clickstream data to analyze customer traffic patterns in real time and support personalization features on your website. You plan to analyze this data using big data tools. You need a low-latency solution that can store 8 TB of data and can scale to millions of read and write requests per second. What should you do?

   • AWrite your data into Bigtable and use Dataproc and the Apache Hbase libraries for analysis.
   • BDeploy a Cloud SQL environment with read replicas for improved performance. Use Datastream to export data to Cloud Storage and analyze with Dataproc and the Cloud Storage connector.
   • CUse Memorystore to handle your low-latency requirements and for real-time analytics.
   • DStream your data into BigQuery and use Dataproc and the BigQuery Storage API to analyze large volumes of data.

   Show answer

   Answer: A

   Explanation

   A. Cloud SQL could not handle the load, so B is wrong. Memorystore can scale up to 300 GB. The question mentions needing 8 TB, so C must be wrong. BigQuery could not handle the latency requirements of the question, which leaves A. Bigtable could handle the volume of writes at the speeds required.

   Source: Adapted from community discussion — dynamic_dba

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10. Question 40 · 170 in bank

    Select 2

    Your company uses Cloud Spanner for a mission-critical inventory management system that is globally available. You recently loaded stock keeping unit (SKU) and product catalog data from a company acquisition and observed hotspots in the Cloud Spanner database. You want to follow Google-recommended schema design practices to avoid performance degradation. What should you do? (Choose two.)

    • AUse an auto-incrementing value as the primary key.
    • BNormalize the data model.
    • CPromote low-cardinality attributes in multi-attribute primary keys.
    • DPromote high-cardinality attributes in multi-attribute primary keys.
    • EUse bit-reverse sequential value as the primary key.

    Show answer

    Answer: DE

    Explanation

    https://cloud.google.com/spanner/docs/schema-design D because high cardinality means you have more unique values in the collumn. That's a good thing for a hot-spotting issue. E because Spanner specifically has this feature to reduce hot spotting. Basically, it generates unique values https://cloud.google.com/spanner/docs/schema-design#bit_reverse_primary_key

    Source: Adapted from community discussion — juliorevk

    References

    • Google Cloud documentation
    • Google Cloud documentation

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PCDBE practice, question 31. 170 questions available.