PCD Practice Test 13 — 15 Questions

Question 1

You want to configure Cloud SQL for MySQL with high availability (HA). The application requires that failover be automatic and that the failover replica is in a different zone within the same region. Which configuration should you use?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Enable the high availability option when creating the Cloud SQL instance. Enabling the high availability (HA) option when creating a Cloud SQL for MySQL instance automatically provisions a standby replica in a different zone within the same region. This configuration provides automatic failover without manual intervention, meeting the requirement for HA with zone-level redundancy.

Answer

Use Cloud SQL with a cross-region replica and configure failover with gcloud

Answer

Set up a Cloud SQL instance with multiple read replicas and use failover via the Cloud SQL Proxy

Answer

Create a read replica in a different zone and configure automatic failover using a load balancer

Question 2

During an Oracle to PostgreSQL migration using Ora2Pg, a developer notices that PL/SQL packages are not being converted correctly. What is the recommended strategy to handle Oracle packages in PostgreSQL?

Accepted Answer

Recreate each procedure/function as a separate function in a dedicated schema, and use temporary tables for package variables.. PostgreSQL does not have a direct equivalent of Oracle packages. The recommended approach is to convert package procedures and functions to individual functions in a schema, and package variables to session-level variables or temporary tables. Ora2Pg can attempt conversion but often requires manual adjustments.

Answer

Use pglogical to replicate Oracle data to PostgreSQL and rewrite application code to call PostgreSQL functions directly.

Answer

Keep the Oracle database as a read replica and use Oracle Foreign Data Wrapper for PostgreSQL.

Answer

Use PostgreSQL's CREATE PACKAGE extension (available in some forks) to maintain package structure.

Question 3

Your application uses Cloud Spanner with strong reads, but you are experiencing high latency for read requests. You don't need absolute consistency for every read; stale data up to 5 seconds is acceptable. How can you reduce read latency?

Accepted Answer

Use bounded staleness reads with a max staleness of 5 seconds. Bounded staleness reads let you specify a maximum staleness (e.g., 5 seconds), so Spanner can serve the read from the nearest replica without waiting for the latest committed data. This dramatically reduces latency because the read does not have to round-trip to the leader or wait for replication, while still guaranteeing data is no more than 5 seconds old.

Answer

Use the read timestamp to read the latest data

Answer

Create a global secondary index on frequently read columns

Answer

Use DML instead of mutations for writes

Question 4

A mobile app needs to store user preferences and allow offline read-write sync when the device reconnects. The data is simple key-value pairs. Which Google Cloud database is MOST suitable?

Accepted Answer

Firestore. Firestore is a serverless, document-oriented NoSQL database designed for mobile and web apps, with native SDKs that support offline persistence and automatic synchronization when connectivity returns. Its document model handles simple key-value preference data efficiently, and it scales automatically without provisioning. This makes it the natural fit for a mobile app needing offline read-write sync.

Answer

Memorystore for Redis

Answer

Cloud Bigtable

Answer

Cloud SQL

Question 5

Which three of the following are managed database services offered by Google Cloud that support SQL or SQL-like query languages? (Choose 3)

Accepted Answer

AlloyDB. Cloud SQL, Cloud Spanner, and AlloyDB all support SQL. Bigtable uses HBase API, not SQL. Memorystore is a cache, not a database with SQL.

Answer

Memorystore

Answer

Cloud Bigtable

Question 6

A team is performing a shadow writes testing strategy as part of database migration validation. What does this involve?

Accepted Answer

Duplicating all writes to both source and target databases and comparing. Shadow writes testing involves duplicating every write operation from the source database to the target database simultaneously, then comparing the results to validate that the target handles the same workload identically. This is a core technique in database migration validation because it exercises the target with real production write patterns rather than synthetic test data. The comparison of both databases after the shadow period reveals discrepancies in data types, constraints, triggers, or stored procedures that would otherwise surface only after cutover.

Answer

Creating a snapshot of the source database

Answer

Running comparison queries after migration

Answer

Writing test data only to the new database

Question 7

A web application hosted on Compute Engine is experiencing slow response times during peak hours. Which Cloud Monitoring metric should be examined first to identify the bottleneck?

Accepted Answer

95th percentile request latency measured by Cloud Load Balancing. The 95th percentile request latency measured by Cloud Load Balancing is the most direct indicator of user-perceived performance degradation. High latency at the load balancer level captures the end-to-end response time, including network, backend processing, and queuing delays, making it the first metric to examine when diagnosing slow response times during peak hours.

Answer

CPU utilization of backend instances

Answer

Number of incoming requests per second

Answer

Memory usage of backend instances

Question 8

A company is migrating an on-premises PostgreSQL database to Cloud SQL for PostgreSQL using Database Migration Service (DMS). They need to minimize downtime during the cutover. What should they do to achieve a zero-downtime cutover?

Accepted Answer

Create a continuous migration job, let it replicate changes, then promote the Cloud SQL replica to primary.. Database Migration Service (DMS) supports continuous migration jobs that use PostgreSQL logical replication to keep the Cloud SQL replica synchronized with the on-premises source. When you are ready to cut over, you promote the Cloud SQL replica to a standalone primary, which applies any remaining changes and makes the database available with minimal downtime — typically only seconds for the final replication lag to clear.

Answer

Set up VPC peering between on-premises and Cloud SQL, then use pg_dump and pg_restore.

Answer

Use Cloud SQL Auth Proxy to connect and manually copy data using a script.

Answer

Create a one-time migration job and stop the source database during the migration.

Question 9

Which TWO are benefits of using Cloud Build for your CI/CD pipeline?

Accepted Answer

Built-in integration with Cloud Source Repositories, GitHub, and Bitbucket.. Option A is correct because Cloud Build natively integrates with source repositories such as Cloud Source Repositories, GitHub, and Bitbucket, allowing triggers to automatically start builds on commits or pull requests without custom webhook plumbing. Option D is correct because Cloud Build is a fully managed CI/CD service: Google provisions and scales the build workers, so you don't manage servers, patching, or capacity for build execution. Option B is wrong because Cloud Build offers a limited free tier (e.g., a set number of free build-minutes per day on the standard machine type), not unlimited free minutes. Option C is wrong because Cloud Build is language-agnostic, running builds in containers and supporting many languages and ecosystems via build steps and community builders. Option E is wrong because Cloud Build provides managed execution and a large library of prebuilt builders, so test runners generally don't require manual setup of underlying infrastructure.

Answer

Provides unlimited free build minutes per day.

Answer

Supports only Java and Python.

Answer

Requires manual setup for all test runners.

Question 10

A team runs a microservice on Compute Engine behind a regional external HTTP load balancer. They want to automatically replace unhealthy instances without manual intervention. Which feature should they use?

Accepted Answer

Managed instance group with autoscaling and health check. A managed instance group (MIG) with autoscaling and a health check is the correct choice because it automatically replaces unhealthy instances based on the health check results. The MIG uses the health check to detect failed instances, then automatically recreates them from the instance template, ensuring high availability without manual intervention. Autoscaling further adjusts the number of instances based on load, but the core replacement mechanism is driven by the MIG's health check and autohealing feature.

Answer

Unmanaged instance group with health check

Answer

Instance template with manual replacement

Answer

Load balancer backend service health check only

Question 11

A company is migrating an on-premises Oracle database to Cloud SQL for PostgreSQL. They need to assess the compatibility of the existing schema and identify objects that need conversion. Which tool should they use?

Accepted Answer

Ora2Pg. Ora2Pg is an open-source tool specifically designed to migrate Oracle databases to PostgreSQL. It connects to Oracle, extracts schema and data, and generates PostgreSQL-compatible DDL and DML, including assessment reports that identify incompatible objects (PL/SQL packages, sequences, data types) requiring conversion. This is exactly what the question asks for.

Answer

gcloud sql import

Answer

Database Migration Service (DMS)

Answer

Cloud Dataflow

Question 12

A startup wants to use Firestore for a mobile app. They need to restrict access so that users can only read and write their own data. Which Firestore security rule feature should they use?

Accepted Answer

Use request.auth to get the user's UID and compare it to the document's owner field.. Firestore security rules use `request.auth` to identify the authenticated user and `resource.data` to access document fields. Combining these allows rules to compare the user ID in the request with the document’s owner field. `get()` and `exists()` are functions for cross-document validation, not for user identity.

Answer

Use Firebase Authentication and enable anonymous sign-in.

Answer

Set up IAM roles for each user.

Answer

Use the get() function to retrieve the user's document each time.

Question 13

An application running on GKE is experiencing high latency. The team uses Cloud Trace to identify the bottleneck. They notice that a particular service spends most of its time waiting on a database query. How can they optimize performance?

Accepted Answer

Optimize the database query and add appropriate indexes. The bottleneck is identified as a database query causing high latency. Optimizing the query and adding appropriate indexes directly reduces the time spent waiting on the database, which is the root cause. Cloud Trace shows the service is waiting on the database, so improving database performance is the most effective solution.

Answer

Decrease the number of pods to reduce load

Answer

Use Cloud CDN to cache database results

Answer

Increase the number of replicas for the service

Question 14

A team is deploying a critical application on Google Kubernetes Engine (GKE) and needs to ensure high availability and disaster recovery. Which THREE actions should they take?

Accepted Answer

Use a regional cluster with control plane replicated across zones.. A regional cluster in GKE replicates the control plane across multiple zones within a region, ensuring that if one zone fails, the control plane remains available. This is essential for high availability and disaster recovery, as it eliminates a single point of failure for cluster management operations.

Answer

Deploy all pods in a single zone for simplicity.

Answer

Use a zonal cluster to reduce costs.

Question 15

An application running on GKE needs to access a Cloud SQL instance. The team wants to avoid using Cloud SQL Auth Proxy to reduce complexity. What is the most secure alternative?

Accepted Answer

Use Private Service Connect to connect privately.. Private Service Connect (PSC) allows your GKE cluster to connect to Cloud SQL privately using internal IPs within the same VPC, without exposing traffic to the public internet or requiring the Cloud SQL Auth Proxy. PSC creates a private endpoint that routes traffic through Google's internal network, providing secure, low-latency connectivity while reducing operational overhead.

Answer

Whitelist the GKE node external IPs in Cloud SQL authorized networks.

Answer

Use a Cloud SQL read replica with a public IP.

Answer

Configure Cloud SQL to allow all traffic from the VPC.