PCDE Practice Test 38 — 15 Questions

Question 1

A company's Cloud Spanner database currently uses a regional configuration in us-central1. Due to growth, the database must support global reads with low latency and maintain strong consistency. The database engineer is evaluating options. Which THREE considerations should the engineer include in the design? (Choose three.)

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

Accepted Answer

Select a configuration that places the leader region close to the majority of write traffic.. In a multi-region Cloud Spanner configuration, the leader region handles all writes and must be placed close to the majority of write traffic to minimize write latency. This ensures strong consistency, as all reads are served from the same leader region by default, and global reads with low latency require careful leader placement to avoid cross-region round trips.

Answer

Use interleaved tables to reduce the number of reads required for hierarchical data.

Answer

Add read replicas in remote regions to serve reads with eventual consistency.

Question 2

A company wants to set up cost tracking by project, environment, and team. Which THREE methods should they use? (Choose 3)

Accepted Answer

Set up budget alerts to monitor spending.. Option D is correct because applying labels to resources with keys such as project, environment, and team is the fundamental Google Cloud mechanism for attributing costs to those dimensions; labels flow into billing data and can be used to filter and group costs in reports and exports. Option B is correct because exporting billing data to BigQuery provides the granular, queryable dataset needed to analyze costs by label across projects, environments, and teams, enabling custom joins and long-term reporting beyond the built-in console. Option A is correct because budget alerts monitor spending against defined thresholds and, when scoped with filters such as labels or projects, notify the right stakeholders when costs for a project, environment, or team approach or exceed budget. Option C is not correct because Cloud Monitoring dashboards are for operational metrics like CPU, latency, and uptime, not for cost tracking or billing analysis. Option E is not correct because network tags are used for firewall rules, routing, and VM network configuration, not for cost attribution or billing reports.

Answer

Use Cloud Monitoring dashboards for billing.

Answer

Use network tags for cost tracking.

Question 3

An SRE team uses PagerDuty for on-call rotation. They receive a critical alert at 2 AM. According to incident management best practices, what should the on-call engineer do first?

Accepted Answer

Acknowledge the alert and begin triage according to the runbook. Incident management best practice (ITIL, SRE) dictates that the on-call engineer first acknowledges the alert to stop escalation and then begins triage following the runbook. Acknowledging prevents the alert from escalating to the next on-call and signals ownership; triage determines severity and next steps. This is the standard first action.

Answer

Ignore it until morning because it's off-hours

Answer

Start a postmortem immediately

Answer

Immediately escalate to the incident commander

Question 4

A financial services company is migrating its on-premises Oracle database to Cloud SQL for PostgreSQL. The database contains many PL/SQL packages and stored procedures. They plan to use the Google Cloud Database Migration Service (DMS) for the migration. However, DMS does not automatically convert PL/SQL code. Which approach should they take to ensure that the business logic is properly migrated and continues to function after the migration?

Accepted Answer

Use Ora2Pg to convert PL/SQL to PL/pgSQL, then manually review and adjust the converted code.. Ora2Pg is a specialized tool that automates the conversion of Oracle PL/SQL to PostgreSQL PL/pgSQL. While it handles much of the syntax translation, manual review is essential to address semantic differences and ensure the converted code behaves correctly. Using Ora2Pg aligns with best practices for migrating Oracle business logic to Cloud SQL for PostgreSQL, as it reduces manual effort and provides a structured conversion process.

Answer

Migrate the PL/SQL code as-is by creating wrapper functions in PostgreSQL that call external Oracle procedures.

Answer

Enable the Oracle compatibility mode in Cloud SQL for PostgreSQL to run PL/SQL directly.

Answer

Use the Database Migration Service's built-in PL/SQL to PL/pgSQL converter during the migration.

Question 5

Refer to the exhibit. What is the effect of the partition_expiration_days option?

Accepted Answer

Partitions older than 365 days are automatically deleted. The `partition_expiration_days` option in BigQuery automatically drops partitions that are older than the specified number of days, reducing storage costs and simplifying lifecycle management. When set to 365, any partition with a date older than 365 days from the current date is deleted by BigQuery's background maintenance process.

Answer

The table's storage cost is reduced by 365%

Answer

Queries that reference data older than 365 days will fail

Answer

The table will be partitioned into 365 partitions

Question 6

A company has a BigQuery table that stores JSON data in a single column. They want to allow BI analysts to query nested fields using standard SQL. What is the best approach to make the data more query-friendly for BI tools?

Accepted Answer

Unnest the JSON into multiple columns using a persistent table with a flattened schema.. Flattening the JSON into a persistent table with a normalized schema eliminates the need for runtime parsing, allowing BI tools to query nested fields directly with standard SQL. This approach improves query performance by avoiding repeated JSON function calls and enables the use of indexed columns, which is critical for interactive BI workloads.

Answer

Use BigQuery's automatic schema detection to infer the structure.

Answer

Create a view that uses JSON_QUERY and JSON_VALUE functions to expose nested fields as columns.

Answer

Use the EXTRACT function to parse JSON fields in each query.

Question 7

You need to monitor a critical batch job that runs daily on Compute Engine. If the job does not complete within 2 hours, you want to be paged via PagerDuty. The job emits a custom metric 'batch_duration' as a GAUGE that records the duration of the last completed run. What alerting policy condition should you use?

Accepted Answer

Metric absent condition: with duration of 2 hours on the 'batch_duration' metric.. The 'batch_duration' metric is a GAUGE that only updates when a run completes. If the job hangs and never completes, the metric stops being written, so a metric-absent condition with a 2-hour duration will fire — detecting the missing completion. A threshold condition would only fire after a completed run exceeded 2 hours, which is too late for paging on a stuck job.

Answer

Forecast condition: predict that duration will exceed 2 hours.

Answer

Log-based metric alert: count log entries indicating job failure.

Answer

Metric threshold condition: threshold > 7200 (seconds) on the 'batch_duration' metric.

Question 8

Which database service should you use if your workload requires complex JOINs, ACID transactions, and you want to avoid operational overhead of managing patching and backups?

Accepted Answer

Cloud SQL. Cloud SQL is the correct choice because it is a fully managed relational database service that supports complex JOINs, ACID transactions, and handles patching, backups, and replication automatically. It is designed for traditional relational workloads that require strong consistency and SQL support without operational overhead.

Answer

Cloud Bigtable

Answer

Firestore

Answer

Cloud Storage

Question 9

A company is migrating on-premises MySQL databases to Cloud SQL. They need to ensure high availability and disaster recovery with minimal data loss. Which TWO configurations should they implement?

Accepted Answer

Enable High Availability (HA) configuration on the primary instance.. Enabling High Availability (HA) configuration on a Cloud SQL primary instance creates a synchronous standby in a different zone within the same region, providing automatic failover with minimal data loss (typically under one second) during a zonal outage. For disaster recovery across regions, a cross-region read replica provides an asynchronous copy that can be promoted to a primary if the original region becomes unavailable; while it has a higher RPO than HA, it is the recommended Cloud SQL mechanism for cross-region DR. Together, HA covers zonal high availability and the cross-region read replica covers regional disaster recovery.

Answer

Configure automated backups with 7-day retention.

Answer

Use Cloud SQL Proxy for secure connections.

Answer

Enable binary logging for point-in-time recovery.

Question 10

An engineer is managing a Cloud Spanner database and needs to add a new column to an existing table without downtime. Which approach should be used?

Accepted Answer

Use ALTER TABLE ADD COLUMN statement. In Cloud Spanner, adding a new column to an existing table without downtime is achieved using the ALTER TABLE ADD COLUMN statement. This DDL operation is applied online, meaning the table remains fully available for reads and writes during the schema change, with no need for data migration or table recreation.

Answer

Export the database, modify the schema, and import using Dataflow

Answer

Use CREATE INDEX for the new column

Answer

Drop and recreate the table with the new column

Question 11

A company uses Cloud Spanner for a global inventory system. They need to add a new index on an existing table to support a new query pattern without downtime. What is the correct approach to create the index?

Accepted Answer

Use the gcloud CLI to create the index; Spanner handles it as an online, non-blocking operation. Cloud Spanner supports online schema changes, including index creation, without requiring downtime. When you use the gcloud CLI or the Cloud Console to create an index, Spanner performs the operation as a non-blocking, asynchronous background process that allows continued reads and writes on the table.

Answer

Create a new table with the index and migrate data manually

Answer

Use the Cloud Console to create the index; it requires a maintenance window

Answer

Take the table offline, create the index, then bring it back online

Question 12

A company is using Memorystore for Redis and needs to persist data across restarts. Which option should they use?

Accepted Answer

Take periodic snapshots and store them in Cloud Storage. Memorystore for Redis automatically persists data using RDB snapshots; this is built into the service and does not require the user to take snapshots or store them in Cloud Storage. Memorystore does not support AOF persistence, and there is no 'auto-backup' feature. Because persistence is automatic, the question's premise that the company must choose an option to persist data is misleading. A corrected question should either ask about the built-in persistence mechanism or clarify that no additional configuration is needed.

Answer

Enable AOF persistence in Memorystore settings

Answer

Use a standard tier instance with persistence enabled

Answer

Enable auto-backup in Memorystore

Question 13

A team is migrating a PostgreSQL database to AlloyDB using DMS with continuous replication. After starting the migration job, the initial dump completes but CDC replication fails with a replication slot error. What is the most likely cause?

Accepted Answer

The wal_level parameter on the source is set to 'replica' instead of 'logical'.. The initial dump completes successfully because it uses a snapshot and does not require logical replication. However, for the CDC (change data capture) phase, DMS relies on logical replication slots to capture ongoing changes. This requires the source PostgreSQL database to have its wal_level parameter set to 'logical'. If it is set to 'replica' (the default), the write-ahead log does not contain the necessary information for logical replication, causing DMS to fail when trying to create or use the replication slot. Therefore, option A is correct.

Answer

The source database does not have the pglogical extension installed.

Answer

The destination AlloyDB cluster has insufficient storage capacity.

Answer

The DMS connection profile uses the wrong user credentials.

Question 14

Which TWO strategies reduce query costs for ad-hoc analysis in BigQuery? (Choose two.)

Accepted Answer

Use clustered tables on frequently filtered columns.. Clustered tables in BigQuery physically sort data based on the specified columns, which allows the query engine to skip entire blocks of data that don't match filter predicates. This reduces the amount of data scanned and thus lowers query costs for ad-hoc analysis. Option E is correct because materialized views precompute and store the results of common aggregations, so queries against them only read the precomputed results rather than scanning the base table, significantly reducing bytes processed.

Answer

Use LIMIT 10 to preview data.

Answer

Use a flat table without partitioning.

Answer

Use SELECT * in all queries.

Question 15

An application running on GKE uses OpenTelemetry for instrumentation. You need to export traces to Cloud Trace and custom metrics to Cloud Monitoring. Which approach is most efficient?

Accepted Answer

Use the OpenTelemetry Collector to receive OTLP data and export to Cloud Trace and Cloud Monitoring. The OpenTelemetry Collector is the vendor-neutral pipeline component that receives OTLP data from instrumented applications and fans it out to multiple backends via configured exporters. Running a single collector (as a sidecar, DaemonSet, or Deployment on GKE) lets the app emit one OTLP stream while the collector routes traces to Cloud Trace and metrics to Cloud Monitoring. This decouples the application from backend-specific SDKs and avoids duplicating export logic in code.

Answer

Write a custom exporter in the application that sends data to both services

Answer

Export traces to Cloud Trace via Stackdriver Trace exporter and metrics to Cloud Monitoring via Stackdriver Metrics exporter in the SDK

Answer

Configure the OpenTelemetry SDK to export directly to Cloud Trace and Cloud Monitoring endpoints