PCDE Practice Test 36 — 15 Questions

Question 1

An SRE team wants to automate a manual process that involves multiple steps and conditional logic (e.g., if a backup fails, retry with a different method). Which TWO Google Cloud services can they use to orchestrate this workflow? (Choose 2 answers)

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

Accepted Answer

Cloud Composer. Cloud Composer (B) is correct because it is a managed Apache Airflow service that lets you define multi-step workflows as DAGs with branching, retries, and conditional logic, making it ideal for orchestrating a process like retrying a backup with a different method. Cloud Workflows (D) is also correct because it is a serverless orchestration service that executes YAML/JSON-defined workflows with steps, conditional jumps, and retry/error handling, directly supporting the described conditional logic. Pub/Sub (A) is a messaging service for asynchronous event delivery, not a workflow orchestrator with conditional branching. Cloud Functions (C) is an event-driven compute service for running single-purpose code, not for orchestrating multi-step workflows. Cloud Build (E) is a CI/CD service for building and deploying artifacts, not a general-purpose workflow orchestrator.

Answer

Pub/Sub

Answer

Cloud Functions

Answer

Cloud Build

Question 2

A financial firm uses Cloud Spanner with a single-region configuration. They must meet regulatory requirements for disaster recovery across continents. They need to recover within 1 hour RTO and RPO of 5 minutes. Current workload: 50k writes/sec. What should they do?

Accepted Answer

Use multi-region configuration with synchronous replication across two continents.. Cloud Spanner's multi-region configuration uses synchronous replication across continents, providing strong consistency and automatic failover. This meets the 1-hour RTO and 5-minute RPO requirements for disaster recovery, as synchronous replication ensures data is durable across regions with minimal lag, and Spanner handles failover transparently without manual intervention.

Answer

Use cross-region backups with 5-minute retention.

Answer

Use Cloud SQL for MySQL with cross-region replicas.

Answer

Use export to Cloud Storage every 5 minutes.

Question 3

You need to design a Cloud Bigtable row key for a time-series application that records user activity. The most common queries filter by user_id and then by timestamp (most recent first). Which row key design is MOST appropriate?

Accepted Answer

user_id#reverse_timestamp. The correct row key is user_id#reverse_timestamp because it groups all rows for a given user together (since user_id is the prefix) and, within that group, stores timestamps in reverse order. This allows the most recent events to appear first when scanning the row range for a user, which matches the query pattern of filtering by user_id and retrieving the latest timestamps first. Bigtable sorts row keys lexicographically, so reversing the timestamp ensures that the newest data is at the top of the user's row range, enabling efficient reads without additional sorting or scanning.

Answer

user_id#timestamp

Answer

reverse_timestamp#user_id

Answer

timestamp#user_id

Question 4

You are responsible for a Cloud SQL for MySQL instance that supports a content management system (CMS). The application frequently performs SELECT queries with ORDER BY and LIMIT. Recently, the response time for these queries has increased. The database has 4 vCPUs and 15 GB memory. You check the slow query log and find many queries that are taking over 1 second. The 'rows_examined' is much higher than 'rows_sent'. The EXPLAIN plan shows 'Using filesort' and 'Using temporary'. There is currently an index on the column used in the WHERE clause but not on the ORDER BY columns. The table has 5 million rows. What should you do to improve query performance?

Accepted Answer

Add a composite index on the columns used in the WHERE clause and the ORDER BY clause.. Adding a composite index on the columns used in the WHERE clause and the ORDER BY clause allows MySQL to avoid the expensive 'Using filesort' and 'Using temporary' operations. With a covering index, the database can retrieve rows in the required order directly from the index, eliminating the need to sort the result set after filtering. This dramatically reduces 'rows_examined' and improves query response time for SELECT queries with ORDER BY and LIMIT.

Answer

Increase the buffer pool size to 80% of memory.

Answer

Disable the query cache to reduce overhead.

Answer

Remove the ORDER BY clause and sort the results in application code.

Question 5

You are investigating a performance issue in a distributed application. You want to identify the services causing high latency. Which TWO tools should you use together? (Choose two.)

Accepted Answer

Cloud Trace. Cloud Trace (B) is correct because it collects and analyzes distributed trace data across microservices, showing per-span latency so you can pinpoint which service or RPC call is introducing high latency in the request path. Cloud Profiler (C) is correct because it continuously samples CPU and heap usage of running services, revealing which functions or code paths consume the most resources and thus contribute to latency at the code level. Together they correlate request-level latency (Trace) with code-level hotspots (Profiler), which is exactly what's needed to identify services causing high latency. Error Reporting (A) only aggregates application exceptions and crashes, not latency data. Cloud Logging (D) stores log entries but doesn't provide distributed latency tracing or code profiling. Cloud Monitoring (E) offers metrics, dashboards, and alerting on aggregate signals, but it lacks the per-request trace detail and per-function profiling needed to isolate the specific services and code causing latency.

Answer

Error Reporting

Answer

Cloud Logging

Answer

Cloud Monitoring

Question 6

A company wants to deploy a microservice to Google Cloud. They require canary deployments with automatic rollback if error rate increases. Which TWO services should they use together?

Accepted Answer

Cloud Deploy. Cloud Run (E) is the correct compute platform because it natively supports gradual traffic splitting between revisions via percentage-based traffic allocation, which is exactly what canary deployments require. Cloud Deploy (D) is the correct delivery service because it provides a managed continuous delivery pipeline with progressive rollout strategies (canary and blue/green) and automated rollback/advance based on defined verification criteria such as error-rate thresholds. Together, Cloud Deploy orchestrates the canary rollout and triggers rollback, while Cloud Run serves the revisions and shifts traffic percentages. Cloud Build (A) only builds and pushes container images and does not perform progressive delivery or rollback. Cloud Endpoints (B) is an API management/proxy layer for authentication, quotas, and monitoring, not a deployment orchestrator. Cloud Functions (C) is an event-driven FaaS runtime without native revision-based traffic splitting for canary rollouts.

Answer

Cloud Build

Answer

Cloud Endpoints

Answer

Cloud Functions

Question 7

A Cloud SQL for PostgreSQL instance is used for an OLTP application. The database schema has many foreign key constraints. Which action improves write performance?

Accepted Answer

Create indexes on foreign key columns.. Foreign key constraints require the database to check referential integrity on write operations, which can cause full table scans on the referenced table if the foreign key columns are not indexed. Creating indexes on foreign key columns allows PostgreSQL to quickly verify that a referenced row exists, dramatically reducing the cost of INSERT, UPDATE, and DELETE operations. This is the standard performance optimization for schemas with many foreign keys.

Answer

Drop all foreign key constraints.

Answer

Add more triggers to enforce integrity.

Answer

Increase the instance storage size.

Question 8

A BI team finds that their BigQuery query that aggregates sales by region runs slower than expected, even with appropriate clustering and partitioning. The query filters on a date range and then groups by region. The table is partitioned by date and clustered by region. What can the team do to improve query performance without increasing cost?

Accepted Answer

Use a materialized view that pre-aggregates sales by region and date.. A materialized view in BigQuery can pre-aggregate sales by region and date, allowing the query to read precomputed results instead of scanning the entire table. This reduces the amount of data processed and speeds up the query without increasing cost, as the materialized view is automatically maintained and only incremental changes are processed.

Answer

Increase the number of clusters to include more columns.

Answer

Change the partition type to ingestion-time partitioning.

Answer

Add an ORDER BY clause to the query.

Question 9

A company uses Cloud SQL for SQL Server. They want to store JSON data in a column and query it efficiently. What should they do?

Accepted Answer

Store JSON in an nvarchar(max) column and use JSON_VALUE in queries.. Cloud SQL for SQL Server supports JSON functions like JSON_VALUE to extract and query data from JSON stored in nvarchar(max) columns. This allows efficient querying without schema changes, leveraging SQL Server's built-in JSON support. Option B is correct because it uses the recommended data type and function for JSON storage and querying in SQL Server.

Answer

Store each JSON field as a separate column.

Answer

Use a TEXT column with no indexing.

Answer

Store JSON as a binary column and parse in application.

Question 10

An engineer wants to trigger a Cloud Build pipeline whenever a new pull request(PR) is opened against the 'main' branch of a repository. Which type of build trigger should they configure?

Accepted Answer

Pull Request trigger. A Pull Request trigger in Cloud Build is designed to run builds when a PR is opened, updated, or reopened against a specified branch (e.g., main). It uses the GitHub/GitLab PR webhook and can run checks, tests, or preview deployments before merge. This matches the requirement exactly.

Answer

Manual trigger

Answer

Scheduled trigger (cron)

Answer

Push trigger on branch

Question 11

An engineer is designing a global inventory system that requires strong consistency across continents, with the ability to handle write conflicts and ensure ACID transactions. The system expects millions of reads and writes per second. Which Google Cloud database service meets these requirements?

Accepted Answer

Cloud Spanner. Cloud Spanner is the correct choice because it provides ACID transactions and strong consistency across globally distributed regions, using TrueTime and synchronous replication to handle write conflicts at scale. It is designed for millions of reads and writes per second while maintaining external consistency, making it ideal for a global inventory system.

Answer

Cloud Bigtable

Answer

Cloud SQL

Answer

Firestore

Question 12

Order the steps to export data from Cloud Bigtable to Cloud Storage using Dataflow.

Accepted Answer

First create a Cloud Storage bucket, then set up a Dataflow job using the Bigtable to Cloud Storage template, then configure the job parameters, then run the job, then verify the export.. First create storage, then set up Dataflow job with template, configure, run, verify.

Answer

First set up a Dataflow job using the Bigtable to Cloud Storage template, then create a Cloud Storage bucket, then configure the job, then run the job, then verify.

Answer

First create a Cloud Storage bucket, then configure the Dataflow job, then set up the Dataflow job using the template, then run, then verify.

Answer

First create a Cloud Storage bucket, then set up the Dataflow job using the template, then run the job, then configure the job, then verify.

Question 13

A data analyst needs to run a one-time SQL query on a dataset stored in CSV files in Cloud Storage. The query will scan the entire dataset, and the analyst wants to minimize cost. Which Google Cloud service should they use?

Accepted Answer

BigQuery. BigQuery is the most cost-effective choice for a one-time SQL query on CSV files in Cloud Storage because it supports querying external data directly from Cloud Storage using external tables, and you only pay for the query processing (on-demand pricing). This avoids the need to load data into a database or provision infrastructure.

Answer

Cloud SQL

Answer

Dataproc

Answer

Cloud Spanner

Question 14

A Cloud Spanner database has a table with a primary key and a secondary index. The application frequently queries using a filter on the secondary index column and orders by the primary key. The queries are slow. What should the database administrator do to improve query performance?

Accepted Answer

Create a covering index using CREATE INDEX with the STORING clause to include the required columns. Creating a covering index with the STORING clause lets Cloud Spanner satisfy the query entirely from the index without a back-join to the base table, eliminating the expensive lookup for each row. Because the query filters on the indexed column and orders by the primary key, storing the needed columns in the index makes the index itself sufficient to return results. This directly addresses the slow query by removing the extra read hop.

Answer

Increase the number of nodes to improve query throughput

Answer

Create an interleaved table that mirrors the data

Answer

Use ALTER TABLE to add a new index on the filter column

Question 15

A team uses Cloud Monitoring to create an SLO for a request-based service. They want to alert when the error budget burn rate exceeds 14x the budget for a short window. Which alert type and window should they configure?

Accepted Answer

Fast burn alert with a 1-hour window.. A 14x burn rate over a short window is the classic fast-burn condition in Google SRE multi-window, multi-burn-rate alerting. The fast-burn alert uses a 1-hour lookback window (paired with a 5-minute short window) to detect rapid budget consumption and page immediately, which matches the requirement for a short window.

Answer

Slow burn alert with a 6-hour window.

Answer

Fast burn alert with a 6-hour window.

Answer

Slow burn alert with a 1-hour window.