PCD Practice Test 50 — 15 Questions

Question 1

A data engineer needs to perform complex transformations on streaming data as it moves from Cloud Pub/Sub to Cloud Bigtable. Which service should they use for this purpose?

Accepted Answer

Cloud Dataflow. Dataflow (Apache Beam) is the recommended service for stream processing with complex transformations. It can read from Pub/Sub, apply transformations, and write to Bigtable. Cloud Functions are simpler and not suited for complex ETL.

Answer

Dataproc

Answer

Cloud Run

Answer

Cloud Functions

Question 2

A developer needs to implement caching for a Cloud SQL database to reduce read latency for frequently accessed data. Which Google Cloud service should they use?

Accepted Answer

Memorystore for Redis

Answer

Cloud Spanner

Answer

Cloud CDN

Answer

Cloud Bigtable

Question 3

An organization plans to adopt polyglot persistence: Cloud SQL for transactions, Cloud Bigtable for time-series, and BigQuery for analytics. They need to ensure data consistency when updating both Cloud SQL and Bigtable in a single business transaction. What approach should they use?

Accepted Answer

Implement a saga pattern where each database operation is a local transaction, with compensating actions for failures.

Answer

Use Cloud Spanner for all data to avoid cross-database consistency issues.

Answer

Use a two-phase commit protocol across Cloud SQL and Bigtable.

Answer

Write to Cloud SQL first, then use Cloud Functions to asynchronously write to Bigtable with retries.

Question 4

A company wants to run analytical queries across data stored in Cloud SQL (MySQL), Cloud Storage (Parquet files), and Bigtable without moving any data. Which BigQuery feature enables this?

Accepted Answer

Federated queries using external tables

Answer

BigQuery Omni

Answer

Cloud Data Fusion

Answer

BigQuery BI Engine

Question 5

Your team needs to query data across Cloud SQL (MySQL), Cloud Storage (CSV files), and Bigtable using a single SQL query without moving any data. Which Google Cloud feature enables this?

Accepted Answer

BigQuery federated queries. BigQuery federated queries allow querying data in Cloud SQL, Cloud Storage, Bigtable, and other sources externally via the EXTERNAL_QUERY or table definitions.

Answer

BigQuery Omni

Answer

Cloud Spanner federated queries

Answer

Datastream

Question 6

A financial services company needs to query data across Cloud SQL (PostgreSQL) and BigQuery without moving data. They want to use federated queries from BigQuery to access Cloud SQL tables. What must be created in BigQuery to enable this?

Accepted Answer

A Cloud SQL instance connection. BigQuery federated queries to Cloud SQL require a BigQuery connection (Cloud SQL instance connection) to be created first. This connection stores the credentials and instance details. Then, you use the EXTERNAL_QUERY function in a query to access Cloud SQL tables. An external table is not used for federated queries; it is for querying external data sources like Cloud Storage.

Answer

A BigQuery view

Answer

An external table

Answer

A BigQuery dataset

Question 7

A developer is deploying a new version of a microservice to Cloud Run. The developer wants to ensure that the new revision is tested with a small percentage of traffic before rolling out to all users. Which TWO approaches can the developer use?

Accepted Answer

Use the 'gcloud run deploy' command with '--no-traffic' and then use 'gcloud run services update-traffic --to-revisions=REVISION=5' to send 5% of traffic.. The '--no-traffic' flag deploys the new revision without serving any traffic, and then 'gcloud run services update-traffic --to-revisions=REVISION=5' allows you to send exactly 5% of traffic to that revision for canary testing. Option B is also correct because it describes the same two-step process: deploy with '--no-traffic' to avoid immediate traffic, then use 'update-traffic' to gradually increase the percentage, which is the standard canary deployment pattern on Cloud Run.

Answer

Set the 'max-instances' parameter to limit the number of instances handling requests.

Answer

Use the 'gcloud run deploy' command with '--tag' to assign a tag to the new revision, then direct test traffic to that tag.

Answer

Deploy the new revision with the same revision name as the old one to overwrite it, then roll back if issues occur.

Question 8

A company wants to query data across Cloud SQL (MySQL) and BigQuery using federated queries. They want to avoid data movement. Which TWO components must be set up?

Accepted Answer

External table in BigQuery. A BigQuery connection (external data source) is required to link to Cloud SQL. An external table in BigQuery references the Cloud SQL table for querying. A Cloud SQL instance is the source, but the connection and external table are the components set up in BigQuery.

Answer

Cloud SQL instance

Answer

Cloud Storage bucket

Answer

Dataflow pipeline

Question 9

A retail company wants to run analytics queries across their Cloud SQL PostgreSQL database and BigQuery without moving data. They need to join sales data from Cloud SQL with customer demographics in BigQuery. Which approach should they use?

Accepted Answer

Create a BigQuery external table linked to Cloud SQL. BigQuery federated queries can create an external table that references Cloud SQL PostgreSQL. This allows querying Cloud SQL data directly from BigQuery and joining with BigQuery tables.

Answer

Use BigQuery Omni to query Cloud SQL

Answer

Use Datastream to replicate Cloud SQL to BigQuery

Answer

Export Cloud SQL data to GCS and load into BigQuery

Question 10

A company wants to perform cross-cloud analytics, querying data stored in both Google Cloud BigQuery and Amazon S3. Which BigQuery feature enables this?

Accepted Answer

BigQuery Omni. BigQuery Omni allows querying data across clouds (AWS and Azure) using BigQuery, without moving data.

Answer

Cloud Data Fusion

Answer

BigQuery Data Transfer Service

Answer

BigQuery federated queries

Question 11

A developer needs to query data from Cloud Spanner and Bigtable together in a single SQL statement without moving data. Which Google Cloud feature allows this?

Accepted Answer

Federated queries. BigQuery federated queries allow querying external data sources like Cloud Spanner and Bigtable directly from BigQuery using SQL, without importing data.

Answer

Spanner change streams

Answer

BigQuery Omni

Answer

Cloud SQL external tables

Question 12

An organization has data in Amazon S3 that they want to query from BigQuery without moving it. Which BigQuery feature should they use?

Accepted Answer

BigQuery Omni. BigQuery Omni allows querying data across clouds, including Amazon S3, without moving the data.

Answer

Cloud Storage transfer service to copy data to GCS first

Answer

BigQuery federated queries with AWS Glue

Answer

Bigtable federation

Question 13

A company wants to query data across Cloud SQL, Cloud Spanner, and Bigtable without moving data. They need a solution that supports standard SQL and integrates with their existing business intelligence tools. Which TWO Google Cloud capabilities should they use?

Accepted Answer

BigQuery federated queries. BigQuery federated queries allow you to query Cloud SQL, Cloud Spanner, and Bigtable directly using standard SQL without data movement, making it the correct solution. BigQuery Omni is designed for querying data across AWS and Azure, not for in-GCP databases like Cloud SQL, Cloud Spanner, or Bigtable. Therefore, only option B is correct.

Answer

BigQuery Omni

Answer

Datastream

Answer

Dataflow

Answer

Cloud SQL cross-database queries

Question 14

A company uses Cloud Bigtable for time-series data and wants backups that can be restored in a different region for disaster recovery. Which backup method meets this requirement?

Accepted Answer

Use Bigtable managed backups, which are stored in the same region and can be restored to any cluster. Bigtable managed backups are cluster-level and support cross-cluster restore, including to a different region.

Answer

Export tables to Avro files in GCS, then import in the new region

Answer

Enable replication between Bigtable clusters

Answer

Use BigQuery federated queries to export data to GCS

Question 15

A company is migrating from MySQL 5.7 to Cloud SQL for MySQL 8.0. After migration, a legacy application that uses the 'GROUP BY' clause with implicit sorting stops working correctly. What is the most likely cause?

Accepted Answer

MySQL 8.0 removed the implicit sorting of GROUP BY results.. MySQL 8.0 removed the implicit sorting of GROUP BY that was present in MySQL 5.7. Applications relying on this behavior must explicitly use ORDER BY to guarantee sort order.

Answer

MySQL 8.0 changed the default collation, affecting string comparison.

Answer

MySQL 8.0 no longer supports the 'GROUP BY' clause.

Answer

The 'ONLY_FULL_GROUP_BY' SQL mode is enabled by default.