PCD Manage a Solution that Can Span Multiple Database Systems Practice Test 5 — 15 Questions

Question 1

A company wants to use a combination of relational, document, and time-series databases to meet different workload requirements. What is this architectural pattern called?

Accepted Answer

Polyglot persistence. Polyglot persistence is the practice of using multiple database technologies within a single application ecosystem, each chosen for its strengths.

Answer

Database replication

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Multi-cloud database

Answer

Federated querying

Question 2

An organization is migrating an on-premises PostgreSQL database to Cloud SQL. They need minimal downtime and want to use Database Migration Service (DMS) with continuous change data capture (CDC). What is the correct sequence of steps?

Accepted Answer

Create connection profile → start migration job with full dump → CDC phase → promote replica. DMS first creates a connection profile, then starts a migration job performing a full dump, then transitions to CDC, and finally promotes the replica to complete the cutover.

Answer

Create connection profile → start full dump → promote to primary

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Start CDC directly without full dump → promote replica

Answer

Promote replica immediately after creating connection profile

Question 3

You are designing a cross-database solution where Cloud Spanner is the source of truth for transactional data. You need to stream all changes from Spanner to BigQuery for near-real-time analytics. Which approach should you use?

Accepted Answer

Enable Spanner change streams and read directly via Dataflow into BigQuery. Spanner change streams capture row-level changes and can be routed through Pub/Sub to a Dataflow pipeline that writes to BigQuery.

Answer

Set up a trigger in Spanner to call a Cloud Function that inserts into BigQuery

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Configure Datastream to connect to Spanner and replicate to BigQuery

Answer

Use Cloud Scheduler to periodically query Spanner for new rows and insert into BigQuery

Question 4

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 5

A financial services company is implementing a distributed transaction across multiple Cloud Spanner instances in different regions. They require strict ACID compliance. What is the best approach?

Accepted Answer

Use Cloud Spanner with multi-region configuration. Cloud Spanner with a multi-region configuration is the best approach because it provides native support for distributed ACID transactions across regions using synchronous replication and the TrueTime API, ensuring strong consistency, atomicity, and isolation without requiring application-level coordination. This eliminates the complexity and latency of managing distributed transactions manually while meeting strict ACID compliance requirements.

Answer

Use Cloud Pub/Sub to orchestrate eventual consistency

Answer

Use Cloud SQL with cross-region replication and two-phase commit

Answer

Implement a saga pattern with compensating transactions

Question 6

You need to continuously replicate change data from an on-premises Oracle database to BigQuery for real-time analytics. Which Google Cloud service is designed specifically for this purpose?

Accepted Answer

Datastream. Datastream is a Google Cloud serverless change data capture (CDC) and replication service specifically designed to continuously replicate data from sources like Oracle databases to BigQuery. It handles schema drift, supports log-based CDC, and provides low-latency streaming, making it the correct choice for real-time analytics.

Answer

Database Migration Service (DMS)

Answer

Cloud Dataproc

Answer

Dataflow

Question 7

A company wants to use BigQuery to query data stored in AWS S3 without copying it to Google Cloud. Which Google Cloud feature should they use?

Accepted Answer

BigQuery Omni. BigQuery Omni enables querying data in S3 and Azure Blob Storage using a multi-cloud analytics approach.

Answer

Cloud Datastream

Answer

Cloud Storage FUSE

Answer

BigQuery transfers

Question 8

Which Google Cloud database is best suited for high-throughput, low-latency caching to reduce load on a primary database?

Accepted Answer

Memorystore. Memorystore (managed Redis/Memcached) is the caching layer, providing sub-millisecond access times.

Answer

Cloud SQL

Answer

Firestore

Answer

Cloud Bigtable

Question 9

You need to migrate an Oracle database to Cloud SQL for PostgreSQL. The schema must be converted using Oracle to PostgreSQL migration tools. Which tool should you use to automate schema conversion?

Accepted Answer

Ora2Pg. Ora2Pg is an open-source tool for converting Oracle schemas, data, and procedures to PostgreSQL.

Answer

Cloud Dataflow

Answer

pg_dump

Answer

Database Migration Service (DMS)

Question 10

You need to back up a Cloud Spanner database and store it in a different region for disaster recovery. The backup should be a full database export. What is the recommended method?

Accepted Answer

Use the gcloud command to export the database to Cloud Storage as Avro. The recommended method for backing up a Cloud Spanner database for disaster recovery is to use the `gcloud` command to export the database to Cloud Storage in Avro format. This creates a full database export that can be stored in a different region, enabling restoration in case of a regional failure. Cloud Spanner does not support native backup to other regions; instead, you must export the data to Cloud Storage and then import it into a new instance in the target region.

Answer

Use pg_dump to export Spanner data

Answer

Use Bigtable managed backups

Answer

Use Cloud SQL automated backups

Question 11

A company has an application using Cloud SQL MySQL and wants to add a caching layer. They also need the cache to persist data across restarts. Which Memorystore tier should they choose?

Accepted Answer

Memorystore for Redis Standard tier. Memorystore for Redis Standard tier is the correct choice because it provides replication (a replica node) and automatic failover, which enables data persistence across restarts. Unlike the Basic tier, which is a single node with no persistence guarantees, the Standard tier uses append-only file (AOF) persistence to ensure data survives node restarts. This meets the requirement for a caching layer that persists data across restarts.

Answer

Memorystore for Redis Basic tier

Answer

Memorystore for Memcached

Answer

Cloud Bigtable

Question 12

Which service provides serverless change data capture (CDC) from MySQL and PostgreSQL to BigQuery or Cloud Storage without writing code?

Accepted Answer

Datastream. Datastream is a serverless CDC service that can stream changes to BigQuery, Cloud Storage, or Pub/Sub.

Answer

BigQuery Data Transfer Service

Answer

Cloud Functions

Answer

Dataflow

Question 13

Which TWO Google Cloud services can be used to build a data pipeline that transforms and moves data between different databases? (Select 2)

Accepted Answer

Dataflow. Dataflow is a serverless, fully managed service for executing Apache Beam pipelines, which can read from and write to various databases (e.g., Cloud Spanner, BigQuery, Cloud SQL) while performing transformations in a unified streaming or batch model. It is specifically designed for data movement and transformation between different data sources and sinks, making it a correct choice for building a data pipeline that transforms and moves data between databases.

Answer

Cloud Scheduler

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Memorystore

Answer

Cloud SQL Proxy

Question 14

A company is using Datastream to replicate data from an on-premises PostgreSQL database to BigQuery. They encounter high latency in replication. Which THREE steps should they take to improve performance? (Select 3)

Accepted Answer

Enable parallel processing in Datastream source configuration. Option B is correct because enabling parallel processing in the Datastream source configuration allows multiple threads to read from the PostgreSQL database simultaneously, reducing the time to capture and stream changes. This directly addresses high latency by increasing throughput from the source, leveraging PostgreSQL's logical replication slots more efficiently.

Answer

Switch to a larger Datastream machine type

Answer

Reduce the retention period of the PostgreSQL WAL logs

Question 15

An application uses Cloud SQL MySQL for OLTP and wants to run analytics queries without impacting performance. Which TWO approaches can achieve this? (Select 2)

Accepted Answer

Use BigQuery federated queries to query Cloud SQL directly. Option A is correct because BigQuery federated queries allow you to query Cloud SQL MySQL in real time using BigQuery's SQL engine, without moving data. This enables analytics on live OLTP data while offloading the query processing to BigQuery, thus avoiding performance impact on the Cloud SQL instance. Option C is correct because a Cloud SQL read replica is a separate read-only copy of the primary instance; running analytics queries on the replica prevents resource contention with OLTP write operations.

Answer

Use Cloud Spanner for OLTP instead

Answer

Use BigQuery Omni

Answer

Enable Cloud SQL automatic storage increase