PCDE Migrate data solutions Practice Test 3 — 15 Questions

Question 1

A team is planning a migration from PostgreSQL to Cloud SQL with minimal downtime. They have set up DMS continuous migration. At cutover time, they need to ensure no data loss. What should they verify before promoting the destination?

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

Accepted Answer

The DMS replication lag is 0 seconds. Before promoting the destination in a DMS continuous migration, the critical check is that replication lag is 0 seconds (or effectively zero), meaning the destination has fully caught up with the source and no transactions remain unapplied. Promoting while lag is nonzero risks losing the writes that were still in flight. DMS exposes this via the CDC replication lag metric, and cutover should only proceed once it stabilizes at zero.

Answer

The DMS job status is 'Running'

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The destination has been promoted already

Answer

The source database is still accepting writes

Question 2

An organization is migrating a Redshift data warehouse to BigQuery using BigQuery Data Transfer Service. They have scheduled a recurring transfer. However, they notice that some columns are not being mapped correctly. What is the most likely cause?

Accepted Answer

Incorrect column mapping configuration. The most likely cause of columns not mapping correctly during a recurring BigQuery Data Transfer Service transfer from Redshift is an incorrect column mapping configuration. The transfer service relies on the mapping defined during setup, and if it doesn't match the source schema, columns will be misaligned or omitted.

Answer

Insufficient BigQuery permissions

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Source column order differs from destination

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Transfer schedule is too frequent

Question 3

After promoting a Cloud SQL destination in a DMS continuous migration, the application team updates the connection strings. However, they want a rollback plan in case issues arise. What should they keep running to allow a rollback?

Accepted Answer

Keep the source database running in read-only mode. To preserve a rollback option after promoting the Cloud SQL destination, the source database must remain running and in read-only mode so it stays consistent and can be re-promoted if needed. Keeping the source read-only prevents new writes that would diverge from the destination, and keeping it running means the data is still available for a reverse cutover. This is the standard DMS rollback posture after a continuous migration promotion.

Answer

Keep both databases writable

Answer

Keep the destination database in read-only mode

Answer

Keep the DMS job active

Question 4

Which TWO actions should be performed during cutover planning for a DMS continuous migration to minimize downtime?

Accepted Answer

Quiesce writes to the source database. Option A (Quiesce writes to the source database) is correct because during cutover you must stop new write traffic to the source so that no further changes are generated; this allows the ongoing DMS replication to drain the remaining changes and prevents data divergence between source and target. Option C (Confirm DMS replication lag is 0) is correct because the cutover should only proceed once the AWS DMS task's CDCLatencySource and CDCLatencyTarget (or the replication lag metric) show zero, meaning all source changes have been applied to the target and the destination is fully caught up. Option B (Drop the source database) is wrong because dropping the source is destructive and unnecessary for cutover; the source is typically retained for rollback and decommissioned only after validation. Option D (Update application connection strings to the destination) is a post-cutover step performed after replication has drained and the target is validated, not part of the pre-cutover planning actions to minimize downtime. Option E (Create a new DMS migration job) is wrong because a new job would restart full load/replication rather than leverage the existing continuous replication task already keeping the target in sync.

Answer

Drop the source database

Answer

Update application connection strings to the destination

Answer

Create a new DMS migration job

Question 5

A company is migrating from PostgreSQL to AlloyDB using DMS. They need to set up logical replication on the source. Which THREE components are required for PostgreSQL logical replication?

Accepted Answer

pglogical extension. For PostgreSQL logical replication, the source database must have the pglogical extension installed (option B), which provides the logical replication functionality and the replication sets/slots that DMS relies on to capture changes. A publication must be created on the source database (option C) to define the set of tables whose changes are published for replication. A subscription on the destination database (option E) is required to consume the published changes and apply them, completing the logical replication topology. Option A (DMS migration job) is the overall migration mechanism, not a PostgreSQL logical replication component, and option D (replication slot) is a lower-level physical/logical streaming artifact that is created and managed as part of the pglogical/publication setup rather than being a separately required configuration component in this scenario.

Answer

DMS migration job

Answer

Replication slot

Question 6

A company is migrating from an on-premises Teradata data warehouse to BigQuery using the Schema Conversion Tool (SCTS). Which of the following is correctly handled by SCTS?

Accepted Answer

Converts Teradata BTEQ scripts to BigQuery SQL syntax.. The Schema Conversion Tool (SCTS) for Teradata to BigQuery converts Teradata BTEQ scripts into BigQuery SQL syntax as part of its schema and script conversion capabilities. BTEQ (Basic Teradata Query) is Teradata's scripting language, and SCTS translates these scripts so they can run against BigQuery. This is a core function of the tool for migrating Teradata workloads.

Answer

Converts stored procedures from Teradata PL/SQL to BigQuery SQL.

Answer

Automatically re-partitions tables based on BigQuery best practices.

Answer

Migrates actual data rows from Teradata to BigQuery.

Question 7

A team is planning a one-time migration of a 500 GB MySQL database to Cloud SQL using Database Migration Service. They want to minimize the impact on the source database. Which mysqldump flags should they use when taking the initial snapshot?

Accepted Answer

--single-transaction and --skip-lock-tables. The correct flags are --single-transaction and --skip-lock-tables. --single-transaction ensures a consistent snapshot without locking tables by using a REPEATABLE READ transaction, while --skip-lock-tables prevents any table-level locks (including the default --lock-tables behavior for MyISAM tables). Together, they minimize impact on the source database by avoiding blocking writes. This is the recommended approach for Database Migration Service (DMS) when migrating from MySQL to Cloud SQL, as it allows the initial dump to be taken without disrupting the running application.

Answer

--master-data=2 and --single-transaction

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--lock-all-tables and --flush-logs

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--all-databases and --routines

Question 8

An organization is performing a DMS continuous migration from PostgreSQL to Cloud SQL. The migration job is in the CDC phase. During a planned maintenance window, the source database is restarted. After restart, the DMS job continues to replicate but reports a lag. What is the impact of the restart on the migration?

Accepted Answer

The migration job will resume automatically from where it stopped.. Database Migration Service (DMS) continuous migrations are designed to be resilient to source database restarts. When the PostgreSQL source restarts, the DMS replication agent reconnects and resumes CDC from the last committed log position (LSN/WAL offset) it had durably recorded, so no data is lost and no new full dump is required. The reported lag is simply the backlog of WAL changes that accumulated during the restart window and is replayed automatically.

Answer

The migration job will switch to one-time migration mode.

Answer

The migration job will fail and require a new full dump.

Answer

The migration job will continue but with increased latency until all WAL is replayed.

Question 9

A company wants to migrate a 10 TB Redshift data warehouse to BigQuery with minimal downtime. Which combination of services should they use?

Accepted Answer

Use BigQuery Data Transfer Service for Redshift for initial and incremental loads.. BigQuery Data Transfer Service can directly load data from Redshift. Schema Conversion Tool (SCTS) helps convert DDL. For minimal downtime, an initial load plus CDC or incremental loads can be used.

Answer

Use DMS with a Redshift source endpoint.

Answer

Export Redshift data to CSV and load using bq load.

Answer

Use Cloud Dataflow to stream from Redshift to BigQuery.

Question 10

A team is migrating an on-premises MySQL database to Cloud SQL using DMS with continuous CDC. The source database uses public IP. The DMS connection profile for the source requires IP allowlisting. Which IP addresses should be allowlisted?

Accepted Answer

The IP address of the DMS service in the region of the destination.. When using DMS with a source database that has a public IP and requires IP allowlisting, the DMS replication instance's public IP address must be allowlisted. The DMS service in the region of the destination creates a replication instance with a public IP if configured for public access. Therefore, the IP address of the DMS service in the region of the destination (C) is correct.

Answer

The IP address of the Cloud SQL Auth Proxy.

Answer

The public IP of the Cloud SQL instance.

Answer

The private IP range of the destination VPC.

Question 11

A team is migrating a MySQL database to Cloud SQL using a manual approach (mysqldump + import) instead of DMS. They have limited bandwidth. Which TWO considerations should they take into account when choosing between DMS and manual migration? (Choose TWO.)

Accepted Answer

DMS requires the source to have binary logging enabled for continuous migration.. Option B is correct because Database Migration Service (DMS) relies on the source MySQL server's binary log (binlog) to capture ongoing changes for continuous (minimal-downtime) replication, so binary logging must be enabled on the source for that mode to work. Option E is correct because DMS compresses data during transfer, which meaningfully reduces bandwidth consumption — an important advantage given the team's limited bandwidth. Option A is not a valid consideration because mysqldump output can be piped and resumed/retried in practice, and resumability is not a defining limitation that distinguishes the two approaches here. Option C is false because DMS does support MySQL 8.0 as a source. Option D is false because manual migration is not always faster; DMS is often faster and more efficient, especially over constrained links.

Answer

Manual migration does not support resumable uploads.

Answer

DMS does not support MySQL 8.0 as a source.

Answer

Manual migration is always faster than DMS.

Question 12

A company plans to migrate a MySQL database to Cloud SQL with minimal downtime. They use Database Migration Service with continuous CDC. After starting the migration, the initial full dump completes, and CDC replication begins. The application team needs to cut over during a maintenance window. What must the engineer do just before promoting the destination to ensure no data loss?

Accepted Answer

Quiesce writes to the source, confirm replication lag is zero, then promote the destination.. Before promoting the destination, the engineer must verify that the replication lag is zero, meaning all changes from the source have been applied to the destination. This ensures no data loss during cutover. After confirming zero lag, the source should be quiesced (writes stopped) to prevent further changes, then the destination can be promoted.

Answer

Promote the destination immediately; replication lag is automatically handled.

Answer

Take a manual snapshot of the source with mysqldump and import it to the destination.

Answer

Stop the migration job and delete the source database.

Question 13

A team is migrating a PostgreSQL database to AlloyDB using Database Migration Service. They need to perform an initial one-time full dump without continuous replication. Which migration job type should they choose?

Accepted Answer

One-time. Database Migration Service offers a 'One-time' migration job type for a single full dump without continuous replication. This is exactly what the team needs: an initial one-time full dump with no ongoing change data capture.

Answer

Bulk

Answer

Continuous

Answer

Snapshot

Question 14

A company is migrating a Teradata data warehouse to BigQuery. They need to convert Teradata DDL and BTEQ scripts to BigQuery-compatible SQL. Which TWO services or tools should they use? (Choose 2 correct answers.)

Accepted Answer

Schema Conversion Tool (SCTS). Option A, Schema Conversion Tool (SCTS), is correct because Google's BigQuery Schema Conversion Tool is specifically designed to translate Teradata DDL and BTEQ scripts into BigQuery-compatible SQL, handling schema and SQL dialect conversion. Option E, BigQuery Data Transfer Service, is correct because it includes a Teradata migration connector that automates the transfer of data and can assist with the overall Teradata-to-BigQuery migration workflow, including script conversion support. Option B, Dataflow, is not correct because it is a stream and batch data processing service, not a DDL/BTEQ conversion tool. Option C, Cloud Dataproc, is not correct because it is a managed Hadoop/Spark service used for data processing, not Teradata SQL translation. Option D, BigQuery Migration Assessment, is not correct because it only assesses and plans migrations by analyzing metadata and usage, but does not perform the actual DDL and BTEQ script conversion.

Answer

Dataflow

Answer

Cloud Dataproc

Answer

BigQuery Migration Assessment

Question 15

An engineer is using Database Migration Service to migrate a MySQL database to Cloud SQL. They need to set up a source connection profile. Which TWO methods can the engineer use to allow DMS to connect to the source database? (Choose 2 correct answers.)

Accepted Answer

VPC peering for private IP. Option A (VPC peering for private IP) is correct because Database Migration Service can reach a source MySQL instance over its private IP by establishing VPC peering between the DMS-managed network and the source's VPC, which is a supported connectivity method for source connection profiles. Option C (IP allowlisting for public IP) is correct because DMS can connect to a source database over its public IP when that IP (or the DMS egress range) is added to the source's firewall allowlist, which is the standard public-IP connectivity option. Option B (No public endpoint) is not a connectivity method at all; it merely describes a source that lacks a public IP and does not by itself enable DMS connectivity. Option D (Cloud SQL Auth Proxy) is a client-side connector for securely reaching Cloud SQL instances and is not used to connect DMS to an external source database. Option E (Cloud VPN) is a networking construct that could carry traffic, but it is not one of the two DMS source connection-profile methods for reaching a MySQL source in this scenario.

Answer

No public endpoint

Answer

Cloud SQL Auth Proxy

Answer

Cloud VPN