DBS-C01 pg_dump Practice Question
A company is migrating a 50 GB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL. The network bandwidth between on-premises and AWS is 50 Mbps. The migration must complete within 24 hours. What is the most efficient way to transfer the initial data?
⚠ Common exam trap
The trap is that candidates overestimate the impact of network overhead and assume Snowball is required for any large data transfer. In reality, for a 50 GB database over a 50 Mbps link, direct network transfer is faster and simpler than physical shipping.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use pg_dump to export the database and upload to S3 via the internet, then restore into RDS.
The most efficient method is to use pg_dump to export the database, upload the dump file to Amazon S3 via the internet (or using AWS CLI with multipart upload), and then restore it into Amazon RDS for PostgreSQL. Given the database size of 50 GB and a 50 Mbps link, the theoretical transfer time is about 2.3 hours, and even with realistic overhead and retransmissions, it can complete well within the 24-hour window. This approach avoids the shipping delay and logistical overhead of AWS Snowball, which would take several days to arrive and process.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use AWS Snowball to physically transfer the database backup to AWS, then load into RDS.
Why it's wrong here
Incorrect because Snowball involves physical shipping (1–2 days) and additional steps, making it slower than direct network transfer for a 50 GB database.
- ✗
Use AWS DMS to perform a full load directly over the internet.
Why it's wrong here
Performing a full load with AWS DMS directly over the internet is inefficient for a 50 GB database due to potential network latency and throughput variability inherent in public internet connections. Although the raw bandwidth might suggest completion within 24 hours, the "most efficient" method prioritises reliability and performance. This option is tempting because AWS DMS is excellent for heterogeneous database migrations and continuous data replication (CDC), making it ideal for scenarios requiring minimal downtime or ongoing synchronisation after an initial load, often utilising more stable network paths.
- ✗
Set up a VPN connection and use AWS DMS with ongoing replication.
Why it's wrong here
Incorrect because setting up a VPN and using ongoing replication adds unnecessary complexity and overhead for just the initial data transfer; it is not the most efficient method.
- ✓
Use pg_dump to export the database and upload to S3 via the internet, then restore into RDS.
Why this is correct
Correct because pg_dump to S3 via the internet leverages the available bandwidth efficiently, and the transfer can complete in a few hours, well within the 24-hour deadline.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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