Amazon Neptune Interview Q/A

1. What is Amazon Neptune?

   Amazon Neptune is a fully managed graph database service designed for highly connected datasets. It offers support for graph query languages, making it easy to build and run applications that work with complex, interconnected data. Neptune is optimized for storing vast numbers of relationships and enables applications such as recommendation engines, fraud detection, knowledge graphs, drug discovery, and network security. It takes care of provisioning, patching, backup, recovery, failure detection, and repair, with a simple monthly pricing model.

2. What popular graph query languages does Amazon Neptune support?

   Amazon Neptune supports two popular graph query languages: Apache TinkerPop Gremlin and RDF SPARQL. These languages allow users to execute powerful graph queries on Neptune databases.

3. Can I use Apache TinkerPop Gremlin and RDF/SPARQL on the same Neptune instance?

   Yes, you can use both Gremlin and SPARQL on the same Neptune instance. However, the data is separated between the two languages, meaning you cannot execute Gremlin queries on RDF data or vice versa. In production, it's recommended to choose one language (Gremlin or SPARQL) for accessing the instance.

4. How can I migrate from an existing Apache TinkerPop Gremlin application to Amazon Neptune?

   Amazon Neptune provides an Apache TinkerPop Gremlin Server that supports Websocket and REST connections. To migrate an existing TinkerPop application, you can configure it to use the endpoint provided by Amazon Neptune.

5. Do I need to change client drivers to use Amazon Neptune’s Gremlin Server?

   No, you don't need to change client drivers to use Amazon Neptune's Gremlin Server. It supports clients that are compatible with Apache TinkerPop version 3.3 using both Websocket and REST connections.

6. How can I migrate from a triple store with a SPARQL endpoint to Amazon Neptune?

   Amazon Neptune provides an HTTP REST endpoint that implements the SPARQL 1.1 Protocol. You can configure your application to point to this SPARQL endpoint once you provision a Neptune instance.

7. Do I need to change client drivers to use Amazon Neptune’s SPARQL Endpoint?

   No, Amazon Neptune's SPARQL endpoint works with any client that supports the SPARQL 1.1 Protocol.

8. Is Neptune ACID (Atomicity, Consistency, Isolation, Durability) compliant?

   Yes, Amazon Neptune is ACID compliant with immediate consistency.

9. Why are Amazon RDS permissions and resources required to use Amazon Neptune?

   Amazon Neptune leverages operational technology shared with Amazon RDS for certain management features, such as instance lifecycle management, encryption at rest with Amazon KMS keys, and security group management.

10. Does Amazon Neptune have a service level agreement (SLA)?

    Yes, there is an Amazon Neptune SLA that you can refer to for details.

These questions cover various aspects of Amazon Neptune, including its capabilities, query language support, migration, pricing, performance, high availability, and security features.

1. What types of graph query workloads are optimized to work with Amazon Neptune?

   Amazon Neptune is designed to support graph applications that require high throughput and low latency graph queries. It can handle high query volumes with support for up to 15 read replicas, making it suitable for workloads like recommendation engines and fraud detection.

2. Does Amazon Neptune perform query optimization?

   Yes, Amazon Neptune employs query optimization for both SPARQL queries and Gremlin traversals, ensuring efficient query execution.

3. Is Amazon Neptune built on a relational database?

   No, Amazon Neptune is not built on a relational database. It is a purpose-built, high-performance graph database engine optimized for storing and querying graph data efficiently.

4. How much does Amazon Neptune cost?

   Pricing details for Amazon Neptune can be found on their pricing page, where you can get information on the costs associated with different instance types and features.

5. In which AWS regions are Amazon Neptune available?

   You can check the AWS pricing page for current information on the availability of Amazon Neptune in different AWS regions.

6. Does Amazon Neptune's replication affect the effective storage price?

   No, Amazon Neptune's replication is bundled into the price. You are charged based on the storage your database consumes at the database layer, not the storage consumed in Amazon Neptune’s virtualized storage layer.

7. What are IOs in Amazon Neptune and how are they calculated?

   Amazon Neptune minimizes unnecessary IO operations to reduce costs. Write IOs are only consumed when pushing transaction log records to the storage layer to make writes durable. These write IOs are counted in 4KB units, resulting in savings compared to traditional database engines.

8. What are the minimum and maximum storage limits of an Amazon Neptune database?

   The minimum storage for Amazon Neptune is 10GB. The storage can automatically grow based on your database usage, up to a maximum of 64 TB in 10GB increments without impacting performance.

9. How do I scale the compute resources associated with my Amazon Neptune DB Instance?

   You can scale the compute resources allocated to your Amazon Neptune DB Instance through the AWS Management Console by selecting the desired DB Instance and modifying its memory and CPU resources.

10. How do I enable backups for my DB Instance?

    Automated backups are always enabled on Amazon Neptune DB Instances, and they do not impact the database's performance.

These questions delve into pricing, scalability, storage, and backup-related aspects of Amazon Neptune. They also address how Neptune ensures data availability and resilience through replication and failover mechanisms. Finally, they touch upon the security features provided by Amazon Neptune.

1. Can I take DB Snapshots and keep them around as long as I want?
   Yes, you can take DB Snapshots, and there is no performance impact when creating them. You can retain these snapshots for as long as you need.

2. If my database fails, what is my recovery path?

   Amazon Neptune automatically maintains multiple copies of your data in different Availability Zones, ensuring data durability and recoverability. In the event of a database failure, it will attempt to recover the database in a healthy Availability Zone with minimal data loss. You can also use DB Snapshots for recovery.

3. What happens to my automated backups and DB Snapshots if I delete my DB Instance?

   You can create a final DB Snapshot when deleting your DB Instance. Amazon Neptune retains this final user-created DB Snapshot along with any manually created DB Snapshots after the DB Instance is deleted. However, automated backups created for point-in-time restore are not kept.

4. Can I share my snapshots with another AWS account?

   Yes, you can share your Amazon Neptune snapshots with another AWS account, allowing the recipient account to use the snapshot to restore a database.

5. Will I be billed for shared snapshots?

   There is no charge for sharing snapshots between accounts. However, you may be charged for the snapshots themselves and for any databases you restore from shared snapshots.

6. Can I automatically share snapshots?

   Amazon Neptune does not support sharing automatic DB snapshots. To share an automatic snapshot, you must manually create a copy of the snapshot and then share the copy.

7. How many accounts can I share snapshots with?

   You can share manual snapshots with up to 20 AWS account IDs. If you need to share snapshots with more than 20 accounts, you can choose to share the snapshot as public or contact AWS support to increase your quota.

8. In which regions can I share my Amazon Neptune snapshots?

   You can share your Amazon Neptune snapshots in all AWS regions where Amazon Neptune is available.

9. Can I share my Amazon Neptune snapshots across different regions?

   No, shared Amazon Neptune snapshots are only accessible by accounts in the same region as the account that shares them.

10. Can I share an encrypted Amazon Neptune snapshot?

    Yes, you can share encrypted Amazon Neptune snapshots.

11. Can I use Amazon Neptune snapshots outside of the service?

    Amazon Neptune snapshots are intended for use within the service and cannot be used outside of it.

12. How does Amazon Neptune improve my database’s fault tolerance for disk failures?

    Amazon Neptune enhances fault tolerance by automatically dividing the database volume into 10GB segments spread across multiple disks and replicating each segment six ways across three Availability Zones.

13. How does Amazon Neptune improve recovery time after a database crash?

    Unlike some other databases, Amazon Neptune does not need to replay the redo log from the last database checkpoint after a crash, significantly reducing recovery time. The buffer cache is moved out of the database process, making it available immediately at restart.

14. What kind of replicas does Neptune support?

    Amazon Neptune supports Read Replicas, which share the same underlying volume as the primary instance. They provide low-latency read access and can be promoted to primary in case of a primary DB Instance failure.

15. Can I have cross-region replicas with Amazon Neptune?

    No, Amazon Neptune does not support cross-region replicas.

16. Can I prioritize certain replicas as failover targets over others?

    Yes, you can assign a promotion priority tier to each replica, and Amazon Neptune will promote the replica with the highest priority to the primary in the event of a failover.

17. Can I modify priority tiers for instances after they have been created?

    You can modify the priority tier for an instance at any time, and it won't trigger a failover.

18. Can I prevent certain replicas from being promoted to the primary instance?

    You can assign lower priority tiers to replicas you don't want to be promoted. However, if higher-priority replicas are unavailable, Neptune may promote lower-priority replicas.

19. How can I improve upon the availability of a single Amazon Neptune database?

    You can enhance the availability of your Amazon Neptune database by adding Read Replicas. Amazon Neptune Replicas can be promoted to the primary without data loss in the event of a failure, improving fault tolerance.

20. What happens during failover and how long does it take?

    Amazon Neptune automatically handles failover. If you have a replica, failover typically takes around 30 seconds. Without a replica, Neptune will attempt to create a new instance, and the failover usually completes in under 15 minutes. Applications should be prepared to retry database requests in case of a connection loss.

These questions continue to explore backup and recovery, replication, and high availability features of Amazon Neptune, ensuring data durability, fault tolerance, and rapid recovery in case of database failures.