Using global databases with Amazon Neptune - Amazon Neptune
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Using global databases with Amazon Neptune

An Amazon Neptune global database spans multiple Amazon Web Services Regions, enabling low-latency global reads and providing fast recovery in the rare case where an outage affects an entire Amazon Web Services Region.

A Neptune global database consists of a primary DB cluster in one region, and up to five secondary DB clusters in different regions.

Writes can only occur in the primary region. Secondary regions only support reads. Each secondary region can have up to 16 reader instances.

Overview of global databases in Amazon Neptune

Using a Neptune global database, you can run your globally distributed applications on a single database that spans multiple Amazon Web Services Regions.

A Neptune global database consists of one DB cluster in a primary Amazon Web Services Region where data is written, and up to five read-only DB clusters in secondary Amazon Web Services Regions. When you perform a write operation on the primary DB cluster, Neptune replicates the written data to all the secondary DB clusters using dedicated infrastructure, with latency typically under a second.

The following diagram shows an example global database that spans two Amazon Web Services Regions:

A Neptune global database has one primary DB cluster and one or more
        secondary DB clusters.

You can scale each secondary cluster independently to handle read-only workloads by adding one or more read-replica instances.

To perform a write operations, you must connect to the DB cluster endpoint of the primary DB cluster. Only the primary cluster can perform write operations. Then, as shown in the diagram above, replication is performed by the cluster storage volume, not the database engine.

Neptune global databases are designed for applications with a worldwide footprint. The read-only secondary DB clusters support read operations closer to application users.

A Neptune global database supports two different approaches to failover:

  • To recover from an outage in the primary region, use the manual unplanned detach-and-promote process, where you detach one the secondary clusters, turning it into a standalone cluster, and then promote it to be the new primary cluster.

  • For planned operational procedures such as maintenance, use managed planned failover, where you relocate the primary cluster to one of its secondary regions with no data loss.

Advantages of using global databases in Amazon Neptune

Using a global database, has the following advantages:

  • Global reads with local latency   —   If you have offices around the world, a global database lets your offices in secondary regions access data in their own region with local latency.

  • Scalable secondary Neptune DB clusters   —   You can scale secondary clusters by adding read-replica DB instances. Because secondary clusters are read-only, they can each support up to 16 read-replicas rather than the usual limit of 15.

  • Fast replication to secondary DB clusters   —   Replication from primary to secondary DB clusters is fast, with latency typically under a second, with little performance impact on the primary DB cluster. Because the replication is performed at the storage level, DB instance resources are fully available for application read and write workloads.

  • Recovery from region-wide outages   —   The secondary DB clusters allow you to move the primary cluster to a new region more quickly, with lower RTO and less data loss (lower RPO) than traditional replication solutions.

Limitations of global databases in Amazon Neptune

The following limitations currently apply to global databases:

  • Neptune global databases are only available in the following Amazon Web Services Regions:

    • US East (N. Virginia):   us-east-1

    • US East (Ohio):   us-east-2

    • US West (N. California):   us-west-1

    • US West (Oregon):   us-west-2

    • Europe (Ireland):   eu-west-1

    • Europe (London):   eu-west-2

    • Asia Pacific (Tokyo):   ap-northeast-1

  • Neptune global databases don't support auto-scaling for secondary DB clusters.

  • You can't apply a custom parameter group to the global database cluster while you're performing a major version upgrade of that global database. Instead, create your custom parameter groups in each region of the global cluster and then apply them manually to the regional clusters after the upgrade.

  • You can't stop or start the DB clusters in a global database individually.

  • Read-replica intances in a secondary DB cluster can restart under certain circumstances. If the primary cluster's writer instance restarts or fails over, all the instances in secondary regions also restart. The secondary cluster is then unavailable until all its instances are back in sync with the primary DB cluster's writer instance.