How Does DynamoDB Global Tables Replicate Data Across Regions?

Amazon DynamoDB global tables enable multi-Region, multi-active data replication, ensuring that write and read operations performed in one AWS Region are automatically synchronized across all designated replica regions. This continuous replication capability allows globally distributed applications to access local data with single-digit millisecond latency while maintaining high availability and disaster recovery readiness.

Fully Managed Asynchronous Replication

DynamoDB global tables rely on fully managed asynchronous replication. When an application writes, updates, or deletes an item in one replica table, DynamoDB automatically captures the mutation and propagates the changes to the replica tables in all other designated AWS Regions. Because the replication occurs asynchronously, write operations complete immediately in the local region without waiting for cross-region network round trips. This design delivers fast write performance locally while achieving eventual consistency across all global replicas.

Multi-Active Read and Write Capabilities

Unlike active-passive replication models where a single primary region accepts writes, global tables operate on a multi-active (active-active) replication model. Applications can issue read and write requests to any replica table in any configured AWS Region. Every replica table acts as a full-fledged DynamoDB table capable of serving both reads and writes. DynamoDB tracks changes across all regions and continuously reconciles the state of the data globally.

Automated Conflict Resolution

In a multi-active replication architecture, concurrent writes to the same item in different regions can result in update conflicts. DynamoDB global tables automatically resolve these conflicts using a last-writer-wins mechanism. During a write, DynamoDB records a timestamp for the item mutation. When concurrent updates occur across regions, DynamoDB evaluates the timestamps and propagates the update with the latest timestamp to all replicas. This ensures that all replica tables eventually converge to the exact same dataset.

Stream-Based Change Data Capture

Underneath the managed layer, global tables utilize DynamoDB Streams or internal change-data-capture mechanisms to track item-level modifications. Every insert, update, or deletion creates a stream record containing the old and new state of the item. Global tables leverage this ordered sequence of events to ensure that cross-region updates are applied in the correct sequence across all target regions.

Regional Secondary Index Synchronization

Replication in global tables extends beyond the primary table data. Global Secondary Indexes (GSIs) configured on a global table are automatically replicated and synchronized in every replica region. When an item update in one region modifies an indexed attribute, DynamoDB propagates the change across the global network and updates the corresponding secondary indexes in all target regions, maintaining search and query performance globally.