What is cross region replication in DynamoDB?
Amazon DynamoDB now supports cross-region replication, a new feature that automatically replicates DynamoDB tables across AWS regions. You can use cross-region replication to build globally distributed applications with lower-latency data access, better traffic management, easier disaster recovery, and easier data migration.
Which AWS regions are supported for cross-region replication?
Cross-region replication and DynamoDB Streams are available in all AWS regions where DynamoDB is available. DynamoDB Triggers is available in regions where AWS Lambda is available.
How do I implement a lambda replication solution in DynamoDB?
In short, you can implement your custom solution by enabling DynamoDB Streams and connect a Lambda function to a stream which gets the database changes and reflects them in the other region. Based on your operational needs, you may implement a unidirectional or bidirectional replication solution.
What happens to my DynamoDB replica if I disable an AWS region?
If you disable an AWS Region, DynamoDB will remove this replica from the replication group, 20 hours after detecting the AWS Region as inaccessible. The replica will not be deleted and replication will stop from and to this region.
Does DynamoDB replication across availability zones?
AWS DynamoDB stores data on Solid State Drives (SSDs) and replicates it synchronously across multiple AWS Availability Zones in an AWS Region to provide built-in high availability and data durability.
Are DynamoDB tables region specific?
You can simply select the Regions where you need your data replicated, and DynamoDB handles the rest. Applications access global tables via the existing DynamoDB APIs and endpoints.
Is DynamoDB multi region by default?
By default AWS DynamoDB is a multi-AZ enabled service which means that your data is by default replicated across 3 data centers (minimum of 2 AZs) but for cross-region, you need to enable DynamoDB global tables (DynamoDB Streams).
How does replication work in DynamoDB?
DynamoDB Global Tables allows deploying a multi-region, multi-master DynamoDB replication solution. It is a fully-managed solution, where users need not write any custom code to make changes to data. DynamoDB automatically updates the data before replicating it across different regions.
How does DynamoDB global tables work?
In a global table, a newly written item is usually propagated to all replica tables within seconds. With a global table, each replica table stores the same set of data items. DynamoDB does not support partial replication of only some of the items. An application can read and write data to any replica table.
Does DynamoDB support sharding?
Partitions, keys, and write sharding At creation, DynamoDB evenly distributes the table's capacity across the underlying partitions.
Is DynamoDB automatically replicated across multiple AZS?
All of your data is stored on solid-state disks (SSDs) and is automatically replicated across multiple Availability Zones in an Amazon Region, providing built-in high availability and data durability.
Is DynamoDB faster than Aurora?
It is approx five times faster than standard MySQL databases and three times faster than standard PostgreSQL databases....Difference between Amazon Aurora and Amazon DynamoDB :S.No.Amazon AuroraAmazon DynamoDB2.It is MySQL and PostgreSQL compatible cloud service by Amazon.It is hosted, scalable database service by Amazon with data stored in Amazon cloud.9 more rows•Jul 29, 2020
Is DynamoDB eventually consistent?
DynamoDB uses eventually consistent reads, unless you specify otherwise. Read operations (such as GetItem , Query , and Scan ) provide a ConsistentRead parameter. If you set this parameter to true, DynamoDB uses strongly consistent reads during the operation.
What is the difference between DynamoDB and MongoDB?
Both these databases support multi-document transactions, but with key differences: MongoDB supports read and writes to the same documents and fields in a single database transaction. DynamoDB lacks support for multiple operations within a single transaction.
What type of database is DynamoDB?
key-value NoSQL databaseAmazon DynamoDB is a fully managed, serverless, key-value NoSQL database designed to run high-performance applications at any scale. DynamoDB offers built-in security, continuous backups, automated multi-Region replication, in-memory caching, and data export tools.
How do I create a global table in DynamoDB?
Creating a global table (console)In the navigation pane on the left side of the console, choose Tables.Choose Create Table. ... Choose the Global Tables tab, and then choose Create a version 2017.11. ... From the Available replication Regions dropdown, choose US West (Oregon). ... Choose Create Replica.More items...•
DynamoDB stream
I’ll use a sample ‘Employee’ table to demonstrate. The table has a unique ID and a Name column. I’ve create the table in the us-west-2 region.
Destination table
Next, I created a destination table in the us-east-1 region. Make sure the primary key name and type matches the source table.
Lambda function
Next we’ll create a lambda function to process events from the DB stream.
IAM Role
Next we’ll create an IAM role with permissions to access the DynamoDB stream, the destination table and to invoke the lambda function we created above. We’ll also add the ARN’s of the stream, source table, destination table and the lambda function to the role so the permissions are limited to just these resources.
What is DynamoDB AWS?
DynamoDB is a fully managed NoSQL database by AWS. It has a scheme-less architecture and supports both Document Data Model and Key-Value Data Model. To achieve high uptime and durability, DynamoDB supports automatic and synchronous data replication across three facilities ( Availability Zones) in a region. This is to protect your data against individual node or even facility level failures. Although this is a great built-in feature to mitigate zone based failures, this will not work in case of a regional failure. There is no built-in protection for regional failures, at least for now. However, in mission-critical systems, regional failures should be handled in order to have a robust system which also should be highly available, fault-tolerant and resilient. Cross-region replication can be a good solution to handle regional failures when using DynamoDB.
Does Amazon S3 support cross region replication?
Amazon S3 supports built-in bidirectional cross-region replication for buckets so that you can be sure that your files will be replicated and synchronized across the regions. This ensures that even if one of the regions is unavailable, you can read your data on the other region. On the other hand, DynamoDB does not support built-in cross-region replication. An external solution is required to replicate the DynamoDB tables across the regions.
Can two requests be routed to different regions?
In this approach, consecutive two requests of a client can be routed to different regions.This means that a single database record can be modified from both two regions. In this case, replication delays should be close to zero as much as possible, and the replication Lambdas should ensure that inconsistencies are resolved before reflecting the changes.
3. Upload the Lambda Function
Create a role in IAM and assign it to the lambda function. Make sure to add policies to the role that allow read/write access to DynamoDB.
4. Create Event Source Mapping in AWS Lambda
This event source mapping associates the DynamoDB stream with your lambda function. After you create this event source mapping, AWS lambda starts polling the stream.
AWS DynamoDB in Short
Need For Replication
Replicating AWS DynamoDB Across The Regions
Unidirectional Replication Architecture
Bidirectional Replication Architecture
Resolving Conflicts
- Replication is the process of copying data from one place to another. The objectives of the replication are; 1. To store data redundant for backup purposes 2. To have robust and fault tolerant system 3. To minimize MTTR (Mean-Time-To-Repair) time 4. To maximize availability 5. Always up and running systems 6. To handle regional or service layer failures On the other hand…
Replication Monitoring
- Amazon S3supports built-in bidirectional cross-region replication for buckets so that you can be sure that your files will be replicated and synchronized across the regions. This ensures that even if one of the regions is unavailable, you can read your data on the other region. On the other hand, DynamoDB does not support built-in cross-region repl...
Data Booting & Verification
- Let’s assume that we are using Oregon and Ohio regions for our application as the primary and backup region, respectively. So, the applications are running on instances in Oregon, and they are using DynamoDB in Oregon as well. In this scenario, we enable unidirectional replication, from Oregon to Ohio as seen in the figure. We can think of this as a backup mechanism so that in a c…
Handling Delays
- In a distributed world, we may need to run our applications within two distinct regions simultaneously. It helps us to distribute the traffic evenly or provide low latency for the customers all over the world. As we will have two distinct databases in different regions, we need to synchronize the data and try to make sure that the applications running in distinct regions are re…
Failover
- We should resolve the conflicts that may occur before reflecting the changes. Since entire replication process is running asynchronously, our distributed applications across the regions may change the very same entity at the same time. This introduces race conditions between applications that may lead to inconsistencies unless we can decide on a winner. Thus, to preven…