miztiik/dynamodb-global-tables

Amazon DynamoDB global tables provide a fully managed solution for deploying a multi-region, multi-master database.

AWS DynamoDB Global Tables: Multi Region, Multi Master Database

As a learning exercise, lets use the AWS Documentation and find out how to create Global Multi Master, Multi Region database with DynamoDB and verify latency.

A global table is a collection of one or more replica tables, all owned by a single AWS account. A replica table (or replica, for short) is a single DynamoDB table that functions as a part of a global table. Each replica stores the same set of data items. Any given global table can only have one replica table per region.

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Setup The Tables

The following is a conceptual overview of how a global table is created.

1. Create an ordinary DynamoDB table, with DynamoDB Streams enabled, in an AWS region.

   • Region 1 - Singapore
   • Region 2 - Virginia
   • Region 3 - Ireland

2. Repeat step 1 for every other AWS region where you want to replicate your data.

3. Define a DynamoDB global table, based upon the tables that you have created.

4. Create a new table (Music) in Singapore, with DynamoDB Streams enabled (NEW_AND_OLD_IMAGES):

   aws dynamodb create-table \
       --table-name Music \
       --attribute-definitions \
           AttributeName=Artist,AttributeType=S \
           AttributeName=SongTitle,AttributeType=S \
       --key-schema \
           AttributeName=Artist,KeyType=HASH \
           AttributeName=SongTitle,KeyType=RANGE \
       --provisioned-throughput \
           ReadCapacityUnits=1,WriteCapacityUnits=1 \
       --stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES \
       --region ap-southeast-1

5. Create an identical Music table in US East (N. Virginia):

   aws dynamodb create-table \
       --table-name Music \
       --attribute-definitions \
           AttributeName=Artist,AttributeType=S \
           AttributeName=SongTitle,AttributeType=S \
       --key-schema \
           AttributeName=Artist,KeyType=HASH \
           AttributeName=SongTitle,KeyType=RANGE \
       --provisioned-throughput \
           ReadCapacityUnits=1,WriteCapacityUnits=1 \
       --stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES \
       --region us-east-1

6. Create a global table (Music) consisting of replica tables in the ap-southeast-1 and us-east-1 regions.

   aws dynamodb create-global-table \
       --global-table-name Music \
       --replication-group RegionName=ap-southeast-1 RegionName=us-east-1 \
       --region ap-southeast-1

7. Create another table in EU (Ireland), with the same settings as those you created in Step 1 and Step 2:

   aws dynamodb create-table \
       --table-name Music \
       --attribute-definitions \
           AttributeName=Artist,AttributeType=S \
           AttributeName=SongTitle,AttributeType=S \
       --key-schema \
           AttributeName=Artist,KeyType=HASH \
           AttributeName=SongTitle,KeyType=RANGE \
       --provisioned-throughput \
           ReadCapacityUnits=1,WriteCapacityUnits=1 \
       --stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGES \
       --region eu-west-1

   After you have done this, add this new table to the Music global table:

   aws dynamodb update-global-table \
       --global-table-name Music \
       --replica-updates 'Create={RegionName=eu-west-1}' \
       --region ap-southeast-1

Verify Global Replication

1. To verify that replication is working, add a new item to the Music table in Singapore:

   aws dynamodb put-item \
       --table-name Music \
       --item '{"Artist": {"S":"item_1"},"SongTitle": {"S":"Song Value 1"}}' \
       --region ap-southeast-1

2. Wait for a few seconds, and then check to see if the item has been successfully replicated to US East (N. Virginia) and EU (Ireland):

   aws dynamodb get-item \
       --table-name Music \
       --key '{"Artist": {"S":"item_1"},"SongTitle": {"S":"Song Value 1"}}' \
       --region us-east-1

   aws dynamodb get-item \
       --table-name Music \
       --key '{"Artist": {"S":"item_1"},"SongTitle": {"S":"Song Value 1"}}' \
       --region eu-west-1

Timing Your Insert/Read Queries

Lets do some crude inserts and time their replication

for i in {2..10}
 do
  val=${RANDOM}
  t=2
  # Insert Items
  echo -e "\n\n-=-=- Inserting Item:item_${i} and Retrieving after ${t} Seconds -=-=-"
  aws dynamodb put-item --table-name Music --item '{"Artist": {"S":"item_'${i}'"},"SongTitle": {"S":"Song Value '${val}'"}}' --region ap-southeast-1
  sleep ${t}
  # Read Items
  time aws dynamodb get-item --table-name Music --key '{"Artist": {"S":"item_'${i}'"},"SongTitle": {"S":"Song Value '${val}'"}}' --region eu-west-1
 done

Contact Us

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References

1. AWS Docs