Multi Regions - datastaxdevs/awesome-astra GitHub Wiki

🏠 Back to home | Written by Cedrick Lunven, Last Update 2/10/2021

Astra Reference Documentation on this topic

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A - Overview

AstraDB allows you to replicate data across multiple regions to maintain data availability for multi-region application architectures. Configuring multiple regions can also satisfy data locality requirements with the added value of cost savings.

🔄 Eventual Consistency

Apache Cassandra® and DataStax Astra DB follow the eventual consistency model. As a result, data written to one datacenter/region may not be immediately accessible in other datacenters/regions in the same database cluster. The time span is normally within a few minutes to fully replicate the data. However, it could take longer, and possibly span one or more days. There are several contributing factors to the latter scenario, such as the workload volume, the number of regions, the process that runs data repair operations, and network resources.

⚖️ Data sovereignty

Astra DB serverless replicates all data in the database to all of a database’s regions. By contrast, multiple keyspaces in Apache Cassandra® and DataStax Enterprise (DSE) allow a database to replicate some tables to a subset of regions. To achieve the same behavior as Cassandra or DSE, create a separate AstraDB instance that adheres to the necessary region restrictions. The database client will need to add a separate connection for the additional database and send queries to the appropriate connection depending on the table being queried.

⚠️ Limitations

  • Lightweight transactions work for only a single-region datacenter.
  • If you original region is disconnected, schema changes are suspended and repairs do not run. If any regions are disconnected, the writes to those regions will not be forwarded.
  • While adding a new region, you cannot drop a table or keyspace and you cannot truncate a table.
  • If any region is not online, you cannot truncate a table.

B - Prerequisites

  • You should have an Astra account

  • You should have enter a CREDIT CARD in the system OR/AND get MORE THAN 25$ in Astra Credits.

C - Create a new Region

✅ Step 1: Click the Add Region Button

  • Select the database to show the Dashboard, select Add Region.

✅ Step 2: Select your region

  • Select your desired region from the dropdown menu of available.
  • You can review your selected region and its cost below the dropdown menu. You can add only a single region at one time.

✅ Step 3: Validate your region

  • Select Add Region to add the region to your database.

  • The database switch in maintenance status. Do not worry the existing regions remain active and available for operations there is no downtime.

After you add the new region, your new region will show up in the list of regions on your database Dashboard.

Finally after the initialization you got:

D - Delete a new Region

✅ Step 1: Select Region to delete

  • From you database Dashboard, select the overflow menu for the database you want to delete, Select Delete. You can notice that you CANNOT delete the original main region, the delete is not available in the menu

✅ Step 2: Validate your action

  • Removing a region is not reversible. Proceed with caution. A pop-up will ask you to validate this operation by entering the delete word.
  • The database will switch in maintenance mode. After a few seconds you will see the status of the deleted regions change from Active to Offline
  • Finally the region will not be visible on screen

E - Extra Resources

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