Resource ARN mismatch during Point-in-Time Recovery (PITR) restore

Question

Amazon DynamoDB Point-in-Time Recovery (PITR) allows for the restoration of table data to a specific timestamp within a 35-day window. However, the restoration process creates a completely new table with a unique Amazon Resource Name (ARN) rather than restoring data into the existing table structure.

In environments where application configurations, IAM policies, or CloudFormation stacks are tightly coupled to a specific table ARN, this behavior introduces a synchronization gap. Since the original table remains intact and the restored table is a separate entity, the application must be manually or programmatically updated to point to the new resource.

How can the transition to a new restored table ARN be managed without causing application downtime?
  Is there a documented method to maintain consistent IAM policy associations when the target table resource changes during a PITR event?

Zoha · Answer

Resolving the PITR Resource Gap
To manage the transition to a new restored table ARN without downtime, you must decouple your application from specific resource identifiers using environment variables or AWS Systems Manager (SSM) Parameter Store. Because DynamoDB PITR always creates a new table with a unique ARN, you cannot "overwrite" the existing resource; you must redirect the application to the new target.

Zero-Downtime Transition Strategy
The most effective way to avoid downtime is to implement a dynamic configuration lookup rather than hardcoding ARNs in your application code or IAM policies. Follow these steps:

Abstract the Resource: Store the current active table name or ARN in an SSM Parameter (e.g., /prod/app/dynamodb-table-arn).
  Restore the Table: Perform the PITR restore to a new table (e.g., Table_Restored_2026-10-04).
  Update Permissions: Apply the necessary IAM policies to the new ARN (see below).
  Atomic Switch: Update the SSM Parameter value to the new ARN. If your application caches this value, trigger a rolling restart or use a configuration refresh listener to pick up the change.
  Cleanup: Once the application is verified against the restored table, delete the corrupted or old table.

Maintaining Consistent IAM Policies
There is no native AWS feature to "transfer" an IAM policy association from a source table to a restored table because the ARN is the unique identifier. To maintain consistency, use IAM Resource Wildcards or Tags:

Prefix-based Wildcards: If your tables follow a naming convention (e.g., AppTable_), define your IAM policy resource as arn:aws:dynamodb:region:account-id:table/AppTable_*. This ensures any restored table following the prefix is automatically covered.
  Attribute-Based Access Control (ABAC): Use tags to grant access. Instead of scoping the policy to a specific ARN, scope it to any resource with the tag Environment: Production. When you restore the table, ensure the restoration process or a post-restore script applies the required tags.

Verification
Before switching traffic, verify the new ARN and permissions using the AWS CLI:
# Verify the new table ARN
aws dynamodb describe-table --table-name YourRestoredTableName

# Test IAM permissions with the restored ARN
aws iam simulate-principal-policy --policy-source-arn arn:aws:iam::account-id:role/AppRole --action-names dynamodb:GetItem --resource-arns arn:aws:dynamodb:region:account-id:table/YourRestoredTableName

Diagnostic Detail Needed: Are you using a specific Infrastructure-as-Code (IaC) tool like Terraform or CloudFormation to manage these policies? If so, the recommendation shifts toward updating the stack parameters rather than manual SSM updates.

Resource ARN mismatch during Point-in-Time Recovery (PITR) restore

1 answer

0 question comments

Resolving the PITR Resource Gap

Zero-Downtime Transition Strategy

Maintaining Consistent IAM Policies

Verification

Your perspective belongs here.