Chore: [AEA-6055] - new index for post dated (#2910)

## Summary

- 🤖 Operational or Infrastructure Change

### Details

[Fix: AEA-6055 - debugging issues with post-dated
updates](#2814)
passed on a PR branch becasue we create a new table there but
[failed](https://github.com/NHSDigital/eps-prescription-status-update-api/actions/runs/23487029492)
on merge to main:

> This AWS::dynamodb::Table resource is in a UPDATE_FAILED state.
Resource handler returned message: "Cannot update GSI's properties other
than Provisioned Throughput and Contributor Insights Specification. You
can create a new GSI with a different name." (RequestToken:
dfb5cd2a-c90c-1412-45a9-b4ae52322456, HandlerErrorCode: InvalidRequest)

So this PR creates a new secondary index to be used temporarily until we
can disable post-dated updates functionality. This is why the original
index is left in place.

Author: tstephen-nhs

SAMtemplates/tables/main.yaml

@@ -184,8 +184,6 @@ Resources:
               - TerminalStatus
               - LastModified
               - Status
-                # TODO: Remove this when we deprecate post dated prescriptions.
-              - PostDatedLastModifiedSetAt
             ProjectionType: INCLUDE
           ProvisionedThroughput: !If
             - EnableDynamoDBAutoScalingCondition
@@ -222,6 +220,27 @@ Resources:
             - ReadCapacityUnits: 1
               WriteCapacityUnits: !Ref MinWritePrescriptionStatusUpdatesCapacity
             - !Ref "AWS::NoValue"
+        - IndexName: PharmacyODSCodePrescriptionIDIndexIncPostDated
+          KeySchema:
+            - AttributeName: PharmacyODSCode
+              KeyType: HASH
+            - AttributeName: PrescriptionID
+              KeyType: RANGE
+          Projection:
+            NonKeyAttributes:
+              - PatientNHSNumber
+              - LineItemID
+              - TerminalStatus
+              - LastModified
+              - Status
+              # TODO: Remove this when we deprecate post dated prescriptions.
+              - PostDatedLastModifiedSetAt
+            ProjectionType: INCLUDE
+          ProvisionedThroughput: !If
+            - EnableDynamoDBAutoScalingCondition
+            - ReadCapacityUnits: 1
+              WriteCapacityUnits: !Ref MinWritePrescriptionStatusUpdatesCapacity
+            - !Ref "AWS::NoValue"
       Tags:
         - Key: "EPS-Tablename"
           Value: "PrescriptionStatusUpdates"
@@ -337,6 +356,56 @@ Resources:
         PredefinedMetricSpecification:
           PredefinedMetricType: DynamoDBReadCapacityUtilization
 
+  PharmacyIndexIncPostDatedScalingWriteTarget:
+    Type: AWS::ApplicationAutoScaling::ScalableTarget
+    Condition: EnableDynamoDBAutoScalingCondition
+    Properties:
+      MinCapacity: !Ref MinWritePrescriptionStatusUpdatesCapacity
+      MaxCapacity: !Ref MaxWritePrescriptionStatusUpdatesCapacity
+      ResourceId: !Sub table/${PrescriptionStatusUpdatesTable}/index/PharmacyODSCodePrescriptionIDIndexIncPostDated
+      RoleARN: !GetAtt DynamoDbScalingRole.Arn
+      ScalableDimension: "dynamodb:index:WriteCapacityUnits"
+      ServiceNamespace: dynamodb
+
+  PharmacyIndexIncPostDatedScalingWritePolicy:
+    Type: AWS::ApplicationAutoScaling::ScalingPolicy
+    Condition: EnableDynamoDBAutoScalingCondition
+    Properties:
+      PolicyName: PharmacyIndexIncPostDatedWriteScalingPolicy
+      PolicyType: TargetTrackingScaling
+      ScalingTargetId: !Ref PharmacyIndexIncPostDatedScalingWriteTarget
+      TargetTrackingScalingPolicyConfiguration:
+        TargetValue: 50
+        ScaleInCooldown: 600
+        ScaleOutCooldown: 0
+        PredefinedMetricSpecification:
+          PredefinedMetricType: DynamoDBWriteCapacityUtilization
+
+  PharmacyIndexIncPostDatedScalingReadTarget:
+    Type: AWS::ApplicationAutoScaling::ScalableTarget
+    Condition: EnableDynamoDBAutoScalingCondition
+    Properties:
+      MaxCapacity: 100
+      MinCapacity: 1
+      ResourceId: !Sub table/${PrescriptionStatusUpdatesTable}/index/PharmacyODSCodePrescriptionIDIndexIncPostDated
+      RoleARN: !GetAtt DynamoDbScalingRole.Arn
+      ScalableDimension: "dynamodb:index:ReadCapacityUnits"
+      ServiceNamespace: dynamodb
+
+  PharmacyIndexIncPostDatedScalingReadPolicy:
+    Type: AWS::ApplicationAutoScaling::ScalingPolicy
+    Condition: EnableDynamoDBAutoScalingCondition
+    Properties:
+      PolicyName: PharmacyIndexIncPostDatedReadScalingPolicy
+      PolicyType: TargetTrackingScaling
+      ScalingTargetId: !Ref PharmacyIndexIncPostDatedScalingReadTarget
+      TargetTrackingScalingPolicyConfiguration:
+        TargetValue: 70
+        ScaleInCooldown: 600
+        ScaleOutCooldown: 10
+        PredefinedMetricSpecification:
+          PredefinedMetricType: DynamoDBReadCapacityUtilization
+
   NHSNumberIndexScalingWriteTarget:
     Type: AWS::ApplicationAutoScaling::ScalableTarget
     Condition: EnableDynamoDBAutoScalingCondition

packages/gsul/src/dynamoDBclient.ts

@@ -50,7 +50,8 @@ export async function getItemsUpdatesForPrescription(
 export function createQueryCommandInput(odsCode: string, prescriptionID: string): QueryCommandInput {
   return {
     TableName: tableName,
-    IndexName: "PharmacyODSCodePrescriptionIDIndex",
+    // TODO: revert to PharmacyODSCodePrescriptionIDIndex once post-dated no longer required
+    IndexName: "PharmacyODSCodePrescriptionIDIndexIncPostDated",
     KeyConditionExpression: "PrescriptionID = :inputPrescriptionID AND PharmacyODSCode = :inputPharmacyODSCode",
     ExpressionAttributeValues: {
       ":inputPharmacyODSCode": odsCode.toUpperCase(),

packages/gsul/tests/testRunDynamoDBQueries.test.ts

@@ -48,7 +48,7 @@ describe("testing dynamoDBClient", () => {
 
     const expected = {
       TableName: undefined,
-      IndexName: "PharmacyODSCodePrescriptionIDIndex",
+      IndexName: "PharmacyODSCodePrescriptionIDIndexIncPostDated",
       KeyConditionExpression: "PrescriptionID = :inputPrescriptionID AND PharmacyODSCode = :inputPharmacyODSCode",
       ExpressionAttributeValues: {
         ":inputPharmacyODSCode": "ODSCODE",