diff --git a/deploy/service-bus/deploy.config.js b/deploy/service-bus/deploy.config.js
index 76f17a3d79..f6dbc8bc91 100644
--- a/deploy/service-bus/deploy.config.js
+++ b/deploy/service-bus/deploy.config.js
@@ -92,7 +92,8 @@ const config = {
     {
       name: 'ps-report-staging-complete',
       defaultMessageTimeToLive: sixHours,
-      maxSizeInMegabytes: {}.hasOwnProperty.call(process.env, 'SERVICE_BUS_QUEUE_MAX_SIZE_MEGABYTES_PS_REPORT_EXPORT') ? parseInt(process.env.SERVICE_BUS_QUEUE_MAX_SIZE_MEGABYTES_PS_REPORT_EXPORT, 10) : eightyGigabytes
+      maxSizeInMegabytes: {}.hasOwnProperty.call(process.env, 'SERVICE_BUS_QUEUE_MAX_SIZE_MEGABYTES_PS_REPORT_EXPORT') ? parseInt(process.env.SERVICE_BUS_QUEUE_MAX_SIZE_MEGABYTES_PS_REPORT_EXPORT, 10) : eightyGigabytes,
+      requiresDuplicateDetection: true
     },
     {
       name: 'pupil-login',
diff --git a/tslib/src/functions-ps-report/ps-report-3b-stage-csv-file/index.ts b/tslib/src/functions-ps-report/ps-report-3b-stage-csv-file/index.ts
index e4c810eb3f..c37fc5f2fd 100644
--- a/tslib/src/functions-ps-report/ps-report-3b-stage-csv-file/index.ts
+++ b/tslib/src/functions-ps-report/ps-report-3b-stage-csv-file/index.ts
@@ -10,6 +10,7 @@ import { CsvTransformer } from './csv-transformer'
 import type { PsReportStagingStartMessage, PsReportStagingCompleteMessage } from '../common/ps-report-service-bus-messages'
 
 const functionName = 'ps-report-3b-stage-csv-file'
+let logPrefix = functionName
 const receiveQueueName = 'ps-report-export'
 const sleep = async (ms: number): Promise<void> => { return new Promise((resolve) => setTimeout(resolve, ms)) }
 let emptyPollTime: undefined | number
@@ -24,11 +25,12 @@ let psReportStagingDataService: PsReportStagingDataService
  *
 */
 const PsReportStageCsvFile: AzureFunction = async function (context: Context, incomingMessage: PsReportStagingStartMessage): Promise<void> {
-  context.log(`${functionName}: starting`)
+  logPrefix = functionName + ': ' + context.invocationId
+  context.log(`${logPrefix}: starting`)
   const start = performance.now()
 
   if (config.ServiceBus.ConnectionString === undefined) {
-    throw new Error(`${functionName}: ServiceBusConnection env var is missing`)
+    throw new Error(`${logPrefix}: ServiceBusConnection env var is missing`)
   }
 
   let busClient: sb.ServiceBusClient
@@ -43,18 +45,18 @@ const PsReportStageCsvFile: AzureFunction = async function (context: Context, in
 
   // connect to service bus...
   try {
-    context.log(`${functionName}: connecting to service bus...`)
+    context.log(`${logPrefix}: connecting to service bus...`)
     busClient = new sb.ServiceBusClient(config.ServiceBus.ConnectionString)
     receiver = busClient.createReceiver(receiveQueueName, {
       receiveMode: 'peekLock'
     })
-    context.log(`${functionName}: connected to service bus instance ${busClient.fullyQualifiedNamespace}`)
+    context.log(`${logPrefix}: connected to service bus instance ${busClient.fullyQualifiedNamespace}`)
   } catch (error) {
     let errorMessage = 'unknown error'
     if (error instanceof Error) {
       errorMessage = error.message
     }
-    context.log.error(`${functionName}: unable to connect to service bus at this time: ${errorMessage}`)
+    context.log.error(`${logPrefix}: unable to connect to service bus at this time: ${errorMessage}`)
     throw error
   }
 
@@ -69,7 +71,7 @@ const PsReportStageCsvFile: AzureFunction = async function (context: Context, in
     if (error instanceof Error) {
       errorMessage = error.message
     }
-    context.log.error(`${functionName}: unable to connect to service bus at this time: ${errorMessage}`)
+    context.log.error(`${logPrefix}: unable to connect to service bus at this time: ${errorMessage}`)
     throw error
   }
 
@@ -77,20 +79,22 @@ const PsReportStageCsvFile: AzureFunction = async function (context: Context, in
   let batchIndex = 0
 
   while (!done) {
-    context.log(`${functionName}: starting batch ${batchIndex + 1}`)
+    context.log(`${logPrefix}: starting batch ${batchIndex + 1}`)
     const messageBatch = await receiver.receiveMessages(config.PsReport.StagingFile.ReadMessagesPerBatch)
     if (RA.isNilOrEmpty(messageBatch)) {
-      context.log(`${functionName}: no messages to process`)
+      context.log(`${logPrefix}: no messages to process`)
       if (emptyPollTime === undefined) {
-        context.log(`${functionName}: Setting flag to mark the time since no messages were found.`)
+        context.log(`${logPrefix}: Setting flag to mark the time since no messages were found.`)
         emptyPollTime = getEpoch()
       }
       const nowEpoch = getEpoch()
       const timeSinceLastMessage = nowEpoch - emptyPollTime
-      context.log(`${functionName}: nowEpoch: ${nowEpoch} emptyPollTime: ${emptyPollTime} timeSinceLastMessage: ${timeSinceLastMessage} target wait time is ${config.PsReport.StagingFile.WaitTimeToTriggerStagingComplete}`)
+      context.log(`${logPrefix}: nowEpoch: ${nowEpoch} emptyPollTime: ${emptyPollTime} timeSinceLastMessage: ${timeSinceLastMessage} target wait time is ${config.PsReport.StagingFile.WaitTimeToTriggerStagingComplete}`)
       if (timeSinceLastMessage >= config.PsReport.StagingFile.WaitTimeToTriggerStagingComplete) {
-        context.log(`${functionName}: exiting as no new messages in ${config.PsReport.StagingFile.WaitTimeToTriggerStagingComplete} seconds.`)
+        context.log(`${logPrefix}: exiting (and sending output binding message) as no new messages in ${config.PsReport.StagingFile.WaitTimeToTriggerStagingComplete} seconds.`)
         done = true
+
+        // This message should be delivered once - duplicatePrevention is on the sb queue.
         const completeMessage: PsReportStagingCompleteMessage = {
           filename: incomingMessage.filename,
           jobUuid: incomingMessage.jobUuid
@@ -99,7 +103,7 @@ const PsReportStageCsvFile: AzureFunction = async function (context: Context, in
         await disconnect()
         return finish(start, context)
       } else {
-        context.log(`${functionName}: waiting for messages...`)
+        // context.log(`${logPrefix}: waiting for messages...`)
         await sleep(config.PsReport.StagingFile.PollInterval) // wait n milliseconds before polling again. Default is 10.
       }
     } else {
@@ -107,7 +111,7 @@ const PsReportStageCsvFile: AzureFunction = async function (context: Context, in
       // so, 1st reset the timer, as it may have been set previously
       emptyPollTime = undefined
       // and process the messages
-      context.log(`${functionName}: received batch of ${messageBatch.length} messages`)
+      context.log(`${logPrefix}: received batch of ${messageBatch.length} messages`)
       await process(context, messageBatch, receiver)
     }
 
@@ -122,7 +126,7 @@ function finish (start: number, context: Context): void {
   const end = performance.now()
   const durationInMilliseconds = end - start
   const timeStamp = new Date().toISOString()
-  context.log(`${functionName}: ${timeStamp} run complete: ${durationInMilliseconds} ms`)
+  context.log(`${logPrefix}: ${timeStamp} run complete: ${durationInMilliseconds} ms`)
 }
 
 async function completeMessages (messageBatch: sb.ServiceBusReceivedMessage[], receiver: sb.ServiceBusReceiver, context: Context): Promise<void> {
@@ -130,7 +134,7 @@ async function completeMessages (messageBatch: sb.ServiceBusReceivedMessage[], r
   // if any completes fail, just abandon.
   // the sql updates are idempotent and as such replaying a message
   // will not have an adverse effect.
-  context.log(`${functionName}: batch processed successfully, completing all messages in batch`)
+  context.log(`${logPrefix}: batch processed successfully, completing all messages in batch`)
   for (let index = 0; index < messageBatch.length; index++) {
     const msg = messageBatch[index]
     try {
@@ -143,7 +147,7 @@ async function completeMessages (messageBatch: sb.ServiceBusReceivedMessage[], r
         if (error instanceof Error) {
           errorMessage = error.message
         }
-        context.log.error(`${functionName}: unable to abandon message:${errorMessage}`)
+        context.log.error(`${logPrefix}: unable to abandon message:${errorMessage}`)
         // do nothing.
         // the lock will expire and message reprocessed at a later time
       }
@@ -161,7 +165,7 @@ async function abandonMessages (messageBatch: sb.ServiceBusReceivedMessage[], re
       if (error instanceof Error) {
         errorMessage = error.message
       }
-      context.log.error(`${functionName}: unable to abandon message:${errorMessage}`)
+      context.log.error(`${logPrefix}: unable to abandon message:${errorMessage}`)
     }
   }
 }
diff --git a/tslib/src/functions-ps-report/ps-report-3b-stage-csv-file/ps-report-staging.data.service.ts b/tslib/src/functions-ps-report/ps-report-3b-stage-csv-file/ps-report-staging.data.service.ts
index 0e940a5f2d..7087e947fe 100644
--- a/tslib/src/functions-ps-report/ps-report-3b-stage-csv-file/ps-report-staging.data.service.ts
+++ b/tslib/src/functions-ps-report/ps-report-3b-stage-csv-file/ps-report-staging.data.service.ts
@@ -24,9 +24,11 @@ export class PsReportStagingDataService {
    */
   public async createAppendBlock (): Promise<void> {
     const containerService = this.blobService.getContainerClient(this.containerName)
+    // Create the container if missing
     await containerService.createIfNotExists()
     const appendBlobService = containerService.getAppendBlobClient(this.blobName)
-    await appendBlobService.create()
+    // Create the CSV file.
+    await appendBlobService.createIfNotExists()
   }
 
   /**
diff --git a/tslib/src/functions-ps-report/ps-report-4-writer/index.ts b/tslib/src/functions-ps-report/ps-report-4-writer/index.ts
index ccd65f12e0..3adeb12f91 100644
--- a/tslib/src/functions-ps-report/ps-report-4-writer/index.ts
+++ b/tslib/src/functions-ps-report/ps-report-4-writer/index.ts
@@ -4,7 +4,7 @@ import { PsReportWriterService } from './ps-report-writer.service'
 import { type PsReportStagingCompleteMessage } from '../common/ps-report-service-bus-messages'
 import { JobDataService } from '../../services/data/job.data.service'
 import { JobStatusCode } from '../../common/job-status-code'
-const funcName = 'ps-report-4-writer'
+let funcName = 'ps-report-4-writer'
 
 const serviceBusQueueTrigger: AzureFunction = async function (context: Context, incomingMessage: PsReportStagingCompleteMessage): Promise<void> {
   const start = performance.now()
@@ -16,12 +16,14 @@ const serviceBusQueueTrigger: AzureFunction = async function (context: Context,
 
 async function bulkUpload (context: Context, incomingMessage: PsReportStagingCompleteMessage): Promise<void> {
   let dbTable: string = ''
-  const service = new PsReportWriterService(context.log)
+  const service = new PsReportWriterService(context.log, context.invocationId)
   const jobDataService = new JobDataService()
+  funcName = funcName + ': ' + context.invocationId
   try {
     context.log.verbose(`${funcName}: creating new destination table in SQL Server`)
-    dbTable = await service.createDestinationTableAndView(incomingMessage)
+    dbTable = await service.createDestinationTableAndViewIfNotExists(incomingMessage)
     context.log.verbose(`${funcName}: new table created ${dbTable}`)
+
     await service.prepareForUpload(incomingMessage.filename)
     context.log(`${funcName}: starting bulk upload from ${incomingMessage.filename} into table ${dbTable}`)
     await service.bulkUpload(incomingMessage, dbTable) // the container is *known* and is stored in the location path of the database 'EXTERNAL DATA SOURCE'.
@@ -36,7 +38,8 @@ async function bulkUpload (context: Context, incomingMessage: PsReportStagingCom
       await jobDataService.setJobComplete(incomingMessage.jobUuid,
         JobStatusCode.Failed, JSON.stringify(error))
     }
-    await service.cleanup(incomingMessage.filename)
+    // Live debugging: 2024-05-31 for PS report. To be re-enabled.
+    // await service.cleanup(incomingMessage.filename)
   }
 }
 
diff --git a/tslib/src/functions-ps-report/ps-report-4-writer/ps-report-writer.service.ts b/tslib/src/functions-ps-report/ps-report-4-writer/ps-report-writer.service.ts
index 6efae4cdd3..41a5b0dd0e 100644
--- a/tslib/src/functions-ps-report/ps-report-4-writer/ps-report-writer.service.ts
+++ b/tslib/src/functions-ps-report/ps-report-4-writer/ps-report-writer.service.ts
@@ -5,30 +5,51 @@ import { BlobService } from '../../azure/blob-service'
 import * as mssql from 'mssql'
 import config from '../../config'
 import type { PsReportStagingCompleteMessage } from '../common/ps-report-service-bus-messages'
+import * as R from 'ramda'
+
 const containerName = 'ps-report-bulk-upload'
 
 export class PsReportWriterService {
   private readonly sqlService: ISqlService
   private readonly logger: ILogger
+  private readonly invocationId: string
   private readonly logServiceName = 'PsReportWriterService'
 
-  constructor (logger?: ILogger, sqlService?: ISqlService) {
-    if (logger === undefined) {
-      logger = new ConsoleLogger()
-    }
-    this.logger = logger
+  constructor (logger?: ILogger, invocationId?: string, sqlService?: ISqlService) {
+    this.logger = logger ?? new ConsoleLogger()
+    this.invocationId = invocationId ?? 'n/a'
+    this.sqlService = sqlService ?? new SqlService(this.logger)
+  }
+
+  public logPrefix (): string {
+    return `${this.logServiceName}: ${this.invocationId}`
+  }
 
-    if (sqlService === undefined) {
-      sqlService = new SqlService(this.logger)
+  public async tableExists (tableName: string): Promise<boolean> {
+    const sql = `
+    SELECT
+      *
+    FROM
+      information_schema.tables
+    WHERE
+      table_name = @name`
+
+    const params = [
+      { name: 'name', value: tableName, type: mssql.NVarChar }
+    ]
+    const res = this.sqlService.query(sql, params)
+    // empty: res => {}
+    if (R.isEmpty(res)) {
+      return true
     }
-    this.sqlService = sqlService
+    return false
   }
 
   /**
    *
    * @returns Create a new ps report table and return the table name
    */
-  public async createDestinationTableAndView (incomingMessage: PsReportStagingCompleteMessage): Promise<string> {
+  public async createDestinationTableAndViewIfNotExists (incomingMessage: PsReportStagingCompleteMessage): Promise<string> {
     let ds = moment().format('YYYY_MM_DDTHHmm') // default
     // Match 'ps-report-staging-2024-02-27-1510.csv'
     const matches = incomingMessage.filename.match(/\d\d\d\d-\d\d-\d\d-\d\d\d\d/)
@@ -36,6 +57,12 @@ export class PsReportWriterService {
       ds = matches[0].replaceAll('-', '_')
     }
     const newTableName = `psychometricReport_${ds}`
+
+    const tableExists = await this.tableExists(newTableName)
+    if (tableExists) {
+      throw new Error('Table already exists: ' + newTableName)
+    }
+
     const sql1 = `
       CREATE TABLE mtc_results.${newTableName} (
         PupilId int NOT NULL CONSTRAINT [PK_${newTableName}] PRIMARY KEY,
@@ -120,19 +147,19 @@ export class PsReportWriterService {
         PupilUPN ASC
       ) WITH ( PAD_INDEX = OFF,FILLFACTOR = 100,SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, STATISTICS_NORECOMPUTE = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON  ) ON [PRIMARY]
     `
-    this.logger.verbose(`${this.logServiceName}: creating table ${newTableName}`)
+    this.logger.verbose(`${this.logPrefix()}: creating table ${newTableName}`)
     await this.sqlService.modify(fullSql, [])
 
-    this.logger.verbose(`${this.logServiceName}: Creating trigger`)
+    this.logger.verbose(`${this.logPrefix()}: Creating trigger`)
     await this.sqlService.modify(triggerSql, [])
 
-    this.logger.verbose(`${this.logServiceName}: Creating IX1`)
+    this.logger.verbose(`${this.logPrefix()}: Creating IX1`)
     await this.sqlService.modify(ix1Sql, [])
 
-    this.logger.verbose(`${this.logServiceName}: Creating IX2`)
+    this.logger.verbose(`${this.logPrefix()}: Creating IX2`)
     await this.sqlService.modify(ix2Sql, [])
 
-    this.logger.info(`${this.logServiceName}: new table ${newTableName} created`)
+    this.logger.info(`${this.logPrefix()}: new table ${newTableName} created`)
 
     const viewSql = `
         CREATE OR ALTER VIEW [mtc_results].[vewPsychometricReport]
@@ -140,7 +167,7 @@ export class PsReportWriterService {
           SELECT * FROM [mtc_results].[${newTableName}]
     `
     await this.sqlService.modify(viewSql, [])
-    this.logger.info(`${this.logServiceName}: psychometricReport view recreated`)
+    this.logger.info(`${this.logPrefix()}: psychometricReport view recreated`)
     return newTableName
   }
 
@@ -151,7 +178,7 @@ export class PsReportWriterService {
   public async prepareForUpload (blobFile: string): Promise<void> {
     const blobService = new BlobService()
     const containerUrl = await blobService.getContainerUrl(containerName)
-    this.logger.verbose(`${this.logServiceName}: container url is ${containerUrl}`)
+    this.logger.verbose(`${this.logPrefix()}: container url is ${containerUrl}`)
     const sasToken = await blobService.getBlobReadWriteSasToken(containerName, blobFile)
     const sql = `
       IF (SELECT COUNT(*) FROM sys.database_scoped_credentials WHERE name = 'PsReportBulkUploadCredential') = 0
@@ -209,7 +236,7 @@ export class PsReportWriterService {
      * error in this block means we are running in Azure.
      */
     const result = await this.sqlService.query(sql2, [])
-    this.logger.verbose(`${this.logServiceName} OS is ${JSON.stringify(result)}`)
+    this.logger.verbose(`${this.logPrefix()}: OS is ${JSON.stringify(result)}`)
     let sqlConfig: mssql.config
 
     if (result[0].engineEdition === 'Enterprise' || result[0].engineEdition === 'Azure SQL Edge') {
@@ -255,14 +282,15 @@ export class PsReportWriterService {
           ROWTERMINATOR = '\r\n')
       ;`
     await mssql.query(sql)
-    await this.cleanup(sFilename)
+    // tmp
+    // await this.cleanup(sFilename)
   }
 
   public async cleanup (filename: string): Promise<void> {
-    this.logger.info(`${this.logServiceName}: cleanup() called`)
+    this.logger.info(`${this.logPrefix()}: cleanup() called`)
     // Remove CSV file
     const blobService = new BlobService()
     await blobService.deleteBlob(filename, containerName)
-    this.logger.info(`${this.logServiceName}: csv file ${filename} deleted.`)
+    this.logger.info(`${this.logPrefix()}: csv file ${filename} deleted.`)
   }
 }