Rajeev Pentyala – Microsoft power platform blog

    public void RetrieveUsingPFE()
    {
        // Retrieve 'Account' and 'Contact'. You can prepare your list of entities.
        var listEntities=new List<>{ "account", "contact" };
        var batchRequests = new List<OrganizationRequest>();            

        int pageNumber = 1;
        string pagingCookie = null;

        // Filter for Active records. You can prepare your required filters as below.
        var filterActive = new FilterExpression(LogicalOperator.And);
        var condActive = new ConditionExpression("statecode", ConditionOperator.Equal, 0);
        filterActive.AddCondition(condActive);

        try
        {
            foreach (var entity in listEntities)
            {
                // Prepare 'Query Expression'
                var query = new QueryExpression(entity)
                {
                    ColumnSet = new ColumnSet(true),
                    PageInfo = new PagingInfo()
                };
                query.PageInfo.Count = 5000;
                query.PageInfo.PageNumber = pageNumber;
                query.PageInfo.PagingCookie = pagingCookie;

                query.Criteria.AddFilter(filterActive);

                var request = new RetrieveMultipleRequest
                {
                    Query = query
                };

                batchRequests.Add(request);
            }

            do
            {
                // Trigger Pfe.Execute
                var batchResponses = TriggerRequests(batchRequests);
                batchRequests = new List<OrganizationRequest>();
                pageNumber++;
                foreach (var responseItem in batchResponses)
                {
                    if (responseItem.EntityCollection.Entities.Count > 0)
                    {                            
                        var currEntityName = responseItem.EntityCollection.Entities[0].LogicalName;

                        foreach (var record in responseItem.EntityCollection.Entities)
                        {
                            // 'record' is the Retreieved record
                            // Perform your desired operations
                        }
                    }

                    if (responseItem.EntityCollection.MoreRecords)
                    {
                        var query = new QueryExpression(responseItem.EntityCollection.EntityName)
                        {
                            ColumnSet = new ColumnSet(true)
                        };

                        query.Criteria.AddFilter(filterActive);

                        var request = new RetrieveMultipleRequest();
                        query.PageInfo = new PagingInfo
                        {
                            Count = 5000,
                            PageNumber = pageNumber,
                            PagingCookie = responseItem.EntityCollection.PagingCookie
                        };

                        request.Query = query;
                        batchRequests.Add(request);
                    }
                }
            } while (batchRequests.Count > 0);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error occurred, error message is {0}", ex.Message);
            throw ex;
        }            
    }

    public List<RetrieveMultipleResponse> TriggerRequests(List<OrganizationRequest> batchRequests)
    {
        var recordsPerRequest = 1; // Set your desired value.
        var retrieveRequestBatches = batchRequests.AsBatches(recordsPerRequest);
        var batchResponses = ExecuteParallelProxy(retrieveRequestBatches);            
        var listResponses = new List<RetrieveMultipleResponse>();

        foreach (var key in batchResponses.Keys)
        {
            foreach (var result in batchResponses[key].Responses)
            {
                if (retrieveRequestBatches[key].Requests[result.RequestIndex] is RetrieveMultipleRequest)
                {
                    var originalRequest = (RetrieveMultipleRequest)retrieveRequestBatches[key].Requests[result.RequestIndex];
                    // Capture failed records
                    if (result.Fault != null)
                    {
                        Console.WriteLine($" Exception : {result.Fault.Message}");
                    }
                    else if (result.Response != null && result.Response is RetrieveMultipleResponse) // Capture success records
                    {
                        var responseItem = (RetrieveMultipleResponse)result.Response;
                        listResponses.Add(responseItem);
                    }
                }                    
            }
        }

        return listResponses;
    }

    private IDictionary<string, ExecuteMultipleResponse> ExecuteParallelProxy(IDictionary<string, ExecuteMultipleRequest> retrieveRequestBatches)
    {            
        IDictionary<string, ExecuteMultipleResponse> batchResponses = null;
        try
        {
            batchResponses = CRMPfeConnection.ParallelProxy.Execute<ExecuteMultipleRequest, ExecuteMultipleResponse>(retrieveRequestBatches);                
        }
        catch (AggregateException ae)
        {
            foreach (var ex in ae.InnerExceptions)
            {
                Console.WriteLine($"Aggregate Error in ExecuteParallelProxy : {ex.Message.ToString()}");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error in ExecuteParallelProxy : {ex.Message.ToString()}");
        }

        return batchResponses;
    }

    public static OrganizationServiceManager CRMPfeConnection
    {
        get
        {
            if (crmPfeConnection == null)
            {
                var UserName = ConfigurationManager.AppSettings["UserNameSrc"].ToString();
                var Password = ConfigurationManager.AppSettings["PasswordSrc"].ToString();
                var OrganizationUri = ConfigurationManager.AppSettings["OrganizationUriSrc"].ToString();
                ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;
          crmPfeConnection = new OrganizationServiceManager(XrmServiceUriFactory.CreateOrganizationServiceUri(OrganizationUri), UserName, Password);
            }
            return crmPfeConnection;
        }
    }