diff --git a/console.go b/console.go
index f460cf1..f034c75 100644
--- a/console.go
+++ b/console.go
@@ -157,7 +157,7 @@ func ConsoleHandler(w http.ResponseWriter, r *http.Request) {
 					return
 				} else {
 					tasks = tl
-					taskKeys = makeTaskKeys(ds, job.FirstTaskId, job.TaskCount)
+					taskKeys = makeTaskKeys(ds, job.Id, job.FirstTaskId, job.TaskCount)
 				}
 			default:
 				jobKey := ds.NewKey(JobEntity, "", id, nil)
diff --git a/map.go b/map.go
index 2f7de5b..3c22e16 100644
--- a/map.go
+++ b/map.go
@@ -67,12 +67,7 @@ func mapMonitorTask(c context.Context, ds appwrap.Datastore, pipeline MapReduceP
 		}
 	}
 
-	firstId, err := mkIds(ds, TaskEntity, len(job.WriterNames))
-	if err != nil {
-		jobFailed(c, ds, pipeline, jobKey, fmt.Errorf("failed to allocate ids for reduce tasks: %s", err.Error()), log)
-		return 200
-	}
-	taskKeys := makeTaskKeys(ds, firstId, len(job.WriterNames))
+	taskKeys := makeTaskKeys(ds, job.Id, 0, len(job.WriterNames))
 	tasks := make([]JobTask, 0, len(job.WriterNames))
 
 	for shard := range job.WriterNames {
@@ -80,8 +75,6 @@ func mapMonitorTask(c context.Context, ds appwrap.Datastore, pipeline MapReduceP
 			url := fmt.Sprintf("%s/reduce?taskKey=%s;shard=%d;writer=%s",
 				job.UrlPrefix, taskKeys[len(tasks)].Encode(), shard, url.QueryEscape(job.WriterNames[shard]))
 
-			firstId++
-
 			shardJson, _ := json.Marshal(shards)
 			shardZ := &bytes.Buffer{}
 			w := zlib.NewWriter(shardZ)
diff --git a/mapreduce.go b/mapreduce.go
index 016f213..85cd060 100644
--- a/mapreduce.go
+++ b/mapreduce.go
@@ -18,7 +18,6 @@ package mapreduce
 import (
 	"fmt"
 	"net/http"
-	"sort"
 	"strings"
 	"time"
 
@@ -159,12 +158,7 @@ func Run(c context.Context, ds appwrap.Datastore, job MapReduceJob) (int64, erro
 		return 0, fmt.Errorf("creating job: %s", err)
 	}
 
-	firstId, err := mkIds(ds, TaskEntity, len(readerNames))
-	if err != nil {
-		return 0, fmt.Errorf("allocating keys: %s", err)
-	}
-
-	taskKeys := makeTaskKeys(ds, firstId, len(readerNames))
+	taskKeys := makeTaskKeys(ds, appwrap.KeyIntID(jobKey), 0, len(readerNames))
 	tasks := make([]JobTask, len(readerNames))
 
 	for i, readerName := range readerNames {
@@ -303,29 +297,3 @@ func tryAgainIfNonFatal(err error) error {
 	}
 	return nil
 }
-
-func mkIds(ds appwrap.Datastore, kind string, count int) (int64, error) {
-	incomplete := make([]*appwrap.DatastoreKey, count)
-	for i := range incomplete {
-		incomplete[i] = ds.NewKey(kind, "", 0, nil)
-	}
-
-	if completeKeys, err := ds.AllocateIDSet(incomplete); err != nil {
-		return 0, fmt.Errorf("reserving keys: %s", err)
-	} else {
-		ids := make([]int, len(completeKeys))
-		for i, k := range completeKeys {
-			ids[i] = int(appwrap.KeyIntID(k))
-		}
-
-		sort.Sort(sort.IntSlice(ids))
-
-		for i := 0; i < len(ids) - 1; i++ {
-			if ids[i] != ids[i+1]-1 {
-				return 0, fmt.Errorf("nonconsecutive keys allocated")
-			}
-		}
-
-		return int64(ids[0]), nil
-	}
-}
diff --git a/tasks.go b/tasks.go
index e92eeb2..ff6bf11 100644
--- a/tasks.go
+++ b/tasks.go
@@ -70,7 +70,7 @@ type JobInfo struct {
 	UpdatedAt           time.Time
 	StartTime           time.Time
 	TaskCount           int      `datastore:"TasksRunning,noindex"`
-	FirstTaskId         int64    `datastore:",noindex"`
+	FirstTaskId         int64    `datastore:",noindex"` // 0 here means to use task keys like "%d.%d" (Id, taskNum)
 	RetryCount          int      `datastore:",noindex"`
 	SeparateReduceItems bool     `datastore:",noindex"`
 	OnCompleteUrl       string   `datastore:",noindex"`
@@ -181,7 +181,7 @@ func createTasks(ds appwrap.Datastore, jobKey *appwrap.DatastoreKey, taskKeys []
 			}
 
 			job.TaskCount = len(tasks)
-			job.FirstTaskId = firstId
+			job.FirstTaskId = 0 // use new style ids
 			job.Stage = newStage
 
 			_, err := ds.Put(jobKey, &job)
@@ -284,6 +284,7 @@ func jobStageComplete(ds appwrap.Datastore, jobKey *appwrap.DatastoreKey, taskKe
 
 		job.Stage = nextStage
 		job.UpdatedAt = time.Now()
+		job.Id = appwrap.KeyIntID(jobKey)
 
 		_, err := ds.Put(jobKey, &job)
 		stageChanged = (err == nil)
@@ -443,17 +444,23 @@ func RemoveJob(ds appwrap.Datastore, jobId int64) error {
 	return nil
 }
 
-func makeTaskKeys(ds appwrap.Datastore, firstId int64, count int) []*appwrap.DatastoreKey {
+func makeTaskKeys(ds appwrap.Datastore, jobId int64, firstId int64, count int) []*appwrap.DatastoreKey {
 	taskKeys := make([]*appwrap.DatastoreKey, count)
-	for i := 0; i < count; i++ {
-		taskKeys[i] = ds.NewKey(TaskEntity, "", firstId+int64(i), nil)
+	if firstId == 0 {
+		for i := 0; i < count; i++ {
+			taskKeys[i] = ds.NewKey(TaskEntity, fmt.Sprintf("%d.task%d", jobId, i), 0, nil)
+		}
+	} else {
+		for i := 0; i < count; i++ {
+			taskKeys[i] = ds.NewKey(TaskEntity, "", firstId+int64(i), nil)
+		}
 	}
 
 	return taskKeys
 }
 
 func gatherTasks(ds appwrap.Datastore, job JobInfo) ([]JobTask, error) {
-	taskKeys := makeTaskKeys(ds, job.FirstTaskId, job.TaskCount)
+	taskKeys := makeTaskKeys(ds, job.Id, job.FirstTaskId, job.TaskCount)
 	tasks := make([]JobTask, len(taskKeys))
 
 	i := 0
@@ -557,7 +564,7 @@ func doWaitForStageCompletion(c context.Context, ds appwrap.Datastore, taskIntf
 		return JobInfo{}, err
 	} else {
 		job = j
-		taskKeys = makeTaskKeys(ds, job.FirstTaskId, job.TaskCount)
+		taskKeys = makeTaskKeys(ds, job.Id, job.FirstTaskId, job.TaskCount)
 	}
 
 	start := time.Now()