Update shard retention time when policy changes

Fixes issue #3702.

meta/data.go

@@ -212,6 +212,7 @@ func (data *Data) UpdateRetentionPolicy(database, name string, rpu *RetentionPol
 	}
 	if rpu.Duration != nil {
 		rpi.Duration = *rpu.Duration
+		rpi.ShardGroupDuration = shardGroupDuration(rpi.Duration)
 	}
 	if rpu.ReplicaN != nil {
 		rpi.ReplicaN = *rpu.ReplicaN

meta/data_test.go

@@ -178,7 +178,7 @@ func TestData_UpdateRetentionPolicy(t *testing.T) {
 	if rpi, _ := data.RetentionPolicy("db0", "rp1"); !reflect.DeepEqual(rpi, &meta.RetentionPolicyInfo{
 		Name:               "rp1",
 		Duration:           10 * time.Hour,
-		ShardGroupDuration: 604800000000000,
+		ShardGroupDuration: 3600000000000,
 		ReplicaN:           3,
 	}) {
 		t.Fatalf("unexpected policy: %#v", rpi)

meta/store_test.go

@@ -361,7 +361,7 @@ func TestStore_UpdateRetentionPolicy(t *testing.T) {
 	} else if !reflect.DeepEqual(rpi, &meta.RetentionPolicyInfo{
 		Name:               "rp1",
 		Duration:           10 * time.Hour,
-		ShardGroupDuration: 7 * 24 * time.Hour,
+		ShardGroupDuration: 1 * time.Hour,
 		ReplicaN:           1,
 	}) {
 		t.Fatalf("unexpected policy: %#v", rpi)