// TestTxnCoordSenderCleanupOnAborted verifies that if a txn receives a
// TransactionAbortedError, the coordinator cleans up the transaction.
func TestTxnCoordSenderCleanupOnAborted(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()

	// Create a transaction with intent at "a".
	key := roachpb.Key("a")
	txn1 := client.NewTxn(context.Background(), *s.DB)
	txn1.InternalSetPriority(1)
	if err := txn1.Put(key, []byte("value")); err != nil {
		t.Fatal(err)
	}

	// Push the transaction (by writing key "a" with higher priority) to abort it.
	txn2 := client.NewTxn(context.Background(), *s.DB)
	txn2.InternalSetPriority(2)
	if err := txn2.Put(key, []byte("value2")); err != nil {
		t.Fatal(err)
	}

	// Now end the transaction and verify we've cleanup up, even though
	// end transaction failed.
	err := txn1.CommitOrCleanup()
	assertTransactionAbortedError(t, err)
	if err := txn2.CommitOrCleanup(); err != nil {
		t.Fatal(err)
	}
	verifyCleanup(key, sender, s.Eng, t)
}

// TestTxnCoordSenderBeginTransaction verifies that a command sent with a
// not-nil Txn with empty ID gets a new transaction initialized.
func TestTxnCoordSenderBeginTransaction(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(sender)

	txn := client.NewTxn(context.Background(), *s.DB)

	// Put request will create a new transaction.
	key := roachpb.Key("key")
	txn.InternalSetPriority(10)
	txn.Proto.Isolation = enginepb.SNAPSHOT
	txn.Proto.Name = "test txn"
	if err := txn.Put(key, []byte("value")); err != nil {
		t.Fatal(err)
	}
	if txn.Proto.Name != "test txn" {
		t.Errorf("expected txn name to be %q; got %q", "test txn", txn.Proto.Name)
	}
	if txn.Proto.Priority != 10 {
		t.Errorf("expected txn priority 10; got %d", txn.Proto.Priority)
	}
	if !bytes.Equal(txn.Proto.Key, key) {
		t.Errorf("expected txn Key to match %q != %q", key, txn.Proto.Key)
	}
	if txn.Proto.Isolation != enginepb.SNAPSHOT {
		t.Errorf("expected txn isolation to be SNAPSHOT; got %s", txn.Proto.Isolation)
	}
}

// TestTxnCoordSenderAddIntentOnError verifies that intents are tracked if
// the transaction is, even on error.
func TestTxnCoordSenderAddIntentOnError(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()

	// Create a transaction with intent at "a".
	key := roachpb.Key("x")
	txn := client.NewTxn(context.Background(), *s.DB)
	// Write so that the coordinator begins tracking this txn.
	if err := txn.Put("x", "y"); err != nil {
		t.Fatal(err)
	}
	err, ok := txn.CPut(key, []byte("x"), []byte("born to fail")).(*roachpb.ConditionFailedError)
	if !ok {
		t.Fatal(err)
	}
	sender.Lock()
	txnID := *txn.Proto.ID
	roachpb.MergeSpans(&sender.txns[txnID].keys)
	intentSpans := sender.txns[txnID].keys
	expSpans := []roachpb.Span{{Key: key, EndKey: []byte("")}}
	equal := !reflect.DeepEqual(intentSpans, expSpans)
	sender.Unlock()
	if err := txn.Rollback(); err != nil {
		t.Fatal(err)
	}
	if !equal {
		t.Fatalf("expected stored intents %v, got %v", expSpans, intentSpans)
	}
}

// TestTxnCoordIdempotentCleanup verifies that cleanupTxnLocked is idempotent.
func TestTxnCoordIdempotentCleanup(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(sender)

	txn := client.NewTxn(context.Background(), *s.DB)
	ba := txn.NewBatch()
	ba.Put(roachpb.Key("a"), []byte("value"))
	if err := txn.Run(ba); err != nil {
		t.Fatal(err)
	}

	sender.Lock()
	// Clean up twice successively.
	sender.cleanupTxnLocked(context.Background(), txn.Proto)
	sender.cleanupTxnLocked(context.Background(), txn.Proto)
	sender.Unlock()

	// For good measure, try to commit (which cleans up once more if it
	// succeeds, which it may not if the previous cleanup has already
	// terminated the heartbeat goroutine)
	ba = txn.NewBatch()
	ba.AddRawRequest(&roachpb.EndTransactionRequest{})
	err := txn.Run(ba)
	if err != nil && !testutils.IsError(err, errNoState.Error()) {
		t.Fatal(err)
	}
}

// TestTxnInitialTimestamp verifies that the timestamp requested
// before the Txn is created is honored.
func TestTxnInitialTimestamp(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(sender)

	txn := client.NewTxn(context.Background(), *s.DB)

	// Request a specific timestamp.
	refTimestamp := hlc.Timestamp{WallTime: 42, Logical: 69}
	txn.Proto.OrigTimestamp = refTimestamp

	// Put request will create a new transaction.
	key := roachpb.Key("key")
	txn.InternalSetPriority(10)
	txn.Proto.Isolation = enginepb.SNAPSHOT
	txn.Proto.Name = "test txn"
	if err := txn.Put(key, []byte("value")); err != nil {
		t.Fatal(err)
	}
	if txn.Proto.OrigTimestamp != refTimestamp {
		t.Errorf("expected txn orig ts to be %s; got %s", refTimestamp, txn.Proto.OrigTimestamp)
	}
	if txn.Proto.Timestamp != refTimestamp {
		t.Errorf("expected txn ts to be %s; got %s", refTimestamp, txn.Proto.Timestamp)
	}
}

// TestTxnCoordSenderGCTimeout verifies that the coordinator cleans up extant
// transactions and intents after the lastUpdateNanos exceeds the timeout.
func TestTxnCoordSenderGCTimeout(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()

	// Set heartbeat interval to 1ms for testing.
	sender.heartbeatInterval = 1 * time.Millisecond

	txn := client.NewTxn(context.Background(), *s.DB)
	key := roachpb.Key("a")
	if err := txn.Put(key, []byte("value")); err != nil {
		t.Fatal(err)
	}

	// Now, advance clock past the default client timeout.
	// Locking the TxnCoordSender to prevent a data race.
	sender.Lock()
	s.Manual.Set(defaultClientTimeout.Nanoseconds() + 1)
	sender.Unlock()

	txnID := *txn.Proto.ID

	util.SucceedsSoon(t, func() error {
		// Locking the TxnCoordSender to prevent a data race.
		sender.Lock()
		_, ok := sender.txns[txnID]
		sender.Unlock()
		if ok {
			return errors.Errorf("expected garbage collection")
		}
		return nil
	})

	verifyCleanup(key, sender, s.Eng, t)
}

// reset creates a new Txn and initializes it using the session defaults.
func (ts *txnState) reset(ctx context.Context, e *Executor, s *Session) {
	*ts = txnState{}
	ts.txn = client.NewTxn(ctx, *e.ctx.DB)
	ts.txn.Proto.Isolation = s.DefaultIsolationLevel
	ts.tr = s.Trace
	// Discard the old schemaChangers, if any.
	ts.schemaChangers = schemaChangerCollection{}
}

func (ds *ServerImpl) setupTxn(
	ctx context.Context,
	txnProto *roachpb.Transaction,
) *client.Txn {
	txn := client.NewTxn(ctx, *ds.ctx.DB)
	// TODO(radu): we should sanity check some of these fields
	txn.Proto = *txnProto
	return txn
}

// Prepare returns the result types of the given statement. pinfo may
// contain partial type information for placeholders. Prepare will
// populate the missing types. The column result types are returned (or
// nil if there are no results).
func (e *Executor) Prepare(
	query string,
	session *Session,
	pinfo parser.PlaceholderTypes,
) ([]ResultColumn, error) {
	if log.V(2) {
		log.Infof(session.Ctx(), "preparing: %s", query)
	} else if traceSQL {
		log.Tracef(session.Ctx(), "preparing: %s", query)
	}
	stmt, err := parser.ParseOne(query, parser.Syntax(session.Syntax))
	if err != nil {
		return nil, err
	}
	if err = pinfo.ProcessPlaceholderAnnotations(stmt); err != nil {
		return nil, err
	}
	protoTS, err := isAsOf(&session.planner, stmt, e.ctx.Clock.Now())
	if err != nil {
		return nil, err
	}

	session.planner.resetForBatch(e)
	session.planner.semaCtx.Placeholders.SetTypes(pinfo)
	session.planner.evalCtx.PrepareOnly = true

	// Prepare needs a transaction because it needs to retrieve db/table
	// descriptors for type checking.
	txn := client.NewTxn(session.Ctx(), *e.ctx.DB)
	txn.Proto.Isolation = session.DefaultIsolationLevel
	session.planner.setTxn(txn)
	defer session.planner.setTxn(nil)

	if protoTS != nil {
		session.planner.asOf = true
		defer func() {
			session.planner.asOf = false
		}()

		setTxnTimestamps(txn, *protoTS)
	}

	plan, err := session.planner.prepare(stmt)
	if err != nil {
		return nil, err
	}
	if plan == nil {
		return nil, nil
	}
	cols := plan.Columns()
	for _, c := range cols {
		if err := checkResultDatum(c.Typ); err != nil {
			return nil, err
		}
	}
	return cols, nil
}

// TestTxnCoordSenderMultipleTxns verifies correct operation with
// multiple outstanding transactions.
func TestTxnCoordSenderMultipleTxns(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(sender)

	txn1 := client.NewTxn(context.Background(), *s.DB)
	txn2 := client.NewTxn(context.Background(), *s.DB)

	if err := txn1.Put(roachpb.Key("a"), []byte("value")); err != nil {
		t.Fatal(err)
	}
	if err := txn2.Put(roachpb.Key("b"), []byte("value")); err != nil {
		t.Fatal(err)
	}

	if len(sender.txns) != 2 {
		t.Errorf("expected length of transactions map to be 2; got %d", len(sender.txns))
	}
}

// Restore imports a SQL table (or all user SQL tables) from a set of
// non-overlapping sstable files.
func Restore(ctx context.Context, db client.DB, base string, table string, overwrite bool) error {
	sst, err := engine.MakeRocksDBSstFileReader()
	if err != nil {
		return err
	}
	defer sst.Close()

	descBytes, err := ioutil.ReadFile(filepath.Join(base, backupDescriptorName))
	if err != nil {
		return err
	}
	var backupDesc sqlbase.BackupDescriptor
	if err := backupDesc.Unmarshal(descBytes); err != nil {
		return err
	}
	for _, r := range backupDesc.Ranges {
		if len(r.Path) == 0 {
			continue
		}
		if err := sst.AddFile(r.Path); err != nil {
			return err
		}
	}

	// TODO(dan): This uses one giant transaction for the entire restore, which
	// works for small datasets, but not for big ones.
	txn := client.NewTxn(ctx, db)
	if len(table) > 0 {
		found := false
		for _, desc := range backupDesc.SQL {
			if t := desc.GetTable(); t != nil && t.Name == table {
				if err := restoreTable(ctx, sst, txn, t, overwrite); err != nil {
					return err
				}
				found = true
				break
			}
		}
		if !found {
			return errors.Errorf("table not found: %s", table)
		}
	} else {
		for _, desc := range backupDesc.SQL {
			if t := desc.GetTable(); t != nil && t.ParentID != keys.SystemDatabaseID {
				if err := restoreTable(ctx, sst, txn, t, overwrite); err != nil {
					return err
				}
			}
		}
	}
	return txn.CommitOrCleanup()
}

// TestTxnCoordSenderKeyRanges verifies that multiple requests to same or
// overlapping key ranges causes the coordinator to keep track only of
// the minimum number of ranges.
func TestTxnCoordSenderKeyRanges(t *testing.T) {
	defer leaktest.AfterTest(t)()
	ranges := []struct {
		start, end roachpb.Key
	}{
		{roachpb.Key("a"), roachpb.Key(nil)},
		{roachpb.Key("a"), roachpb.Key(nil)},
		{roachpb.Key("aa"), roachpb.Key(nil)},
		{roachpb.Key("b"), roachpb.Key(nil)},
		{roachpb.Key("aa"), roachpb.Key("c")},
		{roachpb.Key("b"), roachpb.Key("c")},
	}

	s, sender := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(sender)

	txn := client.NewTxn(context.Background(), *s.DB)
	for _, rng := range ranges {
		if rng.end != nil {
			if err := txn.DelRange(rng.start, rng.end); err != nil {
				t.Fatal(err)
			}
		} else {
			if err := txn.Put(rng.start, []byte("value")); err != nil {
				t.Fatal(err)
			}
		}
	}

	txnID := *txn.Proto.ID

	// Verify that the transaction metadata contains only two entries
	// in its "keys" range group. "a" and range "aa"-"c".
	txnMeta, ok := sender.txns[txnID]
	if !ok {
		t.Fatalf("expected a transaction to be created on coordinator")
	}
	roachpb.MergeSpans(&txnMeta.keys)
	keys := txnMeta.keys
	if len(keys) != 2 {
		t.Errorf("expected 2 entries in keys range group; got %v", keys)
	}
}

// TestTxnCoordSenderReleaseTxnMeta verifies that TxnCoordSender releases the
// txnMetadata after the txn has committed successfully.
func TestTxnCoordSenderReleaseTxnMeta(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(sender)

	txn := client.NewTxn(context.Background(), *s.DB)
	ba := txn.NewBatch()
	ba.Put(roachpb.Key("a"), []byte("value"))
	ba.Put(roachpb.Key("b"), []byte("value"))
	if err := txn.CommitInBatch(ba); err != nil {
		t.Fatal(err)
	}

	txnID := *txn.Proto.ID

	if _, ok := sender.txns[txnID]; ok {
		t.Fatal("expected TxnCoordSender has released the txn")
	}
}

// TestTxnCoordSenderBeginTransactionMinPriority verifies that when starting
// a new transaction, a non-zero priority is treated as a minimum value.
func TestTxnCoordSenderBeginTransactionMinPriority(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(sender)

	txn := client.NewTxn(context.Background(), *s.DB)

	// Put request will create a new transaction.
	key := roachpb.Key("key")
	txn.InternalSetPriority(10)
	txn.Proto.Isolation = enginepb.SNAPSHOT
	txn.Proto.Priority = 11
	if err := txn.Put(key, []byte("value")); err != nil {
		t.Fatal(err)
	}
	if prio := txn.Proto.Priority; prio != 11 {
		t.Errorf("expected txn priority 11; got %d", prio)
	}
}

// reset creates a new Txn and initializes it using the session defaults.
func (ts *txnState) reset(ctx context.Context, e *Executor, s *Session) {
	*ts = txnState{}
	ts.txn = client.NewTxn(ctx, *e.ctx.DB)
	ts.txn.Context = s.context
	ts.txn.Proto.Isolation = s.DefaultIsolationLevel
	ts.tr = s.Trace
	// Discard the old schemaChangers, if any.
	ts.schemaChangers = schemaChangerCollection{}

	if traceSQL {
		sp, err := tracing.JoinOrNewSnowball("coordinator", nil, func(sp basictracer.RawSpan) {
			ts.txn.CollectedSpans = append(ts.txn.CollectedSpans, sp)
		})
		if err != nil {
			log.Warningf(ctx, "unable to create snowball tracer: %s", err)
			return
		}
		ts.txn.Context = opentracing.ContextWithSpan(ts.txn.Context, sp)
		ts.sp = sp
	}
}

// TestReadOnlyTxnObeysDeadline tests that read-only transactions obey the
// deadline.
func TestReadOnlyTxnObeysDeadline(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, _, _ := serverutils.StartServer(t, base.TestServerArgs{})
	defer s.Stopper().Stop()
	db := createTestClient(t, s.Stopper(), s.ServingAddr())

	if err := db.Put("k", "v"); err != nil {
		t.Fatal(err)
	}

	// Use txn.Exec instead of db.Txn to disable auto retry.
	txn := client.NewTxn(context.TODO(), *db)
	if err := txn.Exec(client.TxnExecOptions{AutoRetry: false, AutoCommit: true}, func(txn *client.Txn, _ *client.TxnExecOptions) error {
		// Set deadline to sometime in the past.
		txn.UpdateDeadlineMaybe(hlc.Timestamp{WallTime: timeutil.Now().Add(-time.Second).UnixNano()})
		_, err := txn.Get("k")
		return err
	}); !testutils.IsError(err, "txn aborted") {
		t.Fatal(err)
	}
}

func TestTxnCoordSenderCancel(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()

	ctx, cancel := context.WithCancel(context.Background())

	origSender := sender.wrapped
	sender.wrapped = client.SenderFunc(
		func(ctx context.Context, args roachpb.BatchRequest) (*roachpb.BatchResponse, *roachpb.Error) {
			if _, hasET := args.GetArg(roachpb.EndTransaction); hasET {
				// Cancel the transaction while also sending it along. This tickled a
				// data race in TxnCoordSender.tryAsyncAbort. See #7726.
				cancel()
			}
			return origSender.Send(ctx, args)
		})

	// Create a transaction with bunch of intents.
	txn := client.NewTxn(ctx, *s.DB)
	batch := txn.NewBatch()
	for i := 0; i < 100; i++ {
		key := roachpb.Key(fmt.Sprintf("%d", i))
		batch.Put(key, []byte("value"))
	}
	if err := txn.Run(batch); err != nil {
		t.Fatal(err)
	}

	// Commit the transaction. Note that we cancel the transaction when the
	// commit is sent which stresses the TxnCoordSender.tryAsyncAbort code
	// path. We'll either succeed, get a "does not exist" error, or get a
	// context canceled error. Anything else is unexpected.
	err := txn.CommitOrCleanup()
	if err != nil && err.Error() != context.Canceled.Error() &&
		!testutils.IsError(err, "does not exist") {
		t.Fatal(err)
	}
}

// TestTxnCoordSenderAddRequest verifies adding a request creates a
// transaction metadata and adding multiple requests with same
// transaction ID updates the last update timestamp.
func TestTxnCoordSenderAddRequest(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sender := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(sender)

	txn := client.NewTxn(context.Background(), *s.DB)

	// Put request will create a new transaction.
	if err := txn.Put(roachpb.Key("a"), []byte("value")); err != nil {
		t.Fatal(err)
	}
	txnID := *txn.Proto.ID
	txnMeta, ok := sender.txns[txnID]
	if !ok {
		t.Fatal("expected a transaction to be created on coordinator")
	}
	if !txn.Proto.Writing {
		t.Fatal("txn is not marked as writing")
	}
	ts := atomic.LoadInt64(&txnMeta.lastUpdateNanos)

	// Advance time and send another put request. Lock the coordinator
	// to prevent a data race.
	sender.Lock()
	s.Manual.Set(1)
	sender.Unlock()
	if err := txn.Put(roachpb.Key("a"), []byte("value")); err != nil {
		t.Fatal(err)
	}
	if len(sender.txns) != 1 {
		t.Errorf("expected length of transactions map to be 1; got %d", len(sender.txns))
	}
	txnMeta = sender.txns[txnID]
	if lu := atomic.LoadInt64(&txnMeta.lastUpdateNanos); ts >= lu || lu != s.Manual.UnixNano() {
		t.Errorf("expected last update time to advance; got %d", lu)
	}
}

func TestTxnRestartCount(t *testing.T) {
	defer leaktest.AfterTest(t)()
	_, sender, cleanupFn := setupMetricsTest(t)
	defer cleanupFn()

	key := []byte("key-restart")
	value := []byte("value")
	db := client.NewDB(sender)

	// Start a transaction and do a GET. This forces a timestamp to be chosen for the transaction.
	txn := client.NewTxn(context.Background(), *db)
	if _, err := txn.Get(key); err != nil {
		t.Fatal(err)
	}

	// Outside of the transaction, read the same key as was read within the transaction. This
	// means that future attempts to write will increase the timestamp.
	if _, err := db.Get(key); err != nil {
		t.Fatal(err)
	}

	// This put will lay down an intent, txn timestamp will increase beyond original.
	if err := txn.Put(key, value); err != nil {
		t.Fatal(err)
	}
	if !txn.Proto.OrigTimestamp.Less(txn.Proto.Timestamp) {
		t.Errorf("expected timestamp to increase: %s", txn.Proto)
	}

	// Commit (should cause restart metric to increase).
	err := txn.CommitOrCleanup()
	assertTransactionRetryError(t, err)

	teardownHeartbeats(sender)
	checkTxnMetrics(t, sender, "restart txn", 0, 0, 0, 1, 1)
}

//.........这里部分代码省略.........
					}},
				},
			},
			referenced: []TableDescriptor{{
				ID:   52,
				Name: "baz",
			}},
		},
		{
			err: `missing interleave back reference to foo.bar from baz.qux`,
			desc: TableDescriptor{
				ID:   51,
				Name: "foo",
				PrimaryIndex: IndexDescriptor{
					ID:   1,
					Name: "bar",
					Interleave: InterleaveDescriptor{Ancestors: []InterleaveDescriptor_Ancestor{
						{TableID: 52, IndexID: 2},
					}},
				},
			},
			referenced: []TableDescriptor{{
				ID:   52,
				Name: "baz",
				PrimaryIndex: IndexDescriptor{
					ID:   2,
					Name: "qux",
				},
			}},
		},
		{
			err: `invalid interleave backreference table=52 index=2: descriptor not found`,
			desc: TableDescriptor{
				ID: 51,
				PrimaryIndex: IndexDescriptor{
					ID:            1,
					InterleavedBy: []ForeignKeyReference{{Table: 52, Index: 2}},
				},
			},
		},
		{
			err: `invalid interleave backreference table=baz index=2: index-id "2" does not exist`,
			desc: TableDescriptor{
				ID: 51,
				PrimaryIndex: IndexDescriptor{
					ID:            1,
					InterleavedBy: []ForeignKeyReference{{Table: 52, Index: 2}},
				},
			},
			referenced: []TableDescriptor{{
				ID:   52,
				Name: "baz",
			}},
		},
		{
			err: `broken interleave backward reference from foo.bar to baz.qux`,
			desc: TableDescriptor{
				ID:   51,
				Name: "foo",
				PrimaryIndex: IndexDescriptor{
					ID:            1,
					Name:          "bar",
					InterleavedBy: []ForeignKeyReference{{Table: 52, Index: 2}},
				},
			},
			referenced: []TableDescriptor{{
				ID:   52,
				Name: "baz",
				PrimaryIndex: IndexDescriptor{
					ID:   2,
					Name: "qux",
				},
			}},
		},
	}

	for i, test := range tests {
		for _, referencedDesc := range test.referenced {
			var v roachpb.Value
			desc := &Descriptor{Union: &Descriptor_Table{Table: &referencedDesc}}
			if err := v.SetProto(desc); err != nil {
				t.Fatal(err)
			}
			if err := kvDB.Put(MakeDescMetadataKey(referencedDesc.ID), &v); err != nil {
				t.Fatal(err)
			}
		}
		txn := client.NewTxn(context.Background(), *kvDB)
		if err := test.desc.validateCrossReferences(txn); err == nil {
			t.Errorf("%d: expected \"%s\", but found success: %+v", i, test.err, test.desc)
		} else if test.err != err.Error() {
			t.Errorf("%d: expected \"%s\", but found \"%s\"", i, test.err, err.Error())
		}
		for _, referencedDesc := range test.referenced {
			if err := kvDB.Del(MakeDescMetadataKey(referencedDesc.ID)); err != nil {
				t.Fatal(err)
			}
		}
	}
}