// 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 := createTestDB(t)
	defer s.Stop()
	defer teardownHeartbeats(s.Sender)

	reply := &proto.PutResponse{}
	s.Sender.Send(context.Background(), proto.Call{
		Args: &proto.PutRequest{
			RequestHeader: proto.RequestHeader{
				Key:          proto.Key("key"),
				User:         security.RootUser,
				UserPriority: gogoproto.Int32(-10), // negative user priority is translated into positive priority
				Txn: &proto.Transaction{
					Name:      "test txn",
					Isolation: proto.SNAPSHOT,
					Priority:  11,
				},
			},
		},
		Reply: reply,
	})
	if reply.Error != nil {
		t.Fatal(reply.GoError())
	}
	if reply.Txn.Priority != 11 {
		t.Errorf("expected txn priority 11; got %d", reply.Txn.Priority)
	}
}

func TestKeyAddress(t *testing.T) {
	defer leaktest.AfterTest(t)()
	testCases := []struct {
		key roachpb.Key
	}{
		{MakeNameMetadataKey(0, "BAR")},
		{MakeNameMetadataKey(1, "BAR")},
		{MakeNameMetadataKey(1, "foo")},
		{MakeNameMetadataKey(2, "foo")},
		{MakeDescMetadataKey(123)},
		{MakeDescMetadataKey(124)},
	}
	var lastKey roachpb.Key
	for i, test := range testCases {
		resultAddr, err := keys.Addr(test.key)
		if err != nil {
			t.Fatal(err)
		}
		result := resultAddr.AsRawKey()
		if result.Compare(lastKey) <= 0 {
			t.Errorf("%d: key address %q is <= %q", i, result, lastKey)
		}
		lastKey = result
	}
}

// Test that we can resolve the qnames in an expression that has already been
// resolved.
func TestRetryResolveQNames(t *testing.T) {
	defer leaktest.AfterTest(t)()

	expr, err := parser.ParseExprTraditional(`COUNT(a)`)
	if err != nil {
		t.Fatal(err)
	}

	for i := 0; i < 2; i++ {
		desc := testTableDesc()
		s := testInitDummySelectNode(desc)
		if err := desc.AllocateIDs(); err != nil {
			t.Fatal(err)
		}

		_, err := s.resolveQNames(expr)
		if err != nil {
			t.Fatal(err)
		}
		if len(s.qvals) != 1 {
			t.Fatalf("%d: expected 1 qvalue, but found %d", i, len(s.qvals))
		}
		if _, ok := s.qvals[columnRef{&s.source.info, 0}]; !ok {
			t.Fatalf("%d: unable to find qvalue for column 0 (a)", i)
		}
	}
}

// TestInfoStoreMostDistant verifies selection of most distant node &
// associated hops.
func TestInfoStoreMostDistant(t *testing.T) {
	defer leaktest.AfterTest(t)()
	nodes := []roachpb.NodeID{
		roachpb.NodeID(1),
		roachpb.NodeID(2),
		roachpb.NodeID(3),
	}
	stopper := stop.NewStopper()
	defer stopper.Stop()
	is := newInfoStore(context.TODO(), 1, emptyAddr, stopper)
	// Add info from each address, with hop count equal to index+1.
	for i := 0; i < len(nodes); i++ {
		inf := is.newInfo(nil, time.Second)
		inf.Hops = uint32(i + 1)
		inf.NodeID = nodes[i]
		if err := is.addInfo(fmt.Sprintf("b.%d", i), inf); err != nil {
			t.Fatal(err)
		}
		nodeID, hops := is.mostDistant()
		if nodeID != inf.NodeID {
			t.Errorf("%d: expected node %d; got %d", i, inf.NodeID, nodeID)
		}
		if hops != inf.Hops {
			t.Errorf("%d: expected node %d; got %d", i, inf.Hops, hops)
		}
	}
}

// TestRangeLookupOptionOnReverseScan verifies that a lookup triggered by a
// ReverseScan request has the useReverseScan specified.
func TestRangeLookupOptionOnReverseScan(t *testing.T) {
	defer leaktest.AfterTest(t)
	g, s := makeTestGossip(t)
	defer s()

	var testFn rpcSendFn = func(_ rpc.Options, method string, addrs []net.Addr, getArgs func(addr net.Addr) proto.Message, _ func() proto.Message, _ *rpc.Context) ([]proto.Message, error) {
		return []proto.Message{getArgs(nil).(*roachpb.BatchRequest).CreateReply()}, nil
	}

	ctx := &DistSenderContext{
		RPCSend: testFn,
		RangeDescriptorDB: mockRangeDescriptorDB(func(k roachpb.RKey, considerIntents, useReverseScan bool) ([]roachpb.RangeDescriptor, *roachpb.Error) {
			if len(k) > 0 && !useReverseScan {
				t.Fatalf("expected UseReverseScan to be set")
			}
			return []roachpb.RangeDescriptor{testRangeDescriptor}, nil
		}),
	}
	ds := NewDistSender(ctx, g)
	rScan := &roachpb.ReverseScanRequest{
		Span: roachpb.Span{Key: roachpb.Key("a"), EndKey: roachpb.Key("b")},
	}
	if _, err := client.SendWrapped(ds, nil, rScan); err != nil {
		t.Fatal(err)
	}
}

// TestRejectFutureCommand verifies that lease holders reject commands that
// would cause a large time jump.
func TestRejectFutureCommand(t *testing.T) {
	defer leaktest.AfterTest(t)()

	const maxOffset = 100 * time.Millisecond
	manual := hlc.NewManualClock(0)
	clock := hlc.NewClock(manual.UnixNano)
	clock.SetMaxOffset(maxOffset)
	mtc := multiTestContext{
		clock: clock,
	}
	mtc.Start(t, 1)
	defer mtc.Stop()

	// First do a write. The first write will advance the clock by MaxOffset
	// because of the read cache's low water mark.
	getArgs := putArgs([]byte("b"), []byte("b"))
	if _, err := client.SendWrapped(rg1(mtc.stores[0]), nil, &getArgs); err != nil {
		t.Fatal(err)
	}
	if now := clock.Now(); now.WallTime != int64(maxOffset) {
		t.Fatalf("expected clock to advance to 100ms; got %s", now)
	}
	// The logical clock has advanced past the physical clock; increment
	// the "physical" clock to catch up.
	manual.Increment(int64(maxOffset))

	startTime := manual.UnixNano()

	// Commands with a future timestamp that is within the MaxOffset
	// bound will be accepted and will cause the clock to advance.
	for i := int64(0); i < 3; i++ {
		incArgs := incrementArgs([]byte("a"), 5)
		ts := hlc.ZeroTimestamp.Add(startTime+((i+1)*30)*int64(time.Millisecond), 0)
		if _, err := client.SendWrappedWith(rg1(mtc.stores[0]), nil, roachpb.Header{Timestamp: ts}, &incArgs); err != nil {
			t.Fatal(err)
		}
	}
	if now := clock.Now(); now.WallTime != int64(190*time.Millisecond) {
		t.Fatalf("expected clock to advance to 190ms; got %s", now)
	}

	// Once the accumulated offset reaches MaxOffset, commands will be rejected.
	incArgs := incrementArgs([]byte("a"), 11)
	ts := hlc.ZeroTimestamp.Add(int64((time.Duration(startTime)+maxOffset+1)*time.Millisecond), 0)
	if _, err := client.SendWrappedWith(rg1(mtc.stores[0]), nil, roachpb.Header{Timestamp: ts}, &incArgs); err == nil {
		t.Fatalf("expected clock offset error but got nil")
	}

	// The clock remained at 190ms and the final command was not executed.
	if now := clock.Now(); now.WallTime != int64(190*time.Millisecond) {
		t.Errorf("expected clock to advance to 190ms; got %s", now)
	}
	val, _, err := engine.MVCCGet(context.Background(), mtc.engines[0], roachpb.Key("a"), clock.Now(), true, nil)
	if err != nil {
		t.Fatal(err)
	}
	if v := mustGetInt(val); v != 15 {
		t.Errorf("expected 15, got %v", v)
	}
}

// TestStoreRangeUpReplicate verifies that the replication queue will notice
// under-replicated ranges and replicate them.
func TestStoreRangeUpReplicate(t *testing.T) {
	defer leaktest.AfterTest(t)
	mtc := startMultiTestContext(t, 3)
	defer mtc.Stop()

	// Initialize the gossip network.
	var wg sync.WaitGroup
	wg.Add(len(mtc.stores))
	key := gossip.MakePrefixPattern(gossip.KeyStorePrefix)
	mtc.stores[0].Gossip().RegisterCallback(key, func(_ string, _ roachpb.Value) { wg.Done() })
	for _, s := range mtc.stores {
		s.GossipStore()
	}
	wg.Wait()

	// Once we know our peers, trigger a scan.
	mtc.stores[0].ForceReplicationScanAndProcess()

	// The range should become available on every node.
	if err := util.IsTrueWithin(func() bool {
		for _, s := range mtc.stores {
			r := s.LookupReplica(roachpb.RKey("a"), roachpb.RKey("b"))
			if r == nil {
				return false
			}
		}
		return true
	}, replicationTimeout); err != nil {
		t.Fatal(err)
	}
}

// TestBuildEndpointListRemoveStagnantClocks tests the side effect of removing
// older offsets when we build an endpoint list.
func TestBuildEndpointListRemoveStagnantClocks(t *testing.T) {
	defer leaktest.AfterTest(t)()
	offsets := map[string]RemoteOffset{
		"0":         {Offset: 0, Uncertainty: 10, MeasuredAt: 11},
		"stagnant0": {Offset: 1, Uncertainty: 10, MeasuredAt: 0},
		"1":         {Offset: 2, Uncertainty: 10, MeasuredAt: 20},
		"stagnant1": {Offset: 3, Uncertainty: 10, MeasuredAt: 9},
	}

	manual := hlc.NewManualClock(0)
	clock := hlc.NewClock(manual.UnixNano)
	clock.SetMaxOffset(5 * time.Nanosecond)
	remoteClocks := newRemoteClockMonitor(clock)
	// The stagnant offsets older than this will be removed.
	remoteClocks.monitorInterval = 10 * time.Nanosecond
	remoteClocks.mu.offsets = offsets
	remoteClocks.mu.lastMonitoredAt = time.Unix(0, 10) // offsets measured before this will be removed.

	remoteClocks.buildEndpointList()

	_, ok0 := offsets["stagnant0"]
	_, ok1 := offsets["stagnant1"]

	if ok0 || ok1 {
		t.Errorf("expected stagant offsets removed, instead offsets: %v", offsets)
	}
}

// TestFindOffsetWithLargeError tests a case where offset errors are
// bigger than the max offset (e.g., a case where heartbeat messages
// to the node are having high latency).
func TestFindOffsetWithLargeError(t *testing.T) {
	defer leaktest.AfterTest(t)()
	maxOffset := 100 * time.Nanosecond

	manual := hlc.NewManualClock(0)
	clock := hlc.NewClock(manual.UnixNano)
	clock.SetMaxOffset(maxOffset)
	offsets := map[string]RemoteOffset{}
	// Offsets are bigger than maxOffset, but Errors are also bigger than Offset.
	offsets["0"] = RemoteOffset{Offset: 110, Uncertainty: 300}
	offsets["1"] = RemoteOffset{Offset: 120, Uncertainty: 300}
	offsets["2"] = RemoteOffset{Offset: 130, Uncertainty: 300}

	remoteClocks := newRemoteClockMonitor(clock)
	remoteClocks.mu.offsets = offsets

	interval, err := remoteClocks.findOffsetInterval()
	if err != nil {
		t.Fatal(err)
	}
	expectedInterval := clusterOffsetInterval{lowerbound: -270, upperbound: 510}
	if interval != expectedInterval {
		t.Errorf("expected interval %v, instead %v", expectedInterval, interval)
	}
	// The interval is still considered healthy.
	assertIntervalHealth(true, interval, maxOffset, t)
}

func TestExactPrefix(t *testing.T) {
	defer leaktest.AfterTest(t)

	testData := []struct {
		expr     string
		columns  []string
		expected int
	}{
		{`a = 1`, []string{"a"}, 1},
		{`a != 1`, []string{"a"}, 0},
		{`a IN (1)`, []string{"a"}, 1},
		{`a = 1 AND b = 1`, []string{"a", "b"}, 2},
		{`(a, b) IN ((1, 2))`, []string{"a", "b"}, 2},
		{`(a, b) IN ((1, 2))`, []string{"a"}, 1},
		{`(a, b) IN ((1, 2))`, []string{"b"}, 1},
		{`(a, b) IN ((1, 2)) AND c = true`, []string{"a", "b", "c"}, 3},
		{`a = 1 AND (b, c) IN ((2, true))`, []string{"a", "b", "c"}, 3},
	}
	for _, d := range testData {
		desc, index := makeTestIndex(t, d.columns)
		constraints := makeConstraints(t, d.expr, desc, index)
		prefix := exactPrefix(constraints)
		if d.expected != prefix {
			t.Errorf("%s: expected %d, but found %d", d.expr, d.expected, prefix)
		}
	}
}

func TestColumnTypeSQLString(t *testing.T) {
	defer leaktest.AfterTest(t)

	testData := []struct {
		colType     sql.ColumnType
		expectedSQL string
	}{
		{sql.ColumnType{Kind: sql.ColumnType_INT}, "INT"},
		{sql.ColumnType{Kind: sql.ColumnType_INT, Width: 2}, "INT(2)"},
		{sql.ColumnType{Kind: sql.ColumnType_FLOAT}, "FLOAT"},
		{sql.ColumnType{Kind: sql.ColumnType_FLOAT, Precision: 3}, "FLOAT(3)"},
		{sql.ColumnType{Kind: sql.ColumnType_DECIMAL}, "DECIMAL"},
		{sql.ColumnType{Kind: sql.ColumnType_DECIMAL, Precision: 6}, "DECIMAL(6)"},
		{sql.ColumnType{Kind: sql.ColumnType_DECIMAL, Precision: 7, Width: 8}, "DECIMAL(7,8)"},
		{sql.ColumnType{Kind: sql.ColumnType_DATE}, "DATE"},
		{sql.ColumnType{Kind: sql.ColumnType_TIMESTAMP}, "TIMESTAMP"},
		{sql.ColumnType{Kind: sql.ColumnType_INTERVAL}, "INTERVAL"},
		{sql.ColumnType{Kind: sql.ColumnType_STRING}, "STRING"},
		{sql.ColumnType{Kind: sql.ColumnType_STRING, Width: 10}, "STRING(10)"},
		{sql.ColumnType{Kind: sql.ColumnType_BYTES}, "BYTES"},
	}
	for i, d := range testData {
		sql := d.colType.SQLString()
		if d.expectedSQL != sql {
			t.Errorf("%d: expected %s, but got %s", i, d.expectedSQL, sql)
		}
	}
}

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

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

	txn := newTxn(s.Clock, proto.Key("a"))
	call := proto.Call{
		Args:  createPutRequest(proto.Key("a"), []byte("value"), txn),
		Reply: &proto.PutResponse{},
	}
	if err := sendCall(s.Sender, call); err != nil {
		t.Fatal(err)
	}

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

	if err := util.IsTrueWithin(func() bool {
		// Locking the TxnCoordSender to prevent a data race.
		s.Sender.Lock()
		_, ok := s.Sender.txns[string(txn.ID)]
		s.Sender.Unlock()
		return !ok
	}, 50*time.Millisecond); err != nil {
		t.Error("expected garbage collection")
	}
}

// TestTxnCoordSenderEndTxn verifies that ending a transaction
// sends resolve write intent requests and removes the transaction
// from the txns map.
func TestTxnCoordSenderEndTxn(t *testing.T) {
	defer leaktest.AfterTest(t)
	s := createTestDB(t)
	defer s.Stop()

	txn := newTxn(s.Clock, proto.Key("a"))
	pReply := &proto.PutResponse{}
	key := proto.Key("a")
	call := proto.Call{
		Args:  createPutRequest(key, []byte("value"), txn),
		Reply: pReply,
	}
	if err := sendCall(s.Sender, call); err != nil {
		t.Fatal(err)
	}
	if pReply.GoError() != nil {
		t.Fatal(pReply.GoError())
	}
	etReply := &proto.EndTransactionResponse{}
	s.Sender.Send(context.Background(), proto.Call{
		Args: &proto.EndTransactionRequest{
			RequestHeader: proto.RequestHeader{
				Key:       txn.Key,
				Timestamp: txn.Timestamp,
				Txn:       txn,
			},
			Commit: true,
		},
		Reply: etReply,
	})
	if etReply.Error != nil {
		t.Fatal(etReply.GoError())
	}
	verifyCleanup(key, s.Sender, s.Eng, t)
}

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

	txn1 := newTxn(s.Clock, proto.Key("a"))
	txn2 := newTxn(s.Clock, proto.Key("b"))
	call := proto.Call{
		Args:  createPutRequest(proto.Key("a"), []byte("value"), txn1),
		Reply: &proto.PutResponse{}}
	if err := sendCall(s.Sender, call); err != nil {
		t.Fatal(err)
	}
	call = proto.Call{
		Args:  createPutRequest(proto.Key("b"), []byte("value"), txn2),
		Reply: &proto.PutResponse{}}
	if err := sendCall(s.Sender, call); err != nil {
		t.Fatal(err)
	}

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

func TestBatchDefer(t *testing.T) {
	defer leaktest.AfterTest(t)

	stopper := stop.NewStopper()
	defer stopper.Stop()
	e := NewInMem(roachpb.Attributes{}, 1<<20, stopper)

	b := e.NewBatch()
	defer b.Close()

	list := []string{}

	b.Defer(func() {
		list = append(list, "one")
	})
	b.Defer(func() {
		list = append(list, "two")
	})

	if err := b.Commit(); err != nil {
		t.Fatal(err)
	}

	// Order was reversed when the defers were run.
	if !reflect.DeepEqual(list, []string{"two", "one"}) {
		t.Errorf("expected [two, one]; got %v", list)
	}
}

// TestIsHealthyOffsetInterval tests if we correctly determine if
// a clusterOffsetInterval is healthy or not i.e. if it indicates that the
// local clock has too great an offset or not.
func TestIsHealthyOffsetInterval(t *testing.T) {
	defer leaktest.AfterTest(t)()
	maxOffset := 10 * time.Nanosecond

	interval := clusterOffsetInterval{
		lowerbound: 0,
		upperbound: 0,
	}
	assertIntervalHealth(true, interval, maxOffset, t)

	interval = clusterOffsetInterval{
		lowerbound: -11,
		upperbound: 11,
	}
	assertIntervalHealth(true, interval, maxOffset, t)

	interval = clusterOffsetInterval{
		lowerbound: -20,
		upperbound: -11,
	}
	assertIntervalHealth(false, interval, maxOffset, t)

	interval = clusterOffsetInterval{
		lowerbound: 11,
		upperbound: 20,
	}
	assertIntervalHealth(false, interval, maxOffset, t)

	interval = clusterOffsetInterval{
		lowerbound: math.MaxInt64,
		upperbound: math.MaxInt64,
	}
	assertIntervalHealth(false, interval, maxOffset, t)
}

// TestHeartbeatResponseFanout check 2 raft groups on the same node distribution,
// but each group has different Term, heartbeat response from each group should
// not disturb other group's Term or Leadership
func TestHeartbeatResponseFanout(t *testing.T) {
	defer leaktest.AfterTest(t)
	stopper := stop.NewStopper()
	defer stopper.Stop()

	cluster := newTestCluster(nil, 3, stopper, t)
	groupID1 := roachpb.RangeID(1)
	cluster.createGroup(groupID1, 0, 3 /* replicas */)

	groupID2 := roachpb.RangeID(2)
	cluster.createGroup(groupID2, 0, 3 /* replicas */)

	leaderIndex := 0

	cluster.elect(leaderIndex, groupID1)
	// GroupID2 will have 3 round of election, so it will have different
	// term with groupID1, but both leader on the same node.
	for i := 2; i >= 0; i-- {
		leaderIndex = i
		cluster.elect(leaderIndex, groupID2)
	}
	// Send a coalesced heartbeat.
	// Heartbeat response from groupID2 will have a big term than which from groupID1.
	cluster.nodes[0].coalescedHeartbeat()
	// Start submit a command to see if groupID1's leader changed?
	cluster.nodes[0].SubmitCommand(groupID1, makeCommandID(), []byte("command"))

	select {
	case _ = <-cluster.events[0].CommandCommitted:
		log.Infof("SubmitCommand succeed after Heartbeat Response fanout")
	case <-time.After(500 * time.Millisecond):
		t.Fatalf("No leader after Heartbeat Response fanout")
	}
}

// TestEndpointListSort tests the sort interface for endpointLists.
func TestEndpointListSort(t *testing.T) {
	defer leaktest.AfterTest(t)()
	list := endpointList{
		endpoint{offset: 5, endType: +1},
		endpoint{offset: 3, endType: -1},
		endpoint{offset: 3, endType: +1},
		endpoint{offset: 1, endType: -1},
		endpoint{offset: 4, endType: +1},
	}

	sortedList := endpointList{
		endpoint{offset: 1, endType: -1},
		endpoint{offset: 3, endType: -1},
		endpoint{offset: 3, endType: +1},
		endpoint{offset: 4, endType: +1},
		endpoint{offset: 5, endType: +1},
	}

	sort.Sort(list)
	for i := range sortedList {
		if list[i] != sortedList[i] {
			t.Errorf("expected index %d of sorted list to be %v, instead %v",
				i, sortedList[i], list[i])
		}
	}

	if len(list) != len(sortedList) {
		t.Errorf("exptected endpoint list to be size %d, instead %d",
			len(sortedList), len(list))
	}
}

// TestLeaderRemoveSelf verifies that a leader can remove itself
// without panicking and future access to the range returns a
// RangeNotFoundError (not RaftGroupDeletedError, and even before
// the ReplicaGCQueue has run).
func TestLeaderRemoveSelf(t *testing.T) {
	defer leaktest.AfterTest(t)

	mtc := startMultiTestContext(t, 2)
	defer mtc.Stop()
	// Disable the replica GC queue. This verifies that the replica is
	// considered removed even before the gc queue has run, and also
	// helps avoid a deadlock at shutdown.
	mtc.stores[0].DisableReplicaGCQueue(true)
	raftID := roachpb.RangeID(1)
	mtc.replicateRange(raftID, 1)
	// Remove the replica from first store.
	mtc.unreplicateRange(raftID, 0)
	getArgs := getArgs([]byte("a"))

	// Force the read command request a new lease.
	clock := mtc.clocks[0]
	header := roachpb.Header{}
	header.Timestamp = clock.Update(clock.Now().Add(int64(storage.DefaultLeaderLeaseDuration), 0))

	// Expect get a RangeNotFoundError.
	_, pErr := client.SendWrappedWith(rg1(mtc.stores[0]), nil, header, &getArgs)
	if _, ok := pErr.GoError().(*roachpb.RangeNotFoundError); !ok {
		t.Fatalf("expect get RangeNotFoundError, actual get %v ", pErr)
	}
}

func TestPGWireMetrics(t *testing.T) {
	defer leaktest.AfterTest(t)

	s := server.StartTestServer(t)
	defer s.Stop()

	// Setup pgwire client.
	pgUrl, cleanupFn := sqlutils.PGUrl(t, s, security.RootUser, "TestPGWireMetrics")
	defer cleanupFn()

	const minbytes = 20

	// Make sure we're starting at 0.
	if _, _, err := checkPGWireMetrics(s, 0, 0, 0, 0); err != nil {
		t.Fatal(err)
	}

	// A single query should give us some I/O.
	if err := trivialQuery(pgUrl); err != nil {
		t.Fatal(err)
	}
	bytesIn, bytesOut, err := checkPGWireMetrics(s, minbytes, minbytes, 300, 300)
	if err != nil {
		t.Fatal(err)
	}
	if err := trivialQuery(pgUrl); err != nil {
		t.Fatal(err)
	}

	// A second query should give us more I/O.
	_, _, err = checkPGWireMetrics(s, bytesIn+minbytes, bytesOut+minbytes, 300, 300)
	if err != nil {
		t.Fatal(err)
	}
}