Golang parser.NewDInt函數代碼示例

func checkEquivExpr(a, b parser.TypedExpr, qvals qvalMap) error {
	// The expressions above only use the values 1 and 2. Verify that the
	// simplified expressions evaluate to the same value as the original
	// expression for interesting values.
	for _, v := range []parser.Datum{
		parser.NewDInt(0),
		parser.NewDInt(1),
		parser.NewDInt(2),
		parser.NewDInt(3),
		parser.DNull,
	} {
		for _, q := range qvals {
			q.datum = v
		}
		da, err := a.Eval(parser.EvalContext{})
		if err != nil {
			return fmt.Errorf("%s: %v", a, err)
		}
		db, err := b.Eval(parser.EvalContext{})
		if err != nil {
			return fmt.Errorf("%s: %v", b, err)
		}
		// This is tricky: we don't require the expressions to produce identical
		// results, but to either both return true or both return not true (either
		// false or NULL).
		if (da == parser.DBoolTrue) != (db == parser.DBoolTrue) {
			return fmt.Errorf("%s: %s: expected %s, but found %s", a, v, da, db)
		}
	}
	return nil
}

// golangFillQueryArguments populates the placeholder map with
// types and values from an array of Go values.
// TODO: This does not support arguments of the SQL 'Date' type, as there is not
// an equivalent type in Go's standard library. It's not currently needed by any
// of our internal tables.
func golangFillQueryArguments(pinfo *parser.PlaceholderInfo, args []interface{}) {
	pinfo.Clear()

	for i, arg := range args {
		k := fmt.Sprint(i + 1)
		if arg == nil {
			pinfo.SetValue(k, parser.DNull)
			continue
		}

		// A type switch to handle a few explicit types with special semantics:
		// - Datums are passed along as is.
		// - Time datatypes get special representation in the database.
		var d parser.Datum
		switch t := arg.(type) {
		case parser.Datum:
			d = t
		case time.Time:
			d = parser.MakeDTimestamp(t, time.Microsecond)
		case time.Duration:
			d = &parser.DInterval{Duration: duration.Duration{Nanos: t.Nanoseconds()}}
		case *inf.Dec:
			dd := &parser.DDecimal{}
			dd.Set(t)
			d = dd
		}
		if d == nil {
			// Handle all types which have an underlying type that can be stored in the
			// database.
			// Note: if this reflection becomes a performance concern in the future,
			// commonly used types could be added explicitly into the type switch above
			// for a performance gain.
			val := reflect.ValueOf(arg)
			switch val.Kind() {
			case reflect.Bool:
				d = parser.MakeDBool(parser.DBool(val.Bool()))
			case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
				d = parser.NewDInt(parser.DInt(val.Int()))
			case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
				d = parser.NewDInt(parser.DInt(val.Uint()))
			case reflect.Float32, reflect.Float64:
				d = parser.NewDFloat(parser.DFloat(val.Float()))
			case reflect.String:
				d = parser.NewDString(val.String())
			case reflect.Slice:
				// Handle byte slices.
				if val.Type().Elem().Kind() == reflect.Uint8 {
					d = parser.NewDBytes(parser.DBytes(val.Bytes()))
				}
			}
			if d == nil {
				panic(fmt.Sprintf("unexpected type %T", arg))
			}
		}
		pinfo.SetValue(k, d)
	}
}

// Arg implements the parser.Args interface.
// TODO: This does not support arguments of the SQL 'Date' type, as there is not
// an equivalent type in Go's standard library. It's not currently needed by any
// of our internal tables.
func (gp golangParameters) Arg(name string) (parser.Datum, bool) {
	i, err := processPositionalArgument(name)
	if err != nil {
		return nil, false
	}
	if i < 1 || int(i) > len(gp) {
		return nil, false
	}
	arg := gp[i-1]
	if arg == nil {
		return parser.DNull, true
	}

	// A type switch to handle a few explicit types with special semantics.
	switch t := arg.(type) {
	// Datums are passed along as is.
	case parser.Datum:
		return t, true
	// Time datatypes get special representation in the database.
	case time.Time:
		return parser.MakeDTimestamp(t, time.Microsecond), true
	case time.Duration:
		return &parser.DInterval{Duration: duration.Duration{Nanos: t.Nanoseconds()}}, true
	case *inf.Dec:
		dd := &parser.DDecimal{}
		dd.Set(t)
		return dd, true
	}

	// Handle all types which have an underlying type that can be stored in the
	// database.
	// Note: if this reflection becomes a performance concern in the future,
	// commonly used types could be added explicitly into the type switch above
	// for a performance gain.
	val := reflect.ValueOf(arg)
	switch val.Kind() {
	case reflect.Bool:
		return parser.MakeDBool(parser.DBool(val.Bool())), true
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return parser.NewDInt(parser.DInt(val.Int())), true
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		return parser.NewDInt(parser.DInt(val.Uint())), true
	case reflect.Float32, reflect.Float64:
		return parser.NewDFloat(parser.DFloat(val.Float())), true
	case reflect.String:
		return parser.NewDString(val.String()), true
	case reflect.Slice:
		// Handle byte slices.
		if val.Type().Elem().Kind() == reflect.Uint8 {
			return parser.NewDBytes(parser.DBytes(val.Bytes())), true
		}
	}

	panic(fmt.Sprintf("unexpected type %T", arg))
}

// Events is an endpoint that returns the latest event log entries, with the following
// optional URL parameters:
//
// type=STRING  returns events with this type (e.g. "create_table")
// targetID=INT returns events for that have this targetID
func (s *adminServer) Events(ctx context.Context, req *serverpb.EventsRequest) (*serverpb.EventsResponse, error) {
	args := sql.SessionArgs{User: s.getUser(req)}
	session := sql.NewSession(ctx, args, s.server.sqlExecutor, nil)

	// Execute the query.
	q := makeSQLQuery()
	q.Append("SELECT timestamp, eventType, targetID, reportingID, info, uniqueID ")
	q.Append("FROM system.eventlog ")
	q.Append("WHERE true ") // This simplifies the WHERE clause logic below.
	if len(req.Type) > 0 {
		q.Append("AND eventType = $ ", parser.NewDString(req.Type))
	}
	if req.TargetId > 0 {
		q.Append("AND targetID = $ ", parser.NewDInt(parser.DInt(req.TargetId)))
	}
	q.Append("ORDER BY timestamp DESC ")
	q.Append("LIMIT $", parser.NewDInt(parser.DInt(apiEventLimit)))
	if len(q.Errors()) > 0 {
		return nil, s.serverErrors(q.Errors())
	}
	r := s.server.sqlExecutor.ExecuteStatements(session, q.String(), q.QueryArguments())
	if err := s.checkQueryResults(r.ResultList, 1); err != nil {
		return nil, s.serverError(err)
	}

	// Marshal response.
	var resp serverpb.EventsResponse
	scanner := makeResultScanner(r.ResultList[0].Columns)
	for _, row := range r.ResultList[0].Rows {
		var event serverpb.EventsResponse_Event
		var ts time.Time
		if err := scanner.ScanIndex(row, 0, &ts); err != nil {
			return nil, err
		}
		event.Timestamp = serverpb.EventsResponse_Event_Timestamp{Sec: ts.Unix(), Nsec: uint32(ts.Nanosecond())}
		if err := scanner.ScanIndex(row, 1, &event.EventType); err != nil {
			return nil, err
		}
		if err := scanner.ScanIndex(row, 2, &event.TargetID); err != nil {
			return nil, err
		}
		if err := scanner.ScanIndex(row, 3, &event.ReportingID); err != nil {
			return nil, err
		}
		if err := scanner.ScanIndex(row, 4, &event.Info); err != nil {
			return nil, err
		}
		if err := scanner.ScanIndex(row, 5, &event.UniqueID); err != nil {
			return nil, err
		}

		resp.Events = append(resp.Events, event)
	}
	return &resp, nil
}

// queryNamespaceID queries for the ID of the namespace with the given name and
// parent ID.
func (s *adminServer) queryNamespaceID(
	session *sql.Session, parentID sqlbase.ID, name string,
) (sqlbase.ID, error) {
	const query = `SELECT id FROM system.namespace WHERE parentID = $1 AND name = $2`
	params := parser.NewPlaceholderInfo()
	params.SetValue(`1`, parser.NewDInt(parser.DInt(parentID)))
	params.SetValue(`2`, parser.NewDString(name))
	r := s.server.sqlExecutor.ExecuteStatements(session, query, params)
	if err := s.checkQueryResults(r.ResultList, 1); err != nil {
		return 0, err
	}

	result := r.ResultList[0]
	if len(result.Rows) == 0 {
		return 0, errors.Errorf("namespace %s with ParentID %d not found", name, parentID)
	}

	var id int64
	scanner := resultScanner{}
	err := scanner.ScanIndex(result.Rows[0], 0, &id)
	if err != nil {
		return 0, err
	}

	return sqlbase.ID(id), nil
}

// queryZone retrieves the specific ZoneConfig associated with the supplied ID,
// if it exists.
func (s *adminServer) queryZone(
	session *sql.Session, id sqlbase.ID,
) (config.ZoneConfig, bool, error) {
	const query = `SELECT config FROM system.zones WHERE id = $1`
	params := parser.NewPlaceholderInfo()
	params.SetValue(`1`, parser.NewDInt(parser.DInt(id)))
	r := s.server.sqlExecutor.ExecuteStatements(session, query, params)
	if err := s.checkQueryResults(r.ResultList, 1); err != nil {
		return config.ZoneConfig{}, false, err
	}

	result := r.ResultList[0]
	if len(result.Rows) == 0 {
		return config.ZoneConfig{}, false, nil
	}

	var zoneBytes []byte
	scanner := resultScanner{}
	err := scanner.ScanIndex(result.Rows[0], 0, &zoneBytes)
	if err != nil {
		return config.ZoneConfig{}, false, err
	}

	var zone config.ZoneConfig
	if err := zone.Unmarshal(zoneBytes); err != nil {
		return config.ZoneConfig{}, false, err
	}
	return zone, true, nil
}

func makeIntTestDatum(count int) []parser.Datum {
	rng, _ := randutil.NewPseudoRand()

	vals := make([]parser.Datum, count)
	for i := range vals {
		vals[i] = parser.NewDInt(parser.DInt(rng.Int63()))
	}
	return vals
}

// ShowIndex returns all the indexes for a table.
// Privileges: Any privilege on table.
//   Notes: postgres does not have a SHOW INDEXES statement.
//          mysql requires some privilege for any column.
func (p *planner) ShowIndex(n *parser.ShowIndex) (planNode, error) {
	tn, err := n.Table.NormalizeWithDatabaseName(p.session.Database)
	if err != nil {
		return nil, err
	}

	desc, err := p.mustGetTableDesc(tn)
	if err != nil {
		return nil, err
	}
	if err := p.anyPrivilege(desc); err != nil {
		return nil, err
	}

	v := &valuesNode{
		columns: []ResultColumn{
			{Name: "Table", Typ: parser.TypeString},
			{Name: "Name", Typ: parser.TypeString},
			{Name: "Unique", Typ: parser.TypeBool},
			{Name: "Seq", Typ: parser.TypeInt},
			{Name: "Column", Typ: parser.TypeString},
			{Name: "Direction", Typ: parser.TypeString},
			{Name: "Storing", Typ: parser.TypeBool},
		},
	}

	appendRow := func(index sqlbase.IndexDescriptor, colName string, sequence int,
		direction string, isStored bool) {
		v.rows = append(v.rows, []parser.Datum{
			parser.NewDString(tn.Table()),
			parser.NewDString(index.Name),
			parser.MakeDBool(parser.DBool(index.Unique)),
			parser.NewDInt(parser.DInt(sequence)),
			parser.NewDString(colName),
			parser.NewDString(direction),
			parser.MakeDBool(parser.DBool(isStored)),
		})
	}

	for _, index := range append([]sqlbase.IndexDescriptor{desc.PrimaryIndex}, desc.Indexes...) {
		sequence := 1
		for i, col := range index.ColumnNames {
			appendRow(index, col, sequence, index.ColumnDirections[i].String(), false)
			sequence++
		}
		for _, col := range index.StoreColumnNames {
			appendRow(index, col, sequence, "N/A", true)
			sequence++
		}
	}
	return v, nil
}

// RandDatum generates a random Datum of the given type.
// If null is true, the datum can be DNull.
func RandDatum(rng *rand.Rand, typ ColumnType_Kind, null bool) parser.Datum {
	if null && rng.Intn(10) == 0 {
		return parser.DNull
	}
	switch typ {
	case ColumnType_BOOL:
		return parser.MakeDBool(rng.Intn(2) == 1)
	case ColumnType_INT:
		return parser.NewDInt(parser.DInt(rng.Int63()))
	case ColumnType_FLOAT:
		return parser.NewDFloat(parser.DFloat(rng.NormFloat64()))
	case ColumnType_DECIMAL:
		d := &parser.DDecimal{}
		d.Dec.SetScale(inf.Scale(rng.Intn(40) - 20))
		d.Dec.SetUnscaled(rng.Int63())
		return d
	case ColumnType_DATE:
		return parser.NewDDate(parser.DDate(rng.Intn(10000)))
	case ColumnType_TIMESTAMP:
		return &parser.DTimestamp{Time: time.Unix(rng.Int63n(1000000), rng.Int63n(1000000))}
	case ColumnType_INTERVAL:
		return &parser.DInterval{Duration: duration.Duration{Months: rng.Int63n(1000),
			Days:  rng.Int63n(1000),
			Nanos: rng.Int63n(1000000),
		}}
	case ColumnType_STRING:
		// Generate a random ASCII string.
		p := make([]byte, rng.Intn(10))
		for i := range p {
			p[i] = byte(1 + rng.Intn(127))
		}
		return parser.NewDString(string(p))
	case ColumnType_BYTES:
		p := make([]byte, rng.Intn(10))
		_, _ = rng.Read(p)
		return parser.NewDBytes(parser.DBytes(p))
	case ColumnType_TIMESTAMPTZ:
		return &parser.DTimestampTZ{Time: time.Unix(rng.Int63n(1000000), rng.Int63n(1000000))}
	default:
		panic(fmt.Sprintf("invalid type %s", typ))
	}
}

// decodeOidDatum decodes bytes with specified Oid and format code into
// a datum.
func decodeOidDatum(id oid.Oid, code formatCode, b []byte) (parser.Datum, error) {
	var d parser.Datum
	switch id {
	case oid.T_bool:
		switch code {
		case formatText:
			v, err := strconv.ParseBool(string(b))
			if err != nil {
				return d, err
			}
			d = parser.MakeDBool(parser.DBool(v))
		default:
			return d, fmt.Errorf("unsupported bool format code: %d", code)
		}
	case oid.T_int2:
		switch code {
		case formatText:
			i, err := strconv.ParseInt(string(b), 10, 64)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		case formatBinary:
			var i int16
			err := binary.Read(bytes.NewReader(b), binary.BigEndian, &i)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		default:
			return d, fmt.Errorf("unsupported int2 format code: %d", code)
		}
	case oid.T_int4:
		switch code {
		case formatText:
			i, err := strconv.ParseInt(string(b), 10, 64)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		case formatBinary:
			var i int32
			err := binary.Read(bytes.NewReader(b), binary.BigEndian, &i)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		default:
			return d, fmt.Errorf("unsupported int4 format code: %d", code)
		}
	case oid.T_int8:
		switch code {
		case formatText:
			i, err := strconv.ParseInt(string(b), 10, 64)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		case formatBinary:
			var i int64
			err := binary.Read(bytes.NewReader(b), binary.BigEndian, &i)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		default:
			return d, fmt.Errorf("unsupported int8 format code: %d", code)
		}
	case oid.T_float4:
		switch code {
		case formatText:
			f, err := strconv.ParseFloat(string(b), 64)
			if err != nil {
				return d, err
			}
			d = parser.NewDFloat(parser.DFloat(f))
		case formatBinary:
			var f float32
			err := binary.Read(bytes.NewReader(b), binary.BigEndian, &f)
			if err != nil {
				return d, err
			}
			d = parser.NewDFloat(parser.DFloat(f))
		default:
			return d, fmt.Errorf("unsupported float4 format code: %d", code)
		}
	case oid.T_float8:
		switch code {
		case formatText:
			f, err := strconv.ParseFloat(string(b), 64)
			if err != nil {
				return d, err
			}
			d = parser.NewDFloat(parser.DFloat(f))
		case formatBinary:
			var f float64
			err := binary.Read(bytes.NewReader(b), binary.BigEndian, &f)
			if err != nil {
//.........這裏部分代碼省略.........

// decodeOidDatum decodes bytes with specified Oid and format code into
// a datum.
func decodeOidDatum(id oid.Oid, code formatCode, b []byte) (parser.Datum, error) {
	var d parser.Datum
	switch id {
	case oid.T_bool:
		switch code {
		case formatText:
			v, err := strconv.ParseBool(string(b))
			if err != nil {
				return d, err
			}
			d = parser.MakeDBool(parser.DBool(v))
		case formatBinary:
			switch b[0] {
			case 0:
				d = parser.MakeDBool(false)
			case 1:
				d = parser.MakeDBool(true)
			default:
				return d, util.Errorf("unsupported binary bool: %q", b)
			}
		default:
			return d, util.Errorf("unsupported bool format code: %s", code)
		}
	case oid.T_int2:
		switch code {
		case formatText:
			i, err := strconv.ParseInt(string(b), 10, 64)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		case formatBinary:
			var i int16
			err := binary.Read(bytes.NewReader(b), binary.BigEndian, &i)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		default:
			return d, util.Errorf("unsupported int2 format code: %s", code)
		}
	case oid.T_int4:
		switch code {
		case formatText:
			i, err := strconv.ParseInt(string(b), 10, 64)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		case formatBinary:
			var i int32
			err := binary.Read(bytes.NewReader(b), binary.BigEndian, &i)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		default:
			return d, util.Errorf("unsupported int4 format code: %s", code)
		}
	case oid.T_int8:
		switch code {
		case formatText:
			i, err := strconv.ParseInt(string(b), 10, 64)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		case formatBinary:
			var i int64
			err := binary.Read(bytes.NewReader(b), binary.BigEndian, &i)
			if err != nil {
				return d, err
			}
			d = parser.NewDInt(parser.DInt(i))
		default:
			return d, util.Errorf("unsupported int8 format code: %s", code)
		}
	case oid.T_float4:
		switch code {
		case formatText:
			f, err := strconv.ParseFloat(string(b), 64)
			if err != nil {
				return d, err
			}
			d = parser.NewDFloat(parser.DFloat(f))
		case formatBinary:
			var f float32
			err := binary.Read(bytes.NewReader(b), binary.BigEndian, &f)
			if err != nil {
				return d, err
			}
			d = parser.NewDFloat(parser.DFloat(f))
		default:
			return d, util.Errorf("unsupported float4 format code: %s", code)
		}
	case oid.T_float8:
		switch code {
		case formatText:
//.........這裏部分代碼省略.........

func TestIndexKey(t *testing.T) {
	rng, _ := randutil.NewPseudoRand()
	var a DatumAlloc

	tests := []indexKeyTest{
		{nil, nil,
			[]parser.Datum{parser.NewDInt(10)},
			[]parser.Datum{parser.NewDInt(20)},
		},
		{[]ID{100}, nil,
			[]parser.Datum{parser.NewDInt(10), parser.NewDInt(11)},
			[]parser.Datum{parser.NewDInt(20)},
		},
		{[]ID{100, 200}, nil,
			[]parser.Datum{parser.NewDInt(10), parser.NewDInt(11), parser.NewDInt(12)},
			[]parser.Datum{parser.NewDInt(20)},
		},
		{nil, []ID{100},
			[]parser.Datum{parser.NewDInt(10)},
			[]parser.Datum{parser.NewDInt(20), parser.NewDInt(21)},
		},
		{[]ID{100}, []ID{100},
			[]parser.Datum{parser.NewDInt(10), parser.NewDInt(11)},
			[]parser.Datum{parser.NewDInt(20), parser.NewDInt(21)},
		},
		{[]ID{100}, []ID{200},
			[]parser.Datum{parser.NewDInt(10), parser.NewDInt(11)},
			[]parser.Datum{parser.NewDInt(20), parser.NewDInt(21)},
		},
		{[]ID{100, 200}, []ID{100, 300},
			[]parser.Datum{parser.NewDInt(10), parser.NewDInt(11), parser.NewDInt(12)},
			[]parser.Datum{parser.NewDInt(20), parser.NewDInt(21), parser.NewDInt(22)},
		},
	}

	for i := 0; i < 1000; i++ {
		var t indexKeyTest

		t.primaryInterleaves = make([]ID, rng.Intn(10))
		for j := range t.primaryInterleaves {
			t.primaryInterleaves[j] = ID(1 + rng.Intn(10))
		}
		valuesLen := randutil.RandIntInRange(rng, len(t.primaryInterleaves)+1, len(t.primaryInterleaves)+10)
		t.primaryValues = make([]parser.Datum, valuesLen)
		for j := range t.primaryValues {
			t.primaryValues[j] = RandDatum(rng, ColumnType_INT, true)
		}

		t.secondaryInterleaves = make([]ID, rng.Intn(10))
		for j := range t.secondaryInterleaves {
			t.secondaryInterleaves[j] = ID(1 + rng.Intn(10))
		}
		valuesLen = randutil.RandIntInRange(rng, len(t.secondaryInterleaves)+1, len(t.secondaryInterleaves)+10)
		t.secondaryValues = make([]parser.Datum, valuesLen)
		for j := range t.secondaryValues {
			t.secondaryValues[j] = RandDatum(rng, ColumnType_INT, true)
		}

		tests = append(tests, t)
	}

	for i, test := range tests {
		tableDesc, colMap := makeTableDescForTest(test)
		testValues := append(test.primaryValues, test.secondaryValues...)

		primaryKeyPrefix := MakeIndexKeyPrefix(&tableDesc, tableDesc.PrimaryIndex.ID)
		primaryKey, _, err := EncodeIndexKey(
			&tableDesc, &tableDesc.PrimaryIndex, colMap, testValues, primaryKeyPrefix)
		if err != nil {
			t.Fatal(err)
		}
		primaryValue := roachpb.MakeValueFromBytes(nil)
		primaryIndexKV := client.KeyValue{Key: primaryKey, Value: &primaryValue}

		secondaryIndexEntry, err := EncodeSecondaryIndex(
			&tableDesc, &tableDesc.Indexes[0], colMap, testValues)
		if err != nil {
			t.Fatal(err)
		}
		secondaryIndexKV := client.KeyValue{
			Key:   secondaryIndexEntry.Key,
			Value: &secondaryIndexEntry.Value,
		}

		checkEntry := func(index *IndexDescriptor, entry client.KeyValue) {
			values, err := decodeIndex(&a, &tableDesc, index, entry.Key)
			if err != nil {
				t.Fatal(err)
			}

			for j, value := range values {
				testValue := testValues[colMap[index.ColumnIDs[j]]]
				if value.Compare(testValue) != 0 {
					t.Fatalf("%d: value %d got %q but expected %q", i, j, value, testValue)
				}
			}

			indexID, _, err := DecodeIndexKeyPrefix(&a, &tableDesc, entry.Key)
			if err != nil {
				t.Fatal(err)
//.........這裏部分代碼省略.........

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

	_, sqlDB, kvDB, cleanup := sqlutils.SetupServer(t)
	defer cleanup()

	// Create a table where each row is:
	//
	//  |     a    |     b    |         sum         |         s           |
	//  |-----------------------------------------------------------------|
	//  | rowId/10 | rowId%10 | rowId/10 + rowId%10 | IntToEnglish(rowId) |

	aFn := func(row int) parser.Datum {
		return parser.NewDInt(parser.DInt(row / 10))
	}
	bFn := func(row int) parser.Datum {
		return parser.NewDInt(parser.DInt(row % 10))
	}
	sumFn := func(row int) parser.Datum {
		return parser.NewDInt(parser.DInt(row/10 + row%10))
	}

	sqlutils.CreateTable(t, sqlDB, "t",
		"a INT, b INT, sum INT, s STRING, PRIMARY KEY (a,b), INDEX bs (b,s)",
		99,
		sqlutils.ToRowFn(aFn, bFn, sumFn, sqlutils.RowEnglishFn))

	td := sqlbase.GetTableDescriptor(kvDB, "test", "t")

	makeIndexSpan := func(start, end int) TableReaderSpan {
		var span roachpb.Span
		prefix := roachpb.Key(sqlbase.MakeIndexKeyPrefix(td.ID, td.Indexes[0].ID))
		span.Key = append(prefix, encoding.EncodeVarintAscending(nil, int64(start))...)
		span.EndKey = append(span.EndKey, prefix...)
		span.EndKey = append(span.EndKey, encoding.EncodeVarintAscending(nil, int64(end))...)
		return TableReaderSpan{Span: span}
	}

	testCases := []struct {
		spec     TableReaderSpec
		expected string
	}{
		{
			spec: TableReaderSpec{
				Filter:        Expression{Expr: "$2 < 5 AND $1 != 3"}, // sum < 5 && b != 3
				OutputColumns: []uint32{0, 1},
			},
			expected: "[[0 1] [0 2] [0 4] [1 0] [1 1] [1 2] [2 0] [2 1] [2 2] [3 0] [3 1] [4 0]]",
		},
		{
			spec: TableReaderSpec{
				Filter:        Expression{Expr: "$2 < 5 AND $1 != 3"},
				OutputColumns: []uint32{3}, // s
				HardLimit:     4,
			},
			expected: "[['one'] ['two'] ['four'] ['one-zero']]",
		},
		{
			spec: TableReaderSpec{
				IndexIdx:      1,
				Reverse:       true,
				Spans:         []TableReaderSpan{makeIndexSpan(4, 6)},
				Filter:        Expression{Expr: "$0 < 3"}, // sum < 8
				OutputColumns: []uint32{0, 1},
				SoftLimit:     1,
			},
			expected: "[[2 5] [1 5] [0 5] [2 4] [1 4] [0 4]]",
		},
	}

	for _, c := range testCases {
		ts := c.spec
		ts.Table = *td

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

		out := &RowBuffer{}
		tr, err := newTableReader(&ts, txn, out, &parser.EvalContext{})
		if err != nil {
			t.Fatal(err)
		}
		tr.Run(nil)
		if out.err != nil {
			t.Fatal(out.err)
		}
		if !out.closed {
			t.Fatalf("output RowReceiver not closed")
		}
		if result := out.rows.String(); result != c.expected {
			t.Errorf("invalid results: %s, expected %s'", result, c.expected)
		}
	}
}

func dIntFnOrNull(fn func() (int32, bool)) parser.Datum {
	if n, ok := fn(); ok {
		return parser.NewDInt(parser.DInt(n))
	}
	return parser.DNull
}

func TestEncDatum(t *testing.T) {
	a := &DatumAlloc{}
	x := &EncDatum{}
	if !x.IsUnset() {
		t.Errorf("empty EncDatum should be unset")
	}

	if _, ok := x.Encoding(); ok {
		t.Errorf("empty EncDatum has an encoding")
	}

	x.SetDatum(ColumnType_INT, parser.NewDInt(5))
	if x.IsUnset() {
		t.Errorf("unset after SetDatum()")
	}

	encoded, err := x.Encode(a, DatumEncoding_ASCENDING_KEY, nil)
	if err != nil {
		t.Fatal(err)
	}

	y := &EncDatum{}
	y.SetEncoded(ColumnType_INT, DatumEncoding_ASCENDING_KEY, encoded)

	if y.IsUnset() {
		t.Errorf("unset after SetEncoded()")
	}
	if enc, ok := y.Encoding(); !ok {
		t.Error("no encoding after SetEncoded")
	} else if enc != DatumEncoding_ASCENDING_KEY {
		t.Errorf("invalid encoding %d", enc)
	}
	err = y.Decode(a)
	if err != nil {
		t.Fatal(err)
	}
	if cmp := y.Datum.Compare(x.Datum); cmp != 0 {
		t.Errorf("Datums should be equal, cmp = %d", cmp)
	}

	enc2, err := y.Encode(a, DatumEncoding_DESCENDING_KEY, nil)
	if err != nil {
		t.Fatal(err)
	}
	// y's encoding should not change.
	if enc, ok := y.Encoding(); !ok {
		t.Error("no encoding")
	} else if enc != DatumEncoding_ASCENDING_KEY {
		t.Errorf("invalid encoding %d", enc)
	}
	x.SetEncoded(ColumnType_INT, DatumEncoding_DESCENDING_KEY, enc2)
	if enc, ok := x.Encoding(); !ok {
		t.Error("no encoding")
	} else if enc != DatumEncoding_DESCENDING_KEY {
		t.Errorf("invalid encoding %d", enc)
	}
	err = x.Decode(a)
	if err != nil {
		t.Fatal(err)
	}
	if cmp := y.Datum.Compare(x.Datum); cmp != 0 {
		t.Errorf("Datums should be equal, cmp = %d", cmp)
	}
}