// SetUIData is an endpoint that stores the given key/value pairs in the
// system.ui table. See GetUIData for more details on semantics.
func (s *adminServer) SetUIData(
	ctx context.Context, req *serverpb.SetUIDataRequest,
) (*serverpb.SetUIDataResponse, error) {
	if len(req.KeyValues) == 0 {
		return nil, grpc.Errorf(codes.InvalidArgument, "KeyValues cannot be empty")
	}

	args := sql.SessionArgs{User: s.getUser(req)}
	session := s.NewSessionForRPC(ctx, args)
	defer session.Finish(s.server.sqlExecutor)

	for key, val := range req.KeyValues {
		// Do an upsert of the key. We update each key in a separate transaction to
		// avoid long-running transactions and possible deadlocks.
		br := s.server.sqlExecutor.ExecuteStatements(session, "BEGIN;", nil)
		defer br.Close()
		if err := s.checkQueryResults(br.ResultList, 1); err != nil {
			return nil, s.serverError(err)
		}

		// See if the key already exists.
		resp, err := s.getUIData(session, s.getUser(req), []string{key})
		if err != nil {
			return nil, s.serverError(err)
		}
		_, alreadyExists := resp.KeyValues[key]

		// INSERT or UPDATE as appropriate.
		if alreadyExists {
			query := "UPDATE system.ui SET value = $1, lastUpdated = NOW() WHERE key = $2; COMMIT;"
			qargs := parser.NewPlaceholderInfo()
			qargs.SetValue(`1`, parser.NewDString(string(val)))
			qargs.SetValue(`2`, parser.NewDString(key))
			r := s.server.sqlExecutor.ExecuteStatements(session, query, qargs)
			defer r.Close()
			if err := s.checkQueryResults(r.ResultList, 2); err != nil {
				return nil, s.serverError(err)
			}
			if a, e := r.ResultList[0].RowsAffected, 1; a != e {
				return nil, s.serverErrorf("rows affected %d != expected %d", a, e)
			}
		} else {
			query := "INSERT INTO system.ui (key, value, lastUpdated) VALUES ($1, $2, NOW()); COMMIT;"
			qargs := parser.NewPlaceholderInfo()
			qargs.SetValue(`1`, parser.NewDString(key))
			qargs.SetValue(`2`, parser.NewDBytes(parser.DBytes(val)))
			r := s.server.sqlExecutor.ExecuteStatements(session, query, qargs)
			defer r.Close()
			if err := s.checkQueryResults(r.ResultList, 2); err != nil {
				return nil, s.serverError(err)
			}
			if a, e := r.ResultList[0].RowsAffected, 1; a != e {
				return nil, s.serverErrorf("rows affected %d != expected %d", a, e)
			}
		}
	}

	return &serverpb.SetUIDataResponse{}, 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)
	}
}

// DecodeTableValue decodes a value encoded by EncodeTableValue.
func DecodeTableValue(a *DatumAlloc, valType parser.Type, b []byte) (parser.Datum, []byte, error) {
	_, dataOffset, _, typ, err := encoding.DecodeValueTag(b)
	if err != nil {
		return nil, b, err
	}
	if typ == encoding.Null {
		return parser.DNull, b[dataOffset:], nil
	}
	switch valType {
	case parser.TypeBool:
		var x bool
		b, x, err = encoding.DecodeBoolValue(b)
		// No need to chunk allocate DBool as MakeDBool returns either
		// parser.DBoolTrue or parser.DBoolFalse.
		return parser.MakeDBool(parser.DBool(x)), b, err
	case parser.TypeInt:
		var i int64
		b, i, err = encoding.DecodeIntValue(b)
		return a.NewDInt(parser.DInt(i)), b, err
	case parser.TypeFloat:
		var f float64
		b, f, err = encoding.DecodeFloatValue(b)
		return a.NewDFloat(parser.DFloat(f)), b, err
	case parser.TypeDecimal:
		var d *inf.Dec
		b, d, err = encoding.DecodeDecimalValue(b)
		dd := a.NewDDecimal(parser.DDecimal{})
		dd.Set(d)
		return dd, b, err
	case parser.TypeString:
		var data []byte
		b, data, err = encoding.DecodeBytesValue(b)
		return a.NewDString(parser.DString(data)), b, err
	case parser.TypeBytes:
		var data []byte
		b, data, err = encoding.DecodeBytesValue(b)
		return a.NewDBytes(parser.DBytes(data)), b, err
	case parser.TypeDate:
		var i int64
		b, i, err = encoding.DecodeIntValue(b)
		return a.NewDDate(parser.DDate(i)), b, err
	case parser.TypeTimestamp:
		var t time.Time
		b, t, err = encoding.DecodeTimeValue(b)
		return a.NewDTimestamp(parser.DTimestamp{Time: t}), b, err
	case parser.TypeTimestampTZ:
		var t time.Time
		b, t, err = encoding.DecodeTimeValue(b)
		return a.NewDTimestampTZ(parser.DTimestampTZ{Time: t}), b, err
	case parser.TypeInterval:
		var d duration.Duration
		b, d, err = encoding.DecodeDurationValue(b)
		return a.NewDInterval(parser.DInterval{Duration: d}), b, err
	default:
		return nil, nil, errors.Errorf("TODO(pmattis): decoded index value: %s", valType)
	}
}

// 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))}
	case ColumnType_INT_ARRAY:
		// TODO(cuongdo): we don't support for persistence of arrays yet
		return parser.DNull
	default:
		panic(fmt.Sprintf("invalid type %s", typ))
	}
}

// TestAdminAPIZoneDetails verifies the zone configuration information returned
// for both DatabaseDetailsResponse AND TableDetailsResponse.
func TestAdminAPIZoneDetails(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, _, _ := serverutils.StartServer(t, base.TestServerArgs{})
	defer s.Stopper().Stop()
	ts := s.(*TestServer)

	// Create database and table.
	ac := log.AmbientContext{Tracer: tracing.NewTracer()}
	ctx, span := ac.AnnotateCtxWithSpan(context.Background(), "test")
	defer span.Finish()
	session := sql.NewSession(
		ctx, sql.SessionArgs{User: security.RootUser}, ts.sqlExecutor, nil, &sql.MemoryMetrics{})
	session.StartUnlimitedMonitor()
	setupQueries := []string{
		"CREATE DATABASE test",
		"CREATE TABLE test.tbl (val STRING)",
	}
	for _, q := range setupQueries {
		res := ts.sqlExecutor.ExecuteStatements(session, q, nil)
		defer res.Close()
		if res.ResultList[0].Err != nil {
			t.Fatalf("error executing '%s': %s", q, res.ResultList[0].Err)
		}
	}

	// Function to verify the zone for table "test.tbl" as returned by the Admin
	// API.
	verifyTblZone := func(
		expectedZone config.ZoneConfig, expectedLevel serverpb.ZoneConfigurationLevel,
	) {
		var resp serverpb.TableDetailsResponse
		if err := getAdminJSONProto(s, "databases/test/tables/tbl", &resp); err != nil {
			t.Fatal(err)
		}
		if a, e := &resp.ZoneConfig, &expectedZone; !proto.Equal(a, e) {
			t.Errorf("actual table zone config %v did not match expected value %v", a, e)
		}
		if a, e := resp.ZoneConfigLevel, expectedLevel; a != e {
			t.Errorf("actual table ZoneConfigurationLevel %s did not match expected value %s", a, e)
		}
		if t.Failed() {
			t.FailNow()
		}
	}

	// Function to verify the zone for database "test" as returned by the Admin
	// API.
	verifyDbZone := func(
		expectedZone config.ZoneConfig, expectedLevel serverpb.ZoneConfigurationLevel,
	) {
		var resp serverpb.DatabaseDetailsResponse
		if err := getAdminJSONProto(s, "databases/test", &resp); err != nil {
			t.Fatal(err)
		}
		if a, e := &resp.ZoneConfig, &expectedZone; !proto.Equal(a, e) {
			t.Errorf("actual db zone config %v did not match expected value %v", a, e)
		}
		if a, e := resp.ZoneConfigLevel, expectedLevel; a != e {
			t.Errorf("actual db ZoneConfigurationLevel %s did not match expected value %s", a, e)
		}
		if t.Failed() {
			t.FailNow()
		}
	}

	// Function to store a zone config for a given object ID.
	setZone := func(zoneCfg config.ZoneConfig, id sqlbase.ID) {
		zoneBytes, err := zoneCfg.Marshal()
		if err != nil {
			t.Fatal(err)
		}
		const query = `INSERT INTO system.zones VALUES($1, $2)`
		params := parser.NewPlaceholderInfo()
		params.SetValue(`1`, parser.NewDInt(parser.DInt(id)))
		params.SetValue(`2`, parser.NewDBytes(parser.DBytes(zoneBytes)))
		res := ts.sqlExecutor.ExecuteStatements(session, query, params)
		defer res.Close()
		if res.ResultList[0].Err != nil {
			t.Fatalf("error executing '%s': %s", query, res.ResultList[0].Err)
		}
	}

	// Verify zone matches cluster default.
	verifyDbZone(config.DefaultZoneConfig(), serverpb.ZoneConfigurationLevel_CLUSTER)
	verifyTblZone(config.DefaultZoneConfig(), serverpb.ZoneConfigurationLevel_CLUSTER)

	// Get ID path for table. This will be an array of three IDs, containing the ID of the root namespace,
	// the database, and the table (in that order).
	idPath, err := ts.admin.queryDescriptorIDPath(session, []string{"test", "tbl"})
	if err != nil {
		t.Fatal(err)
	}

	// Apply zone configuration to database and check again.
	dbZone := config.ZoneConfig{
		RangeMinBytes: 456,
	}
	setZone(dbZone, idPath[1])
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		inserts := make([][]string, 0, limit)
		i := 0
		for i < limit {
			vals := make([]driver.Value, len(cols)+len(pkcols))
			if err := rows.Next(vals); err == io.EOF {
				break
			} else if err != nil {
				return err
			}
			if pk == nil {
				q = fmt.Sprintf(bs, wbuf.String())
			}
			pk = vals[:len(index)]
			vals = vals[len(index):]
			ivals := make([]string, len(vals))
			// Values need to be correctly encoded for INSERT statements in a text file.
			for si, sv := range vals {
				switch t := sv.(type) {
				case nil:
					ivals[si] = "NULL"
				case bool:
					ivals[si] = parser.MakeDBool(parser.DBool(t)).String()
				case int64:
					ivals[si] = parser.NewDInt(parser.DInt(t)).String()
				case float64:
					ivals[si] = parser.NewDFloat(parser.DFloat(t)).String()
				case string:
					ivals[si] = parser.NewDString(t).String()
				case []byte:
					switch ct := coltypes[cols[si]]; ct {
					case "INTERVAL":
						ivals[si] = fmt.Sprintf("'%s'", t)
					case "BYTES":
						ivals[si] = parser.NewDBytes(parser.DBytes(t)).String()
					default:
						// STRING and DECIMAL types can have optional length
						// suffixes, so only examine the prefix of the type.
						if strings.HasPrefix(coltypes[cols[si]], "STRING") {
							ivals[si] = parser.NewDString(string(t)).String()
						} else if strings.HasPrefix(coltypes[cols[si]], "DECIMAL") {
							ivals[si] = string(t)
						} else {
							panic(errors.Errorf("unknown []byte type: %s, %v: %s", t, cols[si], coltypes[cols[si]]))
						}
					}
				case time.Time:
					var d parser.Datum
					ct := coltypes[cols[si]]
					switch ct {
					case "DATE":
						d = parser.NewDDateFromTime(t, time.UTC)
					case "TIMESTAMP":
						d = parser.MakeDTimestamp(t, time.Nanosecond)
					case "TIMESTAMP WITH TIME ZONE":
						d = parser.MakeDTimestampTZ(t, time.Nanosecond)
					default:
						panic(errors.Errorf("unknown timestamp type: %s, %v: %s", t, cols[si], coltypes[cols[si]]))
					}
					ivals[si] = fmt.Sprintf("'%s'", d)
				default:
					panic(errors.Errorf("unknown field type: %T (%s)", t, cols[si]))
				}
			}
			inserts = append(inserts, ivals)
			i++
		}

// DecodeTableKey decodes a table key/value.
func DecodeTableKey(
	a *DatumAlloc, valType parser.Type, key []byte, dir encoding.Direction,
) (parser.Datum, []byte, error) {
	if (dir != encoding.Ascending) && (dir != encoding.Descending) {
		return nil, nil, errors.Errorf("invalid direction: %d", dir)
	}
	var isNull bool
	if key, isNull = encoding.DecodeIfNull(key); isNull {
		return parser.DNull, key, nil
	}
	var rkey []byte
	var err error
	switch valType {
	case parser.TypeBool:
		var i int64
		if dir == encoding.Ascending {
			rkey, i, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, i, err = encoding.DecodeVarintDescending(key)
		}
		// No need to chunk allocate DBool as MakeDBool returns either
		// parser.DBoolTrue or parser.DBoolFalse.
		return parser.MakeDBool(parser.DBool(i != 0)), rkey, err
	case parser.TypeInt:
		var i int64
		if dir == encoding.Ascending {
			rkey, i, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, i, err = encoding.DecodeVarintDescending(key)
		}
		return a.NewDInt(parser.DInt(i)), rkey, err
	case parser.TypeFloat:
		var f float64
		if dir == encoding.Ascending {
			rkey, f, err = encoding.DecodeFloatAscending(key)
		} else {
			rkey, f, err = encoding.DecodeFloatDescending(key)
		}
		return a.NewDFloat(parser.DFloat(f)), rkey, err
	case parser.TypeDecimal:
		var d *inf.Dec
		if dir == encoding.Ascending {
			rkey, d, err = encoding.DecodeDecimalAscending(key, nil)
		} else {
			rkey, d, err = encoding.DecodeDecimalDescending(key, nil)
		}
		dd := a.NewDDecimal(parser.DDecimal{})
		dd.Set(d)
		return dd, rkey, err
	case parser.TypeString:
		var r string
		if dir == encoding.Ascending {
			rkey, r, err = encoding.DecodeUnsafeStringAscending(key, nil)
		} else {
			rkey, r, err = encoding.DecodeUnsafeStringDescending(key, nil)
		}
		return a.NewDString(parser.DString(r)), rkey, err
	case parser.TypeBytes:
		var r []byte
		if dir == encoding.Ascending {
			rkey, r, err = encoding.DecodeBytesAscending(key, nil)
		} else {
			rkey, r, err = encoding.DecodeBytesDescending(key, nil)
		}
		return a.NewDBytes(parser.DBytes(r)), rkey, err
	case parser.TypeDate:
		var t int64
		if dir == encoding.Ascending {
			rkey, t, err = encoding.DecodeVarintAscending(key)
		} else {
			rkey, t, err = encoding.DecodeVarintDescending(key)
		}
		return a.NewDDate(parser.DDate(t)), rkey, err
	case parser.TypeTimestamp:
		var t time.Time
		if dir == encoding.Ascending {
			rkey, t, err = encoding.DecodeTimeAscending(key)
		} else {
			rkey, t, err = encoding.DecodeTimeDescending(key)
		}
		return a.NewDTimestamp(parser.DTimestamp{Time: t}), rkey, err
	case parser.TypeTimestampTZ:
		var t time.Time
		if dir == encoding.Ascending {
			rkey, t, err = encoding.DecodeTimeAscending(key)
		} else {
			rkey, t, err = encoding.DecodeTimeDescending(key)
		}
		return a.NewDTimestampTZ(parser.DTimestampTZ{Time: t}), rkey, err
	case parser.TypeInterval:
		var d duration.Duration
		if dir == encoding.Ascending {
			rkey, d, err = encoding.DecodeDurationAscending(key)
		} else {
			rkey, d, err = encoding.DecodeDurationDescending(key)
		}
		return a.NewDInterval(parser.DInterval{Duration: d}), rkey, err
	default:
		return nil, nil, errors.Errorf("TODO(pmattis): decoded index key: %s", valType)
//.........这里部分代码省略.........

// UnmarshalColumnValue decodes the value from a key-value pair using the type
// expected by the column. An error is returned if the value's type does not
// match the column's type.
func UnmarshalColumnValue(
	a *DatumAlloc, kind ColumnType_Kind, value *roachpb.Value,
) (parser.Datum, error) {
	if value == nil {
		return parser.DNull, nil
	}

	switch kind {
	case ColumnType_BOOL:
		v, err := value.GetBool()
		if err != nil {
			return nil, err
		}
		return parser.MakeDBool(parser.DBool(v)), nil
	case ColumnType_INT:
		v, err := value.GetInt()
		if err != nil {
			return nil, err
		}
		return a.NewDInt(parser.DInt(v)), nil
	case ColumnType_FLOAT:
		v, err := value.GetFloat()
		if err != nil {
			return nil, err
		}
		return a.NewDFloat(parser.DFloat(v)), nil
	case ColumnType_DECIMAL:
		v, err := value.GetDecimal()
		if err != nil {
			return nil, err
		}
		dd := a.NewDDecimal(parser.DDecimal{})
		dd.Set(v)
		return dd, nil
	case ColumnType_STRING:
		v, err := value.GetBytes()
		if err != nil {
			return nil, err
		}
		return a.NewDString(parser.DString(v)), nil
	case ColumnType_BYTES:
		v, err := value.GetBytes()
		if err != nil {
			return nil, err
		}
		return a.NewDBytes(parser.DBytes(v)), nil
	case ColumnType_DATE:
		v, err := value.GetInt()
		if err != nil {
			return nil, err
		}
		return a.NewDDate(parser.DDate(v)), nil
	case ColumnType_TIMESTAMP:
		v, err := value.GetTime()
		if err != nil {
			return nil, err
		}
		return a.NewDTimestamp(parser.DTimestamp{Time: v}), nil
	case ColumnType_TIMESTAMPTZ:
		v, err := value.GetTime()
		if err != nil {
			return nil, err
		}
		return a.NewDTimestampTZ(parser.DTimestampTZ{Time: v}), nil
	case ColumnType_INTERVAL:
		d, err := value.GetDuration()
		if err != nil {
			return nil, err
		}
		return a.NewDInterval(parser.DInterval{Duration: d}), nil
	default:
		return nil, errors.Errorf("unsupported column type: %s", kind)
	}
}

//.........这里部分代码省略.........
			switch alloc.pgNum.sign {
			case pgNumericPos:
			case pgNumericNeg:
				alloc.dd.Neg(&alloc.dd.Dec)
			default:
				return d, errors.Errorf("unsupported numeric sign: %d", alloc.pgNum.sign)
			}

			d = &alloc.dd
		default:
			return d, errors.Errorf("unsupported numeric format code: %d", code)
		}
	case oid.T_text, oid.T_varchar:
		switch code {
		case formatText, formatBinary:
			d = parser.NewDString(string(b))
		default:
			return d, errors.Errorf("unsupported text format code: %d", code)
		}
	case oid.T_bytea:
		switch code {
		case formatText:
			// http://www.postgresql.org/docs/current/static/datatype-binary.html#AEN5667
			// Code cribbed from github.com/lib/pq.

			// We only support hex encoding.
			if len(b) >= 2 && bytes.Equal(b[:2], []byte("\\x")) {
				b = b[2:] // trim off leading "\\x"
				result := make([]byte, hex.DecodedLen(len(b)))
				_, err := hex.Decode(result, b)
				if err != nil {
					return d, err
				}
				d = parser.NewDBytes(parser.DBytes(result))
			} else {
				return d, errors.Errorf("unsupported bytea encoding: %q", b)
			}
		case formatBinary:
			d = parser.NewDBytes(parser.DBytes(b))
		default:
			return d, errors.Errorf("unsupported bytea format code: %d", code)
		}
	case oid.T_timestamp:
		switch code {
		case formatText:
			ts, err := parseTs(string(b))
			if err != nil {
				return d, errors.Errorf("could not parse string %q as timestamp", b)
			}
			d = parser.MakeDTimestamp(ts, time.Microsecond)
		case formatBinary:
			if len(b) < 8 {
				return d, errors.Errorf("timestamp requires 8 bytes for binary format")
			}
			i := int64(binary.BigEndian.Uint64(b))
			d = parser.MakeDTimestamp(pgBinaryToTime(i), time.Microsecond)
		default:
			return d, errors.Errorf("unsupported timestamp format code: %d", code)
		}
	case oid.T_timestamptz:
		switch code {
		case formatText:
			ts, err := parseTs(string(b))
			if err != nil {
				return d, errors.Errorf("could not parse string %q as timestamp", b)
			}

// 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, null bool) parser.Datum {
	if null && rng.Intn(10) == 0 {
		return parser.DNull
	}
	switch typ.Kind {
	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))}
	case ColumnType_COLLATEDSTRING:
		if typ.Locale == nil {
			panic("locale is required for COLLATEDSTRING")
		}
		// Generate a random Unicode string.
		var buf bytes.Buffer
		n := rng.Intn(10)
		for i := 0; i < n; i++ {
			var r rune
			for {
				r = rune(rng.Intn(unicode.MaxRune + 1))
				if !unicode.Is(unicode.C, r) {
					break
				}
			}
			buf.WriteRune(r)
		}
		return parser.NewDCollatedString(buf.String(), *typ.Locale, &parser.CollationEnvironment{})
	case ColumnType_INT_ARRAY:
		// TODO(cuongdo): we don't support for persistence of arrays yet
		return parser.DNull
	default:
		panic(fmt.Sprintf("invalid type %s", typ.String()))
	}
}