Agrega datos para un esquema complejo

Demuestra cómo agregar datos complejos a una tabla con una transmisión predeterminada.

Muestra de código

Go

Antes de probar este ejemplo, sigue las instrucciones de configuración para Go incluidas en la guía de inicio rápido de BigQuery sobre cómo usar bibliotecas cliente. Para obtener más información, consulta la documentación de referencia de la API de BigQuery para Go.

Para autenticarte en BigQuery, configura las credenciales predeterminadas de la aplicación. Si deseas obtener más información, consulta Configura la autenticación para bibliotecas cliente.


import (
	"context"
	"fmt"
	"io"
	"math/rand"
	"time"

	"cloud.google.com/go/bigquery/storage/managedwriter"
	"cloud.google.com/go/bigquery/storage/managedwriter/adapt"
	"github.com/GoogleCloudPlatform/golang-samples/bigquery/snippets/managedwriter/exampleproto"
	"google.golang.org/protobuf/proto"
)

// generateExampleMessages generates a slice of serialized protobuf messages using a statically defined
// and compiled protocol buffer file, and returns the binary serialized representation.
func generateExampleDefaultMessages(numMessages int) ([][]byte, error) {
	msgs := make([][]byte, numMessages)
	for i := 0; i < numMessages; i++ {

		// instantiate a new random source.
		random := rand.New(
			rand.NewSource(time.Now().UnixNano()),
		)

		// Our example data embeds an array of structs, so we'll construct that first.
		sl := make([]*exampleproto.SampleStruct, 5)
		for i := 0; i < int(random.Int63n(5)+1); i++ {
			sl[i] = &exampleproto.SampleStruct{
				SubIntCol: proto.Int64(random.Int63()),
			}
		}

		m := &exampleproto.SampleData{
			BoolCol:    proto.Bool(true),
			BytesCol:   []byte("some bytes"),
			Float64Col: proto.Float64(3.14),
			Int64Col:   proto.Int64(123),
			StringCol:  proto.String("example string value"),

			// These types require special encoding/formatting to transmit.

			// DATE values are number of days since the Unix epoch.

			DateCol: proto.Int32(int32(time.Now().UnixNano() / 86400000000000)),

			// DATETIME uses the literal format.
			DatetimeCol: proto.String("2022-01-01 12:13:14.000000"),

			// GEOGRAPHY uses Well-Known-Text (WKT) format.
			GeographyCol: proto.String("POINT(-122.350220 47.649154)"),

			// NUMERIC and BIGNUMERIC can be passed as string, or more efficiently
			// using a packed byte representation.
			NumericCol:    proto.String("99999999999999999999999999999.999999999"),
			BignumericCol: proto.String("578960446186580977117854925043439539266.34992332820282019728792003956564819967"),

			// TIME also uses literal format.
			TimeCol: proto.String("12:13:14.000000"),

			// TIMESTAMP uses microseconds since Unix epoch.
			TimestampCol: proto.Int64(time.Now().UnixNano() / 1000),

			// Int64List is an array of INT64 types.
			Int64List: []int64{2, 4, 6, 8},

			// This is a required field in the schema, and thus must be present.
			RowNum: proto.Int64(23),

			// StructCol is a single nested message.
			StructCol: &exampleproto.SampleStruct{
				SubIntCol: proto.Int64(random.Int63()),
			},

			// StructList is a repeated array of a nested message.
			StructList: sl,
		}

		b, err := proto.Marshal(m)
		if err != nil {
			return nil, fmt.Errorf("error generating message %d: %w", i, err)
		}
		msgs[i] = b
	}
	return msgs, nil
}

// appendToDefaultStream demonstrates using the managedwriter package to write some example data
// to a default stream.
func appendToDefaultStream(w io.Writer, projectID, datasetID, tableID string) error {
	// projectID := "myproject"
	// datasetID := "mydataset"
	// tableID := "mytable"

	ctx := context.Background()
	// Instantiate a managedwriter client to handle interactions with the service.
	client, err := managedwriter.NewClient(ctx, projectID,
		managedwriter.WithMultiplexing(), // Enables connection sharing.
	)
	if err != nil {
		return fmt.Errorf("managedwriter.NewClient: %w", err)
	}
	// Close the client when we exit the function.
	defer client.Close()

	// We need to communicate the descriptor of the protocol buffer message we're using, which
	// is analagous to the "schema" for the message.  Both SampleData and SampleStruct are
	// two distinct messages in the compiled proto file, so we'll use adapt.NormalizeDescriptor
	// to unify them into a single self-contained descriptor representation.
	var m *exampleproto.SampleData
	descriptorProto, err := adapt.NormalizeDescriptor(m.ProtoReflect().Descriptor())
	if err != nil {
		return fmt.Errorf("NormalizeDescriptor: %w", err)
	}

	// Build the formatted reference to the destination table.
	tableReference := managedwriter.TableParentFromParts(projectID, datasetID, tableID)

	// Instantiate a ManagedStream, which manages low level details like connection state and provides
	// additional features like a future-like callback for appends, etc.  Default streams are provided by
	// the system, so there's no need to create them.
	managedStream, err := client.NewManagedStream(ctx,
		managedwriter.WithType(managedwriter.DefaultStream),
		managedwriter.WithDestinationTable(tableReference),
		managedwriter.WithSchemaDescriptor(descriptorProto),
	)
	if err != nil {
		return fmt.Errorf("NewManagedStream: %w", err)
	}
	// Automatically close the writer when we're done.
	defer managedStream.Close()

	// First, we'll append a single row.
	rows, err := generateExampleDefaultMessages(1)
	if err != nil {
		return fmt.Errorf("generateExampleMessages: %w", err)
	}

	// We can append data asyncronously, so we'll check our appends at the end.
	var results []*managedwriter.AppendResult

	result, err := managedStream.AppendRows(ctx, rows)
	if err != nil {
		return fmt.Errorf("AppendRows first call error: %w", err)
	}
	results = append(results, result)

	// This time, we'll append three more rows in a single request.
	rows, err = generateExampleMessages(3)
	if err != nil {
		return fmt.Errorf("generateExampleMessages: %w", err)
	}
	result, err = managedStream.AppendRows(ctx, rows)
	if err != nil {
		return fmt.Errorf("AppendRows second call error: %w", err)
	}
	results = append(results, result)

	// Finally, we'll append two more rows.
	rows, err = generateExampleMessages(2)
	if err != nil {
		return fmt.Errorf("generateExampleMessages: %w", err)
	}
	result, err = managedStream.AppendRows(ctx, rows)
	if err != nil {
		return fmt.Errorf("AppendRows third call error: %w", err)
	}
	results = append(results, result)

	// We've been collecting references to our status callbacks to allow us to append in a faster
	// asynchronous fashion.  Normally you could do this in another goroutine or similar, but for
	// this example we'll now iterate through those results and verify they were all successful.
	for k, v := range results {
		// GetResult blocks until we receive a response from the API.
		recvOffset, err := v.GetResult(ctx)
		if err != nil {
			return fmt.Errorf("append %d returned error: %w", k, err)
		}
		fmt.Fprintf(w, "Successfully appended data at offset %d.\n", recvOffset)
	}

	// This stream is a default stream, which means it doesn't require any form of finalization
	// or commit.  The rows were automatically committed to the table.
	return nil
}

¿Qué sigue?

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