Inserisci, aggiorna ed elimina dati utilizzando le mutazioni

Questa pagina descrive come inserire, aggiornare ed eliminare i dati utilizzando le mutazioni. Una mutazione rappresenta una sequenza di inserti, aggiornamenti ed eliminazioni che Spanner applica a livello atomico a diverse righe e tabelle in un database di Spanner.

Anche se puoi eseguire il commit delle mutazioni utilizzando gRPC o REST, è più comune accedere alle API tramite le librerie client.

In questa pagina vengono mostrate le attività di base di inserimento, aggiornamento ed eliminazione. Puoi trovare altri esempi nei tutorial introduttivi.

Se devi eseguire il commit di un numero elevato di scritture cieche, ma non hai bisogno di una transazione atomica, puoi modificare in blocco le tabelle Spanner utilizzando la scrittura batch. Per ulteriori informazioni, consulta Modificare i dati tramite scritture batch.

Inserimento di nuove righe in una tabella

C++

Puoi scrivere i dati utilizzando la funzione InsertMutationBuilder(). Client::Commit() aggiunge nuove righe a una tabella. Tutti gli inserti in un singolo batch vengono applicati a livello atomico.

Questo codice mostra come scrivere i dati:

void InsertData(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  auto insert_singers = spanner::InsertMutationBuilder(
                            "Singers", {"SingerId", "FirstName", "LastName"})
                            .EmplaceRow(1, "Marc", "Richards")
                            .EmplaceRow(2, "Catalina", "Smith")
                            .EmplaceRow(3, "Alice", "Trentor")
                            .EmplaceRow(4, "Lea", "Martin")
                            .EmplaceRow(5, "David", "Lomond")
                            .Build();

  auto insert_albums = spanner::InsertMutationBuilder(
                           "Albums", {"SingerId", "AlbumId", "AlbumTitle"})
                           .EmplaceRow(1, 1, "Total Junk")
                           .EmplaceRow(1, 2, "Go, Go, Go")
                           .EmplaceRow(2, 1, "Green")
                           .EmplaceRow(2, 2, "Forever Hold Your Peace")
                           .EmplaceRow(2, 3, "Terrified")
                           .Build();

  auto commit_result =
      client.Commit(spanner::Mutations{insert_singers, insert_albums});
  if (!commit_result) throw std::move(commit_result).status();
  std::cout << "Insert was successful [spanner_insert_data]\n";
}

C#

Puoi inserire i dati utilizzando il metodo connection.CreateInsertCommand(), che crea un nuovo SpannerCommand per inserire righe in una tabella. Il metodo SpannerCommand.ExecuteNonQueryAsync() aggiunge nuove righe alla tabella.

Nota: puoi eseguire più transazioni in parallelo utilizzando un singolo oggetto SpannerConnection. Quando esegui transazioni aggiuntive, devi assicurarti che l'oggetto SpannerConnection sia nello stato Open prima di eseguire altri comandi di transazione chiamando il metodo SpannerCommand.ExecuteNonQueryAsync(), come mostrato nell'esempio seguente.

Questo codice mostra come inserire i dati:

using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

public class InsertDataAsyncSample
{
    public class Singer
    {
        public int SingerId { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }

    public class Album
    {
        public int SingerId { get; set; }
        public int AlbumId { get; set; }
        public string AlbumTitle { get; set; }
    }

    public async Task InsertDataAsync(string projectId, string instanceId, string databaseId)
    {
        string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
        List<Singer> singers = new List<Singer>
        {
            new Singer { SingerId = 1, FirstName = "Marc", LastName = "Richards" },
            new Singer { SingerId = 2, FirstName = "Catalina", LastName = "Smith" },
            new Singer { SingerId = 3, FirstName = "Alice", LastName = "Trentor" },
            new Singer { SingerId = 4, FirstName = "Lea", LastName = "Martin" },
            new Singer { SingerId = 5, FirstName = "David", LastName = "Lomond" },
        };
        List<Album> albums = new List<Album>
        {
            new Album { SingerId = 1, AlbumId = 1, AlbumTitle = "Total Junk" },
            new Album { SingerId = 1, AlbumId = 2, AlbumTitle = "Go, Go, Go" },
            new Album { SingerId = 2, AlbumId = 1, AlbumTitle = "Green" },
            new Album { SingerId = 2, AlbumId = 2, AlbumTitle = "Forever Hold your Peace" },
            new Album { SingerId = 2, AlbumId = 3, AlbumTitle = "Terrified" },
        };

        // Create connection to Cloud Spanner.
        using var connection = new SpannerConnection(connectionString);
        await connection.OpenAsync();

        await connection.RunWithRetriableTransactionAsync(async transaction =>
        {
            await Task.WhenAll(singers.Select(singer =>
            {
                // Insert rows into the Singers table.
                using var cmd = connection.CreateInsertCommand("Singers", new SpannerParameterCollection
                {
                        { "SingerId", SpannerDbType.Int64, singer.SingerId },
                        { "FirstName", SpannerDbType.String, singer.FirstName },
                        { "LastName", SpannerDbType.String, singer.LastName }
                });
                cmd.Transaction = transaction;
                return cmd.ExecuteNonQueryAsync();
            }));

            await Task.WhenAll(albums.Select(album =>
            {
                // Insert rows into the Albums table.
                using var cmd = connection.CreateInsertCommand("Albums", new SpannerParameterCollection
                {
                        { "SingerId", SpannerDbType.Int64, album.SingerId },
                        { "AlbumId", SpannerDbType.Int64, album.AlbumId },
                        { "AlbumTitle", SpannerDbType.String,album.AlbumTitle }
                });
                cmd.Transaction = transaction;
                return cmd.ExecuteNonQueryAsync();
            }));
        });
        Console.WriteLine("Data inserted.");
    }
}

Go

Puoi scrivere i dati utilizzando Mutation. Un Mutation è un container per operazioni di mutazione. Un Mutation rappresenta una sequenza di inserti, aggiornamenti, eliminazioni e così via, che può essere applicata a livello atomico a diverse righe e tabelle in un database Spanner.

Usa Mutation.InsertOrUpdate() per creare una mutazione INSERT_OR_UPDATE, che aggiunge una nuova riga o aggiorna i valori della colonna se la riga esiste già. In alternativa, usa il metodo Mutation.Insert() per creare una mutazione INSERT, che aggiunge una nuova riga.

Client.Apply() applica le mutazioni a livello atomico a un database.

Questo codice mostra come scrivere i dati:

import (
	"context"
	"io"

	"cloud.google.com/go/spanner"
)

func write(w io.Writer, db string) error {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, db)
	if err != nil {
		return err
	}
	defer client.Close()

	singerColumns := []string{"SingerId", "FirstName", "LastName"}
	albumColumns := []string{"SingerId", "AlbumId", "AlbumTitle"}
	m := []*spanner.Mutation{
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{1, "Marc", "Richards"}),
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{2, "Catalina", "Smith"}),
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{3, "Alice", "Trentor"}),
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{4, "Lea", "Martin"}),
		spanner.InsertOrUpdate("Singers", singerColumns, []interface{}{5, "David", "Lomond"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{1, 1, "Total Junk"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{1, 2, "Go, Go, Go"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{2, 1, "Green"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{2, 2, "Forever Hold Your Peace"}),
		spanner.InsertOrUpdate("Albums", albumColumns, []interface{}{2, 3, "Terrified"}),
	}
	_, err = client.Apply(ctx, m)
	return err
}

Java

Puoi scrivere i dati utilizzando un oggetto Mutation. Un oggetto Mutation è un contenitore per le operazioni di mutazione. Un Mutation rappresenta una sequenza di inserti, aggiornamenti ed eliminazioni che Spanner applica a livello atomico a diverse righe e tabelle in un database Spanner.

Il metodo newInsertBuilder() nella classe Mutation crea una mutazione INSERT, che inserisce una nuova riga in una tabella. Se la riga esiste già, la scrittura non riesce. In alternativa, puoi utilizzare il metodo newInsertOrUpdateBuilder per creare una modifica INSERT_OR_UPDATE, che aggiorna i valori della colonna se la riga esiste già.

Il metodo write() nella classe DatabaseClient scrive le mutazioni. Tutte le mutazioni in un singolo lotto vengono applicate a livello atomico.

Questo codice mostra come scrivere i dati:

static final List<Singer> SINGERS =
    Arrays.asList(
        new Singer(1, "Marc", "Richards"),
        new Singer(2, "Catalina", "Smith"),
        new Singer(3, "Alice", "Trentor"),
        new Singer(4, "Lea", "Martin"),
        new Singer(5, "David", "Lomond"));

static final List<Album> ALBUMS =
    Arrays.asList(
        new Album(1, 1, "Total Junk"),
        new Album(1, 2, "Go, Go, Go"),
        new Album(2, 1, "Green"),
        new Album(2, 2, "Forever Hold Your Peace"),
        new Album(2, 3, "Terrified"));
static void writeExampleData(DatabaseClient dbClient) {
  List<Mutation> mutations = new ArrayList<>();
  for (Singer singer : SINGERS) {
    mutations.add(
        Mutation.newInsertBuilder("Singers")
            .set("SingerId")
            .to(singer.singerId)
            .set("FirstName")
            .to(singer.firstName)
            .set("LastName")
            .to(singer.lastName)
            .build());
  }
  for (Album album : ALBUMS) {
    mutations.add(
        Mutation.newInsertBuilder("Albums")
            .set("SingerId")
            .to(album.singerId)
            .set("AlbumId")
            .to(album.albumId)
            .set("AlbumTitle")
            .to(album.albumTitle)
            .build());
  }
  dbClient.write(mutations);
}

Node.js

Puoi scrivere i dati utilizzando un oggetto Table. Il metodo Table.insert() aggiunge nuove righe alla tabella. Tutti gli inserti in un singolo batch vengono applicati a livello atomico.

Questo codice mostra come scrivere i dati:

// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';

// Creates a client
const spanner = new Spanner({
  projectId: projectId,
});

// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);

// Instantiate Spanner table objects
const singersTable = database.table('Singers');
const albumsTable = database.table('Albums');

// Inserts rows into the Singers table
// Note: Cloud Spanner interprets Node.js numbers as FLOAT64s, so
// they must be converted to strings before being inserted as INT64s
try {
  await singersTable.insert([
    {SingerId: '1', FirstName: 'Marc', LastName: 'Richards'},
    {SingerId: '2', FirstName: 'Catalina', LastName: 'Smith'},
    {SingerId: '3', FirstName: 'Alice', LastName: 'Trentor'},
    {SingerId: '4', FirstName: 'Lea', LastName: 'Martin'},
    {SingerId: '5', FirstName: 'David', LastName: 'Lomond'},
  ]);

  await albumsTable.insert([
    {SingerId: '1', AlbumId: '1', AlbumTitle: 'Total Junk'},
    {SingerId: '1', AlbumId: '2', AlbumTitle: 'Go, Go, Go'},
    {SingerId: '2', AlbumId: '1', AlbumTitle: 'Green'},
    {SingerId: '2', AlbumId: '2', AlbumTitle: 'Forever Hold your Peace'},
    {SingerId: '2', AlbumId: '3', AlbumTitle: 'Terrified'},
  ]);

  console.log('Inserted data.');
} catch (err) {
  console.error('ERROR:', err);
} finally {
  await database.close();
}

PHP

Puoi scrivere i dati utilizzando il metodo Database::insertBatch. insertBatch aggiunge nuove righe a una tabella. Tutti gli inserti in un singolo batch vengono applicati a livello atomico.

Questo codice mostra come scrivere i dati:

use Google\Cloud\Spanner\SpannerClient;

/**
 * Inserts sample data into the given database.
 *
 * The database and table must already exist and can be created using
 * `create_database`.
 * Example:
 * ```
 * insert_data($instanceId, $databaseId);
 * ```
 *
 * @param string $instanceId The Spanner instance ID.
 * @param string $databaseId The Spanner database ID.
 */
function insert_data(string $instanceId, string $databaseId): void
{
    $spanner = new SpannerClient();
    $instance = $spanner->instance($instanceId);
    $database = $instance->database($databaseId);

    $operation = $database->transaction(['singleUse' => true])
        ->insertBatch('Singers', [
            ['SingerId' => 1, 'FirstName' => 'Marc', 'LastName' => 'Richards'],
            ['SingerId' => 2, 'FirstName' => 'Catalina', 'LastName' => 'Smith'],
            ['SingerId' => 3, 'FirstName' => 'Alice', 'LastName' => 'Trentor'],
            ['SingerId' => 4, 'FirstName' => 'Lea', 'LastName' => 'Martin'],
            ['SingerId' => 5, 'FirstName' => 'David', 'LastName' => 'Lomond'],
        ])
        ->insertBatch('Albums', [
            ['SingerId' => 1, 'AlbumId' => 1, 'AlbumTitle' => 'Total Junk'],
            ['SingerId' => 1, 'AlbumId' => 2, 'AlbumTitle' => 'Go, Go, Go'],
            ['SingerId' => 2, 'AlbumId' => 1, 'AlbumTitle' => 'Green'],
            ['SingerId' => 2, 'AlbumId' => 2, 'AlbumTitle' => 'Forever Hold Your Peace'],
            ['SingerId' => 2, 'AlbumId' => 3, 'AlbumTitle' => 'Terrified']
        ])
        ->commit();

    print('Inserted data.' . PHP_EOL);
}

Python

Puoi scrivere i dati utilizzando un oggetto Batch. Un oggetto Batch è un container per le operazioni di mutazione. Una mutazione rappresenta una sequenza di inserti, aggiornamenti, eliminazioni e così via che può essere applicata a livello atomico a diverse righe e tabelle in un database Spanner.

Il metodo insert() nella classe Batch viene utilizzato per aggiungere una o più mutazioni di inserimento al batch. Tutte le mutazioni in un singolo batch vengono applicate a livello atomico.

Questo codice mostra come scrivere i dati:

def insert_data(instance_id, database_id):
    """Inserts sample data into the given database.

    The database and table must already exist and can be created using
    `create_database`.
    """
    spanner_client = spanner.Client()
    instance = spanner_client.instance(instance_id)
    database = instance.database(database_id)

    with database.batch() as batch:
        batch.insert(
            table="Singers",
            columns=("SingerId", "FirstName", "LastName"),
            values=[
                (1, "Marc", "Richards"),
                (2, "Catalina", "Smith"),
                (3, "Alice", "Trentor"),
                (4, "Lea", "Martin"),
                (5, "David", "Lomond"),
            ],
        )

        batch.insert(
            table="Albums",
            columns=("SingerId", "AlbumId", "AlbumTitle"),
            values=[
                (1, 1, "Total Junk"),
                (1, 2, "Go, Go, Go"),
                (2, 1, "Green"),
                (2, 2, "Forever Hold Your Peace"),
                (2, 3, "Terrified"),
            ],
        )

    print("Inserted data.")

Ruby

Puoi scrivere i dati utilizzando un oggetto Client. Il metodo Client#commit crea ed esegue il commit di una transazione per le scritture eseguite a livello atomico in un unico momento logico su colonne, righe e tabelle di un database.

Questo codice mostra come scrivere i dati:

# project_id  = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new project: project_id
client  = spanner.client instance_id, database_id

client.commit do |c|
  c.insert "Singers", [
    { SingerId: 1, FirstName: "Marc",     LastName: "Richards" },
    { SingerId: 2, FirstName: "Catalina", LastName: "Smith"    },
    { SingerId: 3, FirstName: "Alice",    LastName: "Trentor"  },
    { SingerId: 4, FirstName: "Lea",      LastName: "Martin"   },
    { SingerId: 5, FirstName: "David",    LastName: "Lomond"   }
  ]
  c.insert "Albums", [
    { SingerId: 1, AlbumId: 1, AlbumTitle: "Total Junk" },
    { SingerId: 1, AlbumId: 2, AlbumTitle: "Go, Go, Go" },
    { SingerId: 2, AlbumId: 1, AlbumTitle: "Green" },
    { SingerId: 2, AlbumId: 2, AlbumTitle: "Forever Hold Your Peace" },
    { SingerId: 2, AlbumId: 3, AlbumTitle: "Terrified" }
  ]
end

puts "Inserted data"

Aggiornare le righe in una tabella

Supponiamo che le vendite di Albums(1, 1) siano inferiori al previsto. Di conseguenza, vuoi spostare 200.000 $dal budget di marketing di Albums(2, 2) a Albums(1, 1), ma solo se il denaro è disponibile nel budget di Albums(2, 2).

Poiché devi leggere i dati nelle tabelle per determinare se scrivere nuovi valori, devi utilizzare una transazione di lettura e scrittura per eseguire le letture e le scritture a livello atomico.

C++

Utilizza la funzione Transaction() per eseguire una transazione per un client.

Ecco il codice per eseguire la transazione:

void ReadWriteTransaction(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  using ::google::cloud::StatusOr;

  // A helper to read a single album MarketingBudget.
  auto get_current_budget =
      [](spanner::Client client, spanner::Transaction txn,
         std::int64_t singer_id,
         std::int64_t album_id) -> StatusOr<std::int64_t> {
    auto key = spanner::KeySet().AddKey(spanner::MakeKey(singer_id, album_id));
    auto rows = client.Read(std::move(txn), "Albums", std::move(key),
                            {"MarketingBudget"});
    using RowType = std::tuple<std::int64_t>;
    auto row = spanner::GetSingularRow(spanner::StreamOf<RowType>(rows));
    if (!row) return std::move(row).status();
    return std::get<0>(*std::move(row));
  };

  auto commit = client.Commit(
      [&client, &get_current_budget](
          spanner::Transaction const& txn) -> StatusOr<spanner::Mutations> {
        auto b1 = get_current_budget(client, txn, 1, 1);
        if (!b1) return std::move(b1).status();
        auto b2 = get_current_budget(client, txn, 2, 2);
        if (!b2) return std::move(b2).status();
        std::int64_t transfer_amount = 200000;

        return spanner::Mutations{
            spanner::UpdateMutationBuilder(
                "Albums", {"SingerId", "AlbumId", "MarketingBudget"})
                .EmplaceRow(1, 1, *b1 + transfer_amount)
                .EmplaceRow(2, 2, *b2 - transfer_amount)
                .Build()};
      });

  if (!commit) throw std::move(commit).status();
  std::cout << "Transfer was successful [spanner_read_write_transaction]\n";
}

C#

Per .NET Standard 2.0 (o .NET 4.5) e versioni successive, puoi utilizzare TransactionScope() di .NET Framework per eseguire una transazione. Per tutte le versioni supportate di .NET, puoi creare una transazione impostando il risultato di SpannerConnection.BeginTransactionAsync come proprietà Transaction di SpannerCommand.

Ecco i due modi per eseguire la transazione:

.NET Standard 2.0

using Google.Cloud.Spanner.Data;
using System;
using System.Threading.Tasks;
using System.Transactions;

public class ReadWriteWithTransactionAsyncSample
{
    public async Task<int> ReadWriteWithTransactionAsync(string projectId, string instanceId, string databaseId)
    {
        // This sample transfers 200,000 from the MarketingBudget
        // field of the second Album to the first Album. Make sure to run
        // the Add Column and Write Data To New Column samples first,
        // in that order.

        string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";

        using TransactionScope scope = new TransactionScope(TransactionScopeAsyncFlowOption.Enabled);
        decimal transferAmount = 200000;
        decimal secondBudget = 0;
        decimal firstBudget = 0;

        using var connection = new SpannerConnection(connectionString);
        using var cmdLookup1 = connection.CreateSelectCommand("SELECT * FROM Albums WHERE SingerId = 2 AND AlbumId = 2");

        using (var reader = await cmdLookup1.ExecuteReaderAsync())
        {
            while (await reader.ReadAsync())
            {
                // Read the second album's budget.
                secondBudget = reader.GetFieldValue<decimal>("MarketingBudget");
                // Confirm second Album's budget is sufficient and
                // if not raise an exception. Raising an exception
                // will automatically roll back the transaction.
                if (secondBudget < transferAmount)
                {
                    throw new Exception($"The second album's budget {secondBudget} is less than the amount to transfer.");
                }
            }
        }

        // Read the first album's budget.
        using var cmdLookup2 = connection.CreateSelectCommand("SELECT * FROM Albums WHERE SingerId = 1 and AlbumId = 1");
        using (var reader = await cmdLookup2.ExecuteReaderAsync())
        {
            while (await reader.ReadAsync())
            {
                firstBudget = reader.GetFieldValue<decimal>("MarketingBudget");
            }
        }

        // Specify update command parameters.
        using var cmdUpdate = connection.CreateUpdateCommand("Albums", new SpannerParameterCollection
        {
            { "SingerId", SpannerDbType.Int64 },
            { "AlbumId", SpannerDbType.Int64 },
            { "MarketingBudget", SpannerDbType.Int64 },
        });

        // Update second album to remove the transfer amount.
        secondBudget -= transferAmount;
        cmdUpdate.Parameters["SingerId"].Value = 2;
        cmdUpdate.Parameters["AlbumId"].Value = 2;
        cmdUpdate.Parameters["MarketingBudget"].Value = secondBudget;
        var rowCount = await cmdUpdate.ExecuteNonQueryAsync();

        // Update first album to add the transfer amount.
        firstBudget += transferAmount;
        cmdUpdate.Parameters["SingerId"].Value = 1;
        cmdUpdate.Parameters["AlbumId"].Value = 1;
        cmdUpdate.Parameters["MarketingBudget"].Value = firstBudget;
        rowCount += await cmdUpdate.ExecuteNonQueryAsync();
        scope.Complete();
        Console.WriteLine("Transaction complete.");
        return rowCount;
    }
}

.NET Standard 1.5

using Google.Cloud.Spanner.Data;
using System;
using System.Threading.Tasks;

public class ReadWriteWithTransactionCoreAsyncSample
{
    public async Task<int> ReadWriteWithTransactionCoreAsync(string projectId, string instanceId, string databaseId)
    {
        // This sample transfers 200,000 from the MarketingBudget
        // field of the second Album to the first Album. Make sure to run
        // the Add Column and Write Data To New Column samples first,
        // in that order.
        string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";

        decimal transferAmount = 200000;
        decimal secondBudget = 0;
        decimal firstBudget = 0;

        using var connection = new SpannerConnection(connectionString);
        await connection.OpenAsync();

        using var transaction = await connection.BeginTransactionAsync();

        using var cmdLookup1 = connection.CreateSelectCommand("SELECT * FROM Albums WHERE SingerId = 2 AND AlbumId = 2");
        cmdLookup1.Transaction = transaction;

        using (var reader = await cmdLookup1.ExecuteReaderAsync())
        {
            while (await reader.ReadAsync())
            {
                // Read the second album's budget.
                secondBudget = reader.GetFieldValue<decimal>("MarketingBudget");
                // Confirm second Album's budget is sufficient and
                // if not raise an exception. Raising an exception
                // will automatically roll back the transaction.
                if (secondBudget < transferAmount)
                {
                    throw new Exception($"The second album's budget {secondBudget} contains less than the amount to transfer.");
                }
            }
        }
        // Read the first album's budget.
        using var cmdLookup2 = connection.CreateSelectCommand("SELECT * FROM Albums WHERE SingerId = 1 and AlbumId = 1");
        cmdLookup2.Transaction = transaction;
        using (var reader = await cmdLookup2.ExecuteReaderAsync())
        {
            while (await reader.ReadAsync())
            {
                firstBudget = reader.GetFieldValue<decimal>("MarketingBudget");
            }
        }

        // Specify update command parameters.
        using var cmdUpdate = connection.CreateUpdateCommand("Albums", new SpannerParameterCollection
        {
            { "SingerId", SpannerDbType.Int64 },
            { "AlbumId", SpannerDbType.Int64 },
            { "MarketingBudget", SpannerDbType.Int64 },
        });
        cmdUpdate.Transaction = transaction;

        // Update second album to remove the transfer amount.
        secondBudget -= transferAmount;
        cmdUpdate.Parameters["SingerId"].Value = 2;
        cmdUpdate.Parameters["AlbumId"].Value = 2;
        cmdUpdate.Parameters["MarketingBudget"].Value = secondBudget;
        var rowCount = await cmdUpdate.ExecuteNonQueryAsync();

        // Update first album to add the transfer amount.
        firstBudget += transferAmount;
        cmdUpdate.Parameters["SingerId"].Value = 1;
        cmdUpdate.Parameters["AlbumId"].Value = 1;
        cmdUpdate.Parameters["MarketingBudget"].Value = firstBudget;
        rowCount += await cmdUpdate.ExecuteNonQueryAsync();

        await transaction.CommitAsync();
        Console.WriteLine("Transaction complete.");
        return rowCount;
    }
}

Go

Utilizza il tipo ReadWriteTransaction per eseguire una parte del lavoro nel contesto di una transazione di lettura e scrittura. Client.ReadWriteTransaction() restituisce un oggetto ReadWriteTransaction.

Nell'esempio viene utilizzato ReadWriteTransaction.ReadRow() per recuperare una riga di dati.

L'esempio utilizza anche ReadWriteTransaction.BufferWrite(), che aggiunge un elenco di mutazioni al set di aggiornamenti che verranno applicati quando viene eseguito il commit della transazione.

L'esempio utilizza anche il tipo Key, che rappresenta una chiave di riga in una tabella o un indice Spanner.

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/spanner"
)

func writeWithTransaction(w io.Writer, db string) error {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, db)
	if err != nil {
		return err
	}
	defer client.Close()

	_, err = client.ReadWriteTransaction(ctx, func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
		getBudget := func(key spanner.Key) (int64, error) {
			row, err := txn.ReadRow(ctx, "Albums", key, []string{"MarketingBudget"})
			if err != nil {
				return 0, err
			}
			var budget int64
			if err := row.Column(0, &budget); err != nil {
				return 0, err
			}
			return budget, nil
		}
		album2Budget, err := getBudget(spanner.Key{2, 2})
		if err != nil {
			return err
		}
		const transferAmt = 200000
		if album2Budget >= transferAmt {
			album1Budget, err := getBudget(spanner.Key{1, 1})
			if err != nil {
				return err
			}
			album1Budget += transferAmt
			album2Budget -= transferAmt
			cols := []string{"SingerId", "AlbumId", "MarketingBudget"}
			txn.BufferWrite([]*spanner.Mutation{
				spanner.Update("Albums", cols, []interface{}{1, 1, album1Budget}),
				spanner.Update("Albums", cols, []interface{}{2, 2, album2Budget}),
			})
			fmt.Fprintf(w, "Moved %d from Album2's MarketingBudget to Album1's.", transferAmt)
		}
		return nil
	})
	return err
}

Java

Utilizza l'interfaccia TransactionRunner per eseguire una parte del lavoro nel contesto di una transazione di lettura-scrittura. Questa interfaccia contiene il metodo run(), che viene utilizzato per eseguire una transazione di lettura e scrittura, con nuovi tentativi, se necessari. Il metodo readWriteTransaction della classe DatabaseClient restituisce un oggetto TransactionRunner per l'esecuzione di una singola transazione logica.

La classe TransactionRunner.TransactionCallable contiene un metodo run() per eseguire un singolo tentativo di transazione. run() prende un oggetto TransactionContext, che è un contesto per una transazione.

Nell'esempio viene utilizzata la classe Struct, utile per archiviare i risultati delle chiamate readRow(). L'esempio utilizza anche la classe Key, che rappresenta una chiave di riga in una tabella o un indice Spanner.

Ecco il codice per eseguire la transazione:

static void writeWithTransaction(DatabaseClient dbClient) {
  dbClient
      .readWriteTransaction()
      .run(transaction -> {
        // Transfer marketing budget from one album to another. We do it in a transaction to
        // ensure that the transfer is atomic.
        Struct row =
            transaction.readRow("Albums", Key.of(2, 2), Arrays.asList("MarketingBudget"));
        long album2Budget = row.getLong(0);
        // Transaction will only be committed if this condition still holds at the time of
        // commit. Otherwise it will be aborted and the callable will be rerun by the
        // client library.
        long transfer = 200000;
        if (album2Budget >= transfer) {
          long album1Budget =
              transaction
                  .readRow("Albums", Key.of(1, 1), Arrays.asList("MarketingBudget"))
                  .getLong(0);
          album1Budget += transfer;
          album2Budget -= transfer;
          transaction.buffer(
              Mutation.newUpdateBuilder("Albums")
                  .set("SingerId")
                  .to(1)
                  .set("AlbumId")
                  .to(1)
                  .set("MarketingBudget")
                  .to(album1Budget)
                  .build());
          transaction.buffer(
              Mutation.newUpdateBuilder("Albums")
                  .set("SingerId")
                  .to(2)
                  .set("AlbumId")
                  .to(2)
                  .set("MarketingBudget")
                  .to(album2Budget)
                  .build());
        }
        return null;
      });
}

Node.js

Utilizza Database.runTransaction() per eseguire una transazione.

Ecco il codice per eseguire la transazione:

// This sample transfers 200,000 from the MarketingBudget field
// of the second Album to the first Album, as long as the second
// Album has enough money in its budget. Make sure to run the
// addColumn and updateData samples first (in that order).

// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';

// Creates a client
const spanner = new Spanner({
  projectId: projectId,
});

// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);

const transferAmount = 200000;

database.runTransaction(async (err, transaction) => {
  if (err) {
    console.error(err);
    return;
  }
  let firstBudget, secondBudget;
  const queryOne = {
    columns: ['MarketingBudget'],
    keys: [[2, 2]], // SingerId: 2, AlbumId: 2
  };

  const queryTwo = {
    columns: ['MarketingBudget'],
    keys: [[1, 1]], // SingerId: 1, AlbumId: 1
  };

  Promise.all([
    // Reads the second album's budget
    transaction.read('Albums', queryOne).then(results => {
      // Gets second album's budget
      const rows = results[0].map(row => row.toJSON());
      secondBudget = rows[0].MarketingBudget;
      console.log(`The second album's marketing budget: ${secondBudget}`);

      // Makes sure the second album's budget is large enough
      if (secondBudget < transferAmount) {
        throw new Error(
          `The second album's budget (${secondBudget}) is less than the transfer amount (${transferAmount}).`
        );
      }
    }),

    // Reads the first album's budget
    transaction.read('Albums', queryTwo).then(results => {
      // Gets first album's budget
      const rows = results[0].map(row => row.toJSON());
      firstBudget = rows[0].MarketingBudget;
      console.log(`The first album's marketing budget: ${firstBudget}`);
    }),
  ])
    .then(() => {
      console.log(firstBudget, secondBudget);
      // Transfers the budgets between the albums
      firstBudget += transferAmount;
      secondBudget -= transferAmount;

      console.log(firstBudget, secondBudget);

      // Updates the database
      // Note: Cloud Spanner interprets Node.js numbers as FLOAT64s, so they
      // must be converted (back) to strings before being inserted as INT64s.
      transaction.update('Albums', [
        {
          SingerId: '1',
          AlbumId: '1',
          MarketingBudget: firstBudget.toString(),
        },
        {
          SingerId: '2',
          AlbumId: '2',
          MarketingBudget: secondBudget.toString(),
        },
      ]);
    })
    .then(() => {
      // Commits the transaction and send the changes to the database
      return transaction.commit();
    })
    .then(() => {
      console.log(
        `Successfully executed read-write transaction to transfer ${transferAmount} from Album 2 to Album 1.`
      );
    })
    .catch(err => {
      console.error('ERROR:', err);
    })
    .then(() => {
      transaction.end();
      // Closes the database when finished
      return database.close();
    });
});

PHP

Utilizza Database::runTransaction per eseguire una transazione.

Ecco il codice per eseguire la transazione:

use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Transaction;
use UnexpectedValueException;

/**
 * Performs a read-write transaction to update two sample records in the
 * database.
 *
 * This will transfer 200,000 from the `MarketingBudget` field for the second
 * Album to the first Album. If the `MarketingBudget` for the second Album is
 * too low, it will raise an exception.
 *
 * Before running this sample, you will need to run the `update_data` sample
 * to populate the fields.
 * Example:
 * ```
 * read_write_transaction($instanceId, $databaseId);
 * ```
 *
 * @param string $instanceId The Spanner instance ID.
 * @param string $databaseId The Spanner database ID.
 */
function read_write_transaction(string $instanceId, string $databaseId): void
{
    $spanner = new SpannerClient();
    $instance = $spanner->instance($instanceId);
    $database = $instance->database($databaseId);

    $database->runTransaction(function (Transaction $t) use ($spanner) {
        $transferAmount = 200000;

        // Read the second album's budget.
        $secondAlbumKey = [2, 2];
        $secondAlbumKeySet = $spanner->keySet(['keys' => [$secondAlbumKey]]);
        $secondAlbumResult = $t->read(
            'Albums',
            $secondAlbumKeySet,
            ['MarketingBudget'],
            ['limit' => 1]
        );

        $firstRow = $secondAlbumResult->rows()->current();
        $secondAlbumBudget = $firstRow['MarketingBudget'];
        if ($secondAlbumBudget < $transferAmount) {
            // Throwing an exception will automatically roll back the transaction.
            throw new UnexpectedValueException(
                'The second album\'s budget is lower than the transfer amount: ' . $transferAmount
            );
        }

        $firstAlbumKey = [1, 1];
        $firstAlbumKeySet = $spanner->keySet(['keys' => [$firstAlbumKey]]);
        $firstAlbumResult = $t->read(
            'Albums',
            $firstAlbumKeySet,
            ['MarketingBudget'],
            ['limit' => 1]
        );

        // Read the first album's budget.
        $firstRow = $firstAlbumResult->rows()->current();
        $firstAlbumBudget = $firstRow['MarketingBudget'];

        // Update the budgets.
        $secondAlbumBudget -= $transferAmount;
        $firstAlbumBudget += $transferAmount;
        printf('Setting first album\'s budget to %s and the second album\'s ' .
            'budget to %s.' . PHP_EOL, $firstAlbumBudget, $secondAlbumBudget);

        // Update the rows.
        $t->updateBatch('Albums', [
            ['SingerId' => 1, 'AlbumId' => 1, 'MarketingBudget' => $firstAlbumBudget],
            ['SingerId' => 2, 'AlbumId' => 2, 'MarketingBudget' => $secondAlbumBudget],
        ]);

        // Commit the transaction!
        $t->commit();

        print('Transaction complete.' . PHP_EOL);
    });
}

Python

Utilizza il metodo run_in_transaction() della classe Database per eseguire una transazione.

Ecco il codice per eseguire la transazione:

def read_write_transaction(instance_id, database_id):
    """Performs a read-write transaction to update two sample records in the
    database.

    This will transfer 200,000 from the `MarketingBudget` field for the second
    Album to the first Album. If the `MarketingBudget` is too low, it will
    raise an exception.

    Before running this sample, you will need to run the `update_data` sample
    to populate the fields.
    """
    spanner_client = spanner.Client()
    instance = spanner_client.instance(instance_id)
    database = instance.database(database_id)

    def update_albums(transaction):
        # Read the second album budget.
        second_album_keyset = spanner.KeySet(keys=[(2, 2)])
        second_album_result = transaction.read(
            table="Albums",
            columns=("MarketingBudget",),
            keyset=second_album_keyset,
            limit=1,
        )
        second_album_row = list(second_album_result)[0]
        second_album_budget = second_album_row[0]

        transfer_amount = 200000

        if second_album_budget < transfer_amount:
            # Raising an exception will automatically roll back the
            # transaction.
            raise ValueError("The second album doesn't have enough funds to transfer")

        # Read the first album's budget.
        first_album_keyset = spanner.KeySet(keys=[(1, 1)])
        first_album_result = transaction.read(
            table="Albums",
            columns=("MarketingBudget",),
            keyset=first_album_keyset,
            limit=1,
        )
        first_album_row = list(first_album_result)[0]
        first_album_budget = first_album_row[0]

        # Update the budgets.
        second_album_budget -= transfer_amount
        first_album_budget += transfer_amount
        print(
            "Setting first album's budget to {} and the second album's "
            "budget to {}.".format(first_album_budget, second_album_budget)
        )

        # Update the rows.
        transaction.update(
            table="Albums",
            columns=("SingerId", "AlbumId", "MarketingBudget"),
            values=[(1, 1, first_album_budget), (2, 2, second_album_budget)],
        )

    database.run_in_transaction(update_albums)

    print("Transaction complete.")

Ruby

Utilizza il metodo transaction della classe Client per eseguire una transazione.

Ecco il codice per eseguire la transazione:

# project_id  = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"

require "google/cloud/spanner"

spanner         = Google::Cloud::Spanner.new project: project_id
client          = spanner.client instance_id, database_id
transfer_amount = 200_000

client.transaction do |transaction|
  first_album  = transaction.read("Albums", [:MarketingBudget], keys: [[1, 1]]).rows.first
  second_album = transaction.read("Albums", [:MarketingBudget], keys: [[2, 2]]).rows.first

  raise "The second album does not have enough funds to transfer" if second_album[:MarketingBudget] < transfer_amount

  new_first_album_budget  = first_album[:MarketingBudget] + transfer_amount
  new_second_album_budget = second_album[:MarketingBudget] - transfer_amount

  transaction.update "Albums", [
    { SingerId: 1, AlbumId: 1, MarketingBudget: new_first_album_budget  },
    { SingerId: 2, AlbumId: 2, MarketingBudget: new_second_album_budget }
  ]
end

puts "Transaction complete"

Eliminare righe in una tabella

Ogni libreria client offre diversi modi per eliminare le righe:

• Eliminare tutte le righe di una tabella.
• Elimina una singola riga specificando i valori della colonna chiave per la riga.
• Elimina un gruppo di righe creando un intervallo di chiavi.
• Elimina le righe in una tabella con interleaving eliminando le righe padre, se la tabella con interleaving include ON DELETE CASCADE nella definizione dello schema.

Nota: il limite di mutazioni per commit è 80.000. Ogni indice secondario in una tabella è una modifica aggiuntiva per riga. Ad esempio, in una tabella con un indice secondario, puoi eliminare fino a 40.000 righe in un commit. Per eliminare una grande quantità di dati, utilizza DML partizionato. Il codice DML partizionato gestisce i limiti delle transazioni ed è ottimizzato per gestire le eliminazioni su larga scala.

C++

Elimina le righe utilizzando la funzione DeleteMutationBuilder() per un client.

Questo codice mostra come eliminare i dati:

void DeleteData(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;

  // Delete the albums with key (2,1) and (2,3).
  auto delete_albums = spanner::DeleteMutationBuilder(
                           "Albums", spanner::KeySet()
                                         .AddKey(spanner::MakeKey(2, 1))
                                         .AddKey(spanner::MakeKey(2, 3)))
                           .Build();

  // Delete some singers using the keys in the range [3, 5]
  auto delete_singers_range =
      spanner::DeleteMutationBuilder(
          "Singers", spanner::KeySet().AddRange(spanner::MakeKeyBoundClosed(3),
                                                spanner::MakeKeyBoundOpen(5)))
          .Build();

  // Deletes remaining rows from the Singers table and the Albums table, because
  // the Albums table is defined with ON DELETE CASCADE.
  auto delete_singers_all =
      spanner::MakeDeleteMutation("Singers", spanner::KeySet::All());

  auto commit_result = client.Commit(spanner::Mutations{
      delete_albums, delete_singers_range, delete_singers_all});
  if (!commit_result) throw std::move(commit_result).status();
  std::cout << "Delete was successful [spanner_delete_data]\n";
}

C#

Elimina le righe utilizzando il metodo connection.CreateDeleteCommand(), che crea un nuovo SpannerCommand per eliminare le righe. Il metodo SpannerCommand.ExecuteNonQueryAsync() elimina le righe dalla tabella.

Questo esempio elimina singolarmente le righe della tabella Singers. Le righe nella tabella Albums vengono eliminate perché la tabella Albums ha un interleaving nella tabella Singers ed è definita con ON DELETE CASCADE.

using Google.Cloud.Spanner.Data;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

public class DeleteDataAsyncSample
{
    public class Album
    {
        public int SingerId { get; set; }
        public int AlbumId { get; set; }
        public string AlbumTitle { get; set; }
    }

    public async Task<int> DeleteDataAsync(string projectId, string instanceId, string databaseId)
    {
        string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";

        var albums = new List<Album>
        {
            new Album { SingerId = 2, AlbumId = 1, AlbumTitle = "Green" },
            new Album { SingerId = 2, AlbumId = 3, AlbumTitle = "Terrified" },
        };

        int rowCount = 0;
        using (var connection = new SpannerConnection(connectionString))
        {
            await connection.OpenAsync();

            // Delete individual rows from the Albums table.
            await Task.WhenAll(albums.Select(async album =>
            {
                var cmd = connection.CreateDeleteCommand("Albums", new SpannerParameterCollection
                {
                    { "SingerId", SpannerDbType.Int64, album.SingerId },
                    { "AlbumId", SpannerDbType.Int64, album.AlbumId }
                });
                rowCount += await cmd.ExecuteNonQueryAsync();
            }));
            Console.WriteLine("Deleted individual rows in Albums.");

            // Delete a range of rows from the Singers table where the column key is >=3 and <5.
            var cmd = connection.CreateDmlCommand("DELETE FROM Singers WHERE SingerId >= 3 AND SingerId < 5");
            rowCount += await cmd.ExecuteNonQueryAsync();
            Console.WriteLine($"{rowCount} row(s) deleted from Singers.");

            // Delete remaining Singers rows, which will also delete the remaining
            // Albums rows since it was defined with ON DELETE CASCADE.
            cmd = connection.CreateDmlCommand("DELETE FROM Singers WHERE true");
            rowCount += await cmd.ExecuteNonQueryAsync();
            Console.WriteLine($"{rowCount} row(s) deleted from Singers.");
        }
        return rowCount;
    }
}

Go

Eliminare le righe utilizzando una Mutation. Usa il metodo Mutation.Delete() per creare una mutazione DELETE, che elimina una riga. Il metodo Client.Apply() applica le mutazioni a livello atomico al database.

Questo esempio elimina singolarmente le righe nella tabella Albums e poi tutte le righe nella tabella Singers utilizzando un KeyRange.

import (
	"context"
	"io"

	"cloud.google.com/go/spanner"
)

func delete(w io.Writer, db string) error {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, db)
	if err != nil {
		return err
	}
	defer client.Close()

	m := []*spanner.Mutation{
		// spanner.Key can be used to delete a specific set of rows.
		// Delete the Albums with the key values (2,1) and (2,3).
		spanner.Delete("Albums", spanner.Key{2, 1}),
		spanner.Delete("Albums", spanner.Key{2, 3}),
		// spanner.KeyRange can be used to delete rows with a key in a specific range.
		// Delete a range of rows where the column key is >=3 and <5
		spanner.Delete("Singers", spanner.KeyRange{Start: spanner.Key{3}, End: spanner.Key{5}, Kind: spanner.ClosedOpen}),
		// spanner.AllKeys can be used to delete all the rows in a table.
		// Delete remaining Singers rows, which will also delete the remaining Albums rows since it was
		// defined with ON DELETE CASCADE.
		spanner.Delete("Singers", spanner.AllKeys()),
	}
	_, err = client.Apply(ctx, m)
	return err
}

Java

Eliminare le righe utilizzando il metodo Mutation.delete().

In questo esempio viene utilizzato il metodo KeySet.all() per eliminare tutte le righe nella tabella Albums. Dopo aver eliminato le righe nella tabella Albums, nell'esempio vengono eliminate singolarmente le righe della tabella Singers utilizzando le chiavi create con il metodo KeySet.singleKey().

static void deleteExampleData(DatabaseClient dbClient) {
  List<Mutation> mutations = new ArrayList<>();

  // KeySet.Builder can be used to delete a specific set of rows.
  // Delete the Albums with the key values (2,1) and (2,3).
  mutations.add(
      Mutation.delete(
          "Albums", KeySet.newBuilder().addKey(Key.of(2, 1)).addKey(Key.of(2, 3)).build()));

  // KeyRange can be used to delete rows with a key in a specific range.
  // Delete a range of rows where the column key is >=3 and <5
  mutations.add(
      Mutation.delete("Singers", KeySet.range(KeyRange.closedOpen(Key.of(3), Key.of(5)))));

  // KeySet.all() can be used to delete all the rows in a table.
  // Delete remaining Singers rows, which will also delete the remaining Albums rows since it was
  // defined with ON DELETE CASCADE.
  mutations.add(Mutation.delete("Singers", KeySet.all()));

  dbClient.write(mutations);
  System.out.printf("Records deleted.\n");
}

Node.js

Eliminare le righe utilizzando il metodo table.deleteRows().

In questo esempio viene utilizzato il metodo table.deleteRows() per eliminare tutte le righe dalla tabella Singers. Le righe nella tabella Albums vengono eliminate perché la tabella Albums è con interleaving nella tabella Singers ed è definita con ON DELETE CASCADE.

// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';

// Creates a client
const spanner = new Spanner({
  projectId: projectId,
});

// Gets a reference to a Cloud Spanner instance and database
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);

// Instantiate Spanner table object
const albumsTable = database.table('Albums');

// Deletes individual rows from the Albums table.
try {
  const keys = [
    [2, 1],
    [2, 3],
  ];
  await albumsTable.deleteRows(keys);
  console.log('Deleted individual rows in Albums.');
} catch (err) {
  console.error('ERROR:', err);
}

// Delete a range of rows where the column key is >=3 and <5
database.runTransaction(async (err, transaction) => {
  if (err) {
    console.error(err);
    return;
  }
  try {
    const [rowCount] = await transaction.runUpdate({
      sql: 'DELETE FROM Singers WHERE SingerId >= 3 AND SingerId < 5',
    });
    console.log(`${rowCount} records deleted from Singers.`);
  } catch (err) {
    console.error('ERROR:', err);
  }

  // Deletes remaining rows from the Singers table and the Albums table,
  // because Albums table is defined with ON DELETE CASCADE.
  try {
    // The WHERE clause is required for DELETE statements to prevent
    // accidentally deleting all rows in a table.
    // https://cloud.google.com/spanner/docs/dml-syntax#where_clause
    const [rowCount] = await transaction.runUpdate({
      sql: 'DELETE FROM Singers WHERE true',
    });
    console.log(`${rowCount} records deleted from Singers.`);
    await transaction.commit();
  } catch (err) {
    console.error('ERROR:', err);
  } finally {
    // Close the database when finished.
    await database.close();
  }
});

PHP

Eliminare le righe utilizzando Database::delete() method. La pagina Metodo Database::delete() include un esempio.

Python

Eliminare le righe utilizzando il metodo Batch.delete().

Questo esempio elimina tutte le righe nelle tabelle Albums e Singers singolarmente utilizzando un oggetto KeySet.

def delete_data(instance_id, database_id):
    """Deletes sample data from the given database.

    The database, table, and data must already exist and can be created using
    `create_database` and `insert_data`.
    """
    spanner_client = spanner.Client()
    instance = spanner_client.instance(instance_id)
    database = instance.database(database_id)

    # Delete individual rows
    albums_to_delete = spanner.KeySet(keys=[[2, 1], [2, 3]])

    # Delete a range of rows where the column key is >=3 and <5
    singers_range = spanner.KeyRange(start_closed=[3], end_open=[5])
    singers_to_delete = spanner.KeySet(ranges=[singers_range])

    # Delete remaining Singers rows, which will also delete the remaining
    # Albums rows because Albums was defined with ON DELETE CASCADE
    remaining_singers = spanner.KeySet(all_=True)

    with database.batch() as batch:
        batch.delete("Albums", albums_to_delete)
        batch.delete("Singers", singers_to_delete)
        batch.delete("Singers", remaining_singers)

    print("Deleted data.")

Ruby

Eliminare le righe utilizzando il metodo Client#delete. La pagina Client#delete include un esempio.

# project_id  = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new project: project_id
client  = spanner.client instance_id, database_id

# Delete individual rows
client.delete "Albums", [[2, 1], [2, 3]]

# Delete a range of rows where the column key is >=3 and <5
key_range = client.range 3, 5, exclude_end: true
client.delete "Singers", key_range

# Delete remaining Singers rows, which will also delete the remaining
# Albums rows because Albums was defined with ON DELETE CASCADE
client.delete "Singers"