PartitionedDmlSample.cs

// Copyright 2021 Google Inc. All Rights Reserved.
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using Google.Cloud.EntityFrameworkCore.Spanner.Extensions;
using Google.Cloud.EntityFrameworkCore.Spanner.Samples.SampleModel;
using Google.Cloud.EntityFrameworkCore.Spanner.Storage;
using System;
using System.Threading.Tasks;

/// <summary>
/// Cloud Spanner can execute DML statements in transactional mode (the default) or
/// using Partitioned DML. Partitioned DML is not directly supported in Entity Framework Core,
/// but the underlying SpannerConnection can be extracted from a DbContext and can be
/// used to execute Partitioned DML.
/// 
/// See https://cloud.google.com/spanner/docs/dml-partitioned for more information
/// on Partitioned DML.
/// 
/// Run from the command line with `dotnet run PartitionedDmlSample`
/// </summary>
public static class PartitionedDmlSample
{
    public static async Task Run(string connectionString)
    {
        // Create a DbContext and insert a couple of example Singer rows.
        using var context = new SpannerSampleDbContext(connectionString);
        await Setup(context);
        
        // Now delete all Singer rows using Partitioned DML.
        // For this we first need to get the underlying SpannerConnection.
        var connection = context.Database.GetSpannerConnection();
        // Execute a Partitioned DML statement using the connection.
        using var cmd = connection.CreateDmlCommand("DELETE FROM Singers WHERE TRUE");
        var deleted = await cmd.ExecutePartitionedUpdateAsync();

        Console.WriteLine($"Deleted {deleted} Singer records using Partitioned DML");
    }
    
    private static async Task Setup(SpannerSampleDbContext context)
    {
        await context.Singers.AddRangeAsync(
            new Singer
            {
                SingerId = Guid.NewGuid(),
                FirstName = "Alice",
                LastName = "Henderson",
                BirthDate = new SpannerDate(1983, 10, 19),
            },
            new Singer
            {
                SingerId = Guid.NewGuid(),
                FirstName = "Peter",
                LastName = "Allison",
                BirthDate = new SpannerDate(2000, 5, 2),
            },
            new Singer
            {
                SingerId = Guid.NewGuid(),
                FirstName = "Mike",
                LastName = "Nicholson",
                BirthDate = new SpannerDate(1976, 8, 31),
            });
        await context.SaveChangesAsync();
    }
}