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# Postgre SQL

PostgreSQL 是一个开源的关系型数据库，它已经变得越来越流行，你可以使用 Postgre SQL 来作为 CAP 消息的持久化。

## 配置

要使用 PostgreSQL 存储，你需要从 NuGet 安装以下扩展包：

    Install-Package DotNetCore.CAP.PostgreSql

然后，你可以在 `Startup.cs` 的 `ConfigureServices` 方法中添加基于内存的配置项。

    public void ConfigureServices(IServiceCollection services)
    {
        // ...

        services.AddCap(x =>
        {
            x.UsePostgreSql(opt=>{
                //PostgreSqlOptions
            });
            // x.UseXXX ...
        });
    }

#### PostgreSqlOptions

NAME | DESCRIPTION | TYPE | DEFAULT
--- | --- | --- | ---
Schema | 数据库架构 | string | cap
ConnectionString | 数据库连接字符串 | string |

## Publish with transaction

### ADO.NET with transaction

    private readonly ICapPublisher _capBus;

    using (var connection = new NpgsqlConnection("ConnectionString"))
    {
        using (var transaction = connection.BeginTransaction(_capBus, autoCommit: false))
        {
            //your business code
            connection.Execute("insert into test(name) values('test')",
                transaction: (IDbTransaction)transaction.DbTransaction);

            _capBus.Publish("sample.rabbitmq.mysql", DateTime.Now);

            transaction.Commit();
        }
    }

### EntityFramework with transaction

    private readonly ICapPublisher _capBus;

    using (var trans = dbContext.Database.BeginTransaction(_capBus, autoCommit: false))
    {
        dbContext.Persons.Add(new Person() { Name = "ef.transaction" });

        _capBus.Publish("sample.rabbitmq.mysql", DateTime.Now);

        dbContext.SaveChanges();
        trans.Commit();
    }