README.md

Akka.Persistence.Sql

A Cross-SQL-DB Engine Akka.Persistence plugin with broad database compatibility thanks to Linq2Db.

This is a port of the amazing akka-persistence-jdbc package from Scala, with a few improvements based on C# as well as our choice of data library.

Please read the documentation carefully. Some features may have specific use case and have trade-offs (namely, compatibility modes).

If you're migrating from legacy Akka.Persistence.Sql.Common based plugins, you can read the migration guide documentation, the migration tutorial, and watch the migration tutorial video.

Table Of Content

• Akka.Persistence.Sql
• Getting Started
  • The Easy Way, Using Akka.Hosting
  • The Classic Way, Using HOCON
  • Supported Database Providers
    • Tested Database Providers
    • Supported By Linq2Db But Untested In Akka.Persistence
• Sql.Common Compatibility modes
• Migration Guide
  • Migrating Using Compatibility Mode
    • Akka.Hosting Migration
    • HOCON Migration
  • Upgrading to Tag Table (Optional)
  • Enable WriterUuid Anti-Corruption Layer Feature (Recommended)
• Migration Tutorial
• Features/Architecture
  • Currently Implemented
  • Incomplete
• Performance Benchmarks
• Configuration
  • Journal
  • Snapshot Store
• Building this solution
  • Conventions
  • Release Notes, Version Numbers, Etc

Getting Started

The Easy Way, Using Akka.Hosting

Assuming a MS SQL Server 2019 setup:

var host = new HostBuilder()
    .ConfigureServices((context, services) => {
        services.AddAkka("my-system-name", (builder, provider) =>
        {
            builder.WithSqlPersistence(
                connectionString: _myConnectionString,
                providerName: ProviderName.SqlServer2019)
        });
    })

The Classic Way, Using HOCON

These are the minimum HOCON configuration you need to start using Akka.Persistence.Sql:

akka.persistence {
    journal {
        plugin = "akka.persistence.journal.sql"
        sql {
            class = "Akka.Persistence.Sql.Journal.SqlWriteJournal, Akka.Persistence.Sql"
            connection-string = "{database-connection-string}"
            provider-name = "{provider-name}"
        }
    }
    query.journal.sql {
        class = "Akka.Persistence.Sql.Query.SqlReadJournalProvider, Akka.Persistence.Sql"
        connection-string = "{database-connection-string}"
        provider-name = "{provider-name}"
    }
    snapshot-store {
        plugin = "akka.persistence.snapshot-store.sql"
        sql {
            class = "Akka.Persistence.Sql.Snapshot.SqlSnapshotStore, Akka.Persistence.Sql"
            connection-string = "{database-connection-string}"
            provider-name = "{provider-name}"
        }
    }
}

• database-connection-string: The proper connection string to your database of choice.
• provider-name: A string constant defining the database type to connect to, valid values are defined inside LinqToDB.ProviderName static class. Refer to the Members of LinqToDb.ProviderName for included providers.

Note: For best performance, one should use the most specific provider name possible. i.e. LinqToDB.ProviderName.SqlServer2012 instead of LinqToDB.ProviderName.SqlServer. Otherwise certain provider detections have to run more frequently which may impair performance slightly.

Supported Database Providers

Tested Database Providers

• Microsoft SQL Server
• MS SQLite
• System.Data.SQLite
• PostgreSQL using binary payload
• MySql

Supported By Linq2Db But Untested In Akka.Persistence

• Firebird
• Microsoft Access OleDB
• Microsoft Access ODBC
• IBM DB2
• Informix
• Oracle
• Sybase
• SAP HANA
• ClickHouse

Sql.Common Compatibility modes

• Delete Compatibility mode is available.
  • This mode will utilize a journal_metadata table containing the last sequence number
  • The main table delete is done the same way regardless of delete compatibility mode

Delete Compatibility mode is expensive.

• Normal Deletes involve first marking the deleted records as deleted, and then deleting them
  • Table compatibility mode adds an additional InsertOrUpdate and Delete
• This all happens in a transaction
  • In SQL Server this can cause issues because of page locks/etc.

Building this solution

To run the build script associated with this solution, execute the following:

Windows

c:\> build.cmd all

Linux / OS X

c:\> build.sh all

If you need any information on the supported commands, please execute the build.[cmd|sh] help command.

This build script is powered by FAKE; please see their API documentation should you need to make any changes to the build.fsx file.

Conventions

The attached build script will automatically do the following based on the conventions of the project names added to this project:

• Any project name ending with .Tests will automatically be treated as a XUnit2 project and will be included during the test stages of this build script;
• Any project name ending with .Tests will automatically be treated as a NBench project and will be included during the test stages of this build script; and
• Any project meeting neither of these conventions will be treated as a NuGet packaging target and its .nupkg file will automatically be placed in the bin\nuget folder upon running the build.[cmd|sh] all command.

Release Notes, Version Numbers, Etc

This project will automatically populate its release notes in all of its modules via the entries written inside RELEASE_NOTES.md and will automatically update the versions of all assemblies and NuGet packages via the metadata included inside Directory.Build.props.