You can also provide your own LinqToDb.DataOptions object for a more advanced configuration.
Assuming a setup with a custom NpgsqlDataSource:
NpgsqlDataSource dataSource = new NpgsqlDataSourceBuilder(_myConnectionString).Build();
DataOptions dataOptions = new DataOptions()
.UseDataProvider(DataConnection.GetDataProvider(ProviderName.PostgreSQL, dataSource.ConnectionString) ?? throw new Exception("Could not get data provider"))
.UseProvider(ProviderName.PostgreSQL)
.UseConnectionFactory((opt) => dataSource.CreateConnection());
var host = new HostBuilder()
.ConfigureServices((context, services) => {
services.AddAkka("my-system-name", (builder, provider) =>
{
builder.WithSqlPersistence(dataOptions);
});
});
If dataOptions are provided, you must supply enough information for linq2db to connect to the database.
This includes setting the connection string and provider name again, if necessary for your use case.
Please consult the Linq2Db documentation for more details on configuring a valid DataOptions object.
Note that MappingSchema and RetryPolicy will always be overridden by Akka.Persistence.Sql.
Health Checks
Starting with Akka.Persistence.Sql v1.5.51 or later, you can add health checks for your persistence plugins. Akka.Persistence.Sql supports two types of health checks that integrate with Microsoft.Extensions.Diagnostics.HealthChecks and can be used with ASP.NET Core health check endpoints.
Standard Health Checks
Standard health checks monitor the persistence plugins themselves and verify that journals and snapshot stores are properly initialized and accessible.
To configure standard health checks, use the journalBuilder and snapshotBuilder parameters with the .WithHealthCheck() method:
Standard health checks are tagged with akka, persistence, and either journal or snapshot-store for filtering and organization purposes.
Connectivity Health Checks (Akka.Persistence.Sql.Hosting v1.5.X+)
Connectivity health checks proactively verify database connectivity regardless of recent operation activity. This helps detect database outages during idle periods when the standard health checks might not catch issues.
Using Akka.Hosting 1.5.55.1 or later (Simplified API):
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.
DDL Scripts for Database Schema Management
Pre-generated DDL scripts are available in docs/ddl/ for creating Akka.Persistence.Sql tables through your own migrations instead of relying on automatic table creation at runtime.
Directory Structure:
docs/ddl/default/ - For new deployments using table-mapping = default
docs/ddl/compat/ - For migration from legacy plugins (uses provider-specific table mappings)
Each directory contains SQL scripts for each supported provider (sqlserver, postgresql, mysql, sqlite):
journal.sql - Event journal table
journal-tags.sql - Tag table for TagMode.TagTable
snapshot.sql - Snapshot store table
metadata.sql - Metadata table for delete-compatibility-mode
When to use DDL scripts:
When using Entity Framework Core or FluentMigrator for schema management
When you need explicit control over database schema versioning
When auto-initialization is disabled (auto-initialize = false)
See the DDL documentation for detailed usage instructions and examples.
Tuning Akka.Persistence.Query for Low-Latency Projections
Default polling intervals cause 500-1200ms projection latency. For low-latency CQRS, tune BOTH settings together:
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.