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Event Store Providers

Each event store provider implements IEventStore with database-specific optimizations. SQL Server is the primary provider; cloud-native and document providers offer alternatives for specific deployment targets.

Before You Start​

SQL Server​

The primary event store provider with full transaction support.

Installation​

dotnet add package Excalibur.EventSourcing.SqlServer

Setup​

using Microsoft.Extensions.DependencyInjection;

// Combined registration (event store + snapshot store + outbox)
services.AddSqlServerEventSourcing(connectionString);

// Or with options
services.AddSqlServerEventSourcing(options =>
{
    options.ConnectionString = connectionString;
    options.EventStoreSchema = "es";
    options.SnapshotStoreSchema = "es";
    options.OutboxSchema = "es";
});

// Individual stores
services.AddSqlServerEventStore(connectionString);
services.AddSqlServerSnapshotStore(connectionString);
services.AddSqlServerOutboxStore(connectionString);

// With connection factory
services.AddSqlServerEventStore(() => new SqlConnection(connectionString));
services.AddSqlServerSnapshotStore(() => new SqlConnection(connectionString));
services.AddSqlServerOutboxStore(() => new SqlConnection(connectionString));

PostgreSQL​

Open-source alternative with Npgsql-based access.

Installation​

dotnet add package Excalibur.Data.Postgres

Setup​

// With connection string
services.AddPostgresEventStore(connectionString, options =>
{
    options.SchemaName = "public";  // Default
});

// With options
services.AddPostgresEventStore(connectionString, options =>
{
    options.SchemaName = "events";
    options.EventsTableName = "event_store_events";  // Default
});

// With connection factory (receives IServiceProvider)
services.AddPostgresEventStore(
    sp => new NpgsqlConnection(configuration.GetConnectionString("Postgres")),
    options =>
    {
        options.SchemaName = "events";
    });

MongoDB​

Document-based event store with flexible schema.

Installation​

dotnet add package Excalibur.Data.MongoDB

Setup​

// With connection string and database name
services.AddMongoDbEventStore(
    "mongodb://localhost:27017",
    "EventStore",
    options =>
    {
        options.CollectionName = "events";
    });

// With options callback
services.AddMongoDbEventStore(options =>
{
    options.ConnectionString = "mongodb://localhost:27017";
    options.DatabaseName = "EventStore";
    options.CollectionName = "events";
});

// With custom client factory (receives IServiceProvider)
services.AddMongoDbEventStore(
    sp => sp.GetRequiredService<IMongoClient>(),
    options =>
    {
        options.DatabaseName = "EventStore";
    });

Azure Cosmos DB​

Globally distributed event store with partition-based scaling.

Installation​

dotnet add package Excalibur.EventSourcing.CosmosDb

Setup​

// With options callback
services.AddCosmosDbEventStore(options =>
{
    options.EventsContainerName = "events";
    options.PartitionKeyPath = "/streamId";  // Default
});

// From configuration
services.AddCosmosDbEventStore(configuration);
services.AddCosmosDbEventStore(configuration, sectionName: "CosmosDbEventStore");

Partition Strategy​

Cosmos DB event stores partition by aggregate ID. Each aggregate's events are stored in a single logical partition for transactional consistency.

Amazon DynamoDB​

Serverless event store for AWS workloads.

Installation​

dotnet add package Excalibur.EventSourcing.DynamoDb

Setup​

// With options callback
services.AddDynamoDbEventStore(options =>
{
    options.EventsTableName = "Events";  // Default
});

// From configuration
services.AddDynamoDbEventStore(configuration);
services.AddDynamoDbEventStore(configuration, sectionName: "DynamoDbEventStore");

Key Schema​

DynamoDB event stores use the aggregate ID as the partition key and event version as the sort key, providing efficient sequential reads per aggregate.

Google Firestore​

Real-time event store for Google Cloud workloads.

Installation​

dotnet add package Excalibur.EventSourcing.Firestore

Setup​

// With options callback
services.AddFirestoreEventStore(options =>
{
    options.ProjectId = "my-gcp-project";
    options.EventsCollectionName = "events";
});

// From configuration
services.AddFirestoreEventStore(configuration);
services.AddFirestoreEventStore(configuration, sectionName: "FirestoreEventStore");

Collection Structure​

Firestore event stores use subcollections under aggregate documents, leveraging Firestore's hierarchical document model.

In-Memory (Testing)​

For unit and integration tests:

services.AddInMemoryEventStore();

Provider Comparison​

ProviderPackageTransaction SupportScaling Model
SQL ServerExcalibur.EventSourcing.SqlServerFull ACIDVertical + read replicas
PostgreSQLExcalibur.Data.PostgresFull ACIDVertical + read replicas
MongoDBExcalibur.Data.MongoDBDocument-levelSharding
Cosmos DBExcalibur.EventSourcing.CosmosDbPartition-scopedGlobal distribution
DynamoDBExcalibur.EventSourcing.DynamoDbItem-levelOn-demand / provisioned
FirestoreExcalibur.EventSourcing.FirestoreDocument-levelAutomatic
In-MemoryExcalibur.EventSourcing.InMemoryNoneSingle process

See Also​