Event Store Configuration

Specifying the Schema

The database schema name for the event store tables is by default, the same schema as the document store itself. The event storage can be explicitly moved to a separate schema as shown below:

var store = DocumentStore.For(opts =>
{
    opts.Connection("some connection string");

    opts.Events.DatabaseSchemaName = "events";
});

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Stream Identity

The Event Store in Marten can identify and index streams either as Guids (System.Guid) or strings (System.String). This is reflected in the overloads of IEventStore such as IEventStore.StartStream, IEventStore.Append and IEventStore.AggregateStream that accept either string or Guid as the stream identifier.

Configuration of the stream identity is done through StoreOptions.Events.StreamIdentity. If not set, Marten defaults to StreamIdentity.AsGuid. The identity is configured once per store, whereby different stream identity types cannot be mixed. The following sample demonstrates configuring streams to be identified as strings.

var store = DocumentStore.For(opts =>
{
    opts.Connection("some connection string");

    // Override the stream identity to use strings
    opts.Events.StreamIdentity = StreamIdentity.AsString;
});

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Stream identity effects the underlying database schema of the Event Store related tables. Namely, using string identities configures stream_id in the mt_events table to be varchar, whereas uuid would be used for GUIDs. The same applies to the id column in mt_streams table.

Multi-Tenancy

The event storage can opt into conjoined multi-tenancy with this syntax:

var store = DocumentStore.For(opts =>
{
    opts.Connection("some connection string");

    // And that's all it takes, the events are now multi-tenanted
    opts.Events.TenancyStyle = TenancyStyle.Conjoined;
});

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By default, if you try to define projection with a single tenancy, Marten will throw an exception at runtime informing you about the mismatch.

You can enable global projections for conjoined tenancy.

opts.Events.EnableGlobalProjectionsForConjoinedTenancy = true;

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WARNING

If you enable global projections for conjoined tenancy, Marten won't validate potential tenancy mismatch and won't throw an exception for that case.