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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Big Integer Event Sequences 8.x

By default, Marten's internal PostgreSQL functions (mt_quick_append_events) use standard 32-bit int types for event version numbers, sequence values, and return types. This works well for the vast majority of systems, but the int type has a maximum value of approximately 2.1 billion. For very high-volume event stores that may exceed this threshold, Marten provides an opt-in flag to switch these functions to use 64-bit bigint types instead:

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

    // Opt into bigint (64-bit) types for event sequences and versions
    // in the PostgreSQL event append functions
    opts.Events.EnableBigIntEvents = true;
});

When EnableBigIntEvents is true, the generated mt_quick_append_events function will declare its event_version, seq, and return_value variables as bigint instead of int, and return bigint[] instead of int[]. This prevents integer overflow errors when the global event sequence counter surpasses the ~2.1 billion limit of a 32-bit integer.

WARNING

Enabling this flag will cause Marten to regenerate the mt_quick_append_events function with different type signatures. This means a schema migration will be required when you first enable the flag. Marten's normal schema migration tooling will handle this automatically.

INFO

The EnableBigIntEvents flag is false by default in Marten 8.x for backward compatibility. Starting in Marten 9.0, this flag will default to true.