Overview

A storage provider tells Wallaby what to capture and how to turn raw row changes back into your types. The core Wallaby package is provider-agnostic, with it owning the replication slot, publication, checkpointing, backfills, and sink delivery, while a provider contributes the capture model and the materialization back into your CLR types.

Two providers are available:

• EF Core: Captures the tables behind your DbContext's entity mappings; transforms receive a leased DbContext.
• Marten: Captures Marten document tables and rehydrates each change through the store's own serializer; transforms receive a leased IQuerySession.

Combining providers

Both providers can be registered in one Wallaby instance sharing a single replication slot/publication/checkpoint. Global commit ordering is preserved across EF tables and Marten document tables:

cdc.UseEntityFrameworkCore<AppDbContext>()
   .UseMarten()
   .AddMeilisearchSink("meili", m => { /* ... */ })
   .WithMappings(sink =>
   {
       sink.Map<Product>().UsingTransform(/* DbContext transform */);
       sink.Map<Order>().UsingTransform(/* IQuerySession transform */);
   });

Slot/publication names, batching, backfill versions, and sinks are all configured once and shared between providers.

How mappings resolve to a provider

Each mapped entity type resolves to the provider that models it:

• If exactly one registered provider models the type, that provider wins — nothing to configure.
• If both model it, a provider-typed UsingTransform overload breaks the tie: each provider's overloads pin the mapping to that provider.
• Pin explicitly with Map<T>().FromProvider(...) (provider names: "EntityFrameworkCore", "Marten").
• Remaining ambiguity, or a FromProvider pin that contradicts the transform's provider will fail fast at startup with guidance.
• A type mapped under several sinks resolves once — all its mappings share one table, so a pin on any of them decides for all (conflicting pins fail fast).

Enrichment sessions

Transforms are handed the session type native to their mapping's provider, a DbContext for EF Core mappings, an IQuerySession for Marten mappings. Tenant-scoped session leasing is likewise per provider — see multi-tenancy for EF Core and Marten.

External slots are provider-independent and can be declared alongside any combination of the above, or on their own in provision-only mode.