Job Store

The job store gives NBatch restart-from-failure capability. It tracks which chunks have been processed, so if a job crashes mid-way, the next run resumes where it left off instead of reprocessing everything.

The job store lives in a separate package — install it alongside the core:

dotnet add package NBatch.EntityFrameworkCore

---

Enabling the Job Store

var job = Job.CreateBuilder("csv-import")
    .UseJobStore(connectionString)                           // SQL Server (default)
    .AddStep("import", step => step
        .ReadFrom(reader)
        .WriteTo(writer)
        .WithChunkSize(100))
    .Build();

NBatch will automatically create the required tracking tables (nbatch.jobs, nbatch.steps, nbatch.step_exceptions) if they don’t exist.

---

Supported Providers

// SQL Server (default)
.UseJobStore(connStr, DatabaseProvider.SqlServer)

// PostgreSQL
.UseJobStore(connStr, DatabaseProvider.PostgreSql)

// SQLite
.UseJobStore(connStr, DatabaseProvider.Sqlite)

// MySQL / MariaDB (.NET 8 & 9 only)
.UseJobStore(connStr, DatabaseProvider.MySql)

The DatabaseProvider enum:

Value	Provider	Notes
SqlServer	Microsoft SQL Server	Default
PostgreSql	PostgreSQL via Npgsql
Sqlite	SQLite
MySql	MySQL / MariaDB via Pomelo	.NET 8 & .NET 9 only

Note: MySQL support uses the Pomelo.EntityFrameworkCore.MySql provider, which does not yet support .NET 10. NBatch will throw PlatformNotSupportedException if you select DatabaseProvider.MySql on .NET 10.

---

How It Works

1. When a job starts, NBatch creates a job record in the tracking database.
2. Before each chunk is processed, NBatch inserts a step record with the current chunk index.
3. After each chunk completes, the step record is updated with success/failure status.
4. On the next run, NBatch queries the last successful chunk index and resumes from there.

Restart Flow

Run 1:  Chunk 0 [ok] -> Chunk 1 [ok] -> Chunk 2 [ok] -> Chunk 3 [CRASH]
Run 2:  Resumes from Chunk 3 -> Chunk 3 [ok] -> Chunk 4 [ok] -> Done!

Schema

All tracking tables are created under the nbatch schema:

Table	Purpose
nbatch.jobs	One row per job — name, creation date, last run
nbatch.steps	One row per chunk processed — step index, items count, errors
nbatch.step_exceptions	One row per skipped exception — type, message, stack trace

---

With Dependency Injection

When using AddNBatch(), you can configure the job store inside the job builder:

builder.Services.AddNBatch(nbatch =>
{
    nbatch.AddJob("csv-import", job => job
        .UseJobStore(connStr, DatabaseProvider.PostgreSql)
        .AddStep("import", step => step
            .ReadFrom(reader)
            .WriteTo(writer)
            .WithChunkSize(100)))
        .RunEvery(TimeSpan.FromHours(1));
});

---

In-Memory Mode (Default)

If you don’t call .UseJobStore(...), NBatch uses an in-memory repository. This is lightweight and suitable for:

• One-off scripts
• Development and testing
• Jobs where reprocessing is acceptable

// No .UseJobStore() -- runs with in-memory tracking
var job = Job.CreateBuilder("simple-job")
    .AddStep("work", step => step
        .ReadFrom(reader)
        .WriteTo(writer))
    .Build();

Note: In-memory mode does not persist state between runs. Restarting the application will reprocess all data.

---

Resetting the Job Store

If you need to reprocess data from scratch, reset the tracking tables:

-- Clear all tracking data
DELETE FROM nbatch.step_exceptions;
DELETE FROM nbatch.steps;
DELETE FROM nbatch.jobs;

Or drop and recreate the database if using Docker:

docker compose down -v
docker compose up -d

---

Next: DI & Hosted Service →