Blue-Green Deployment

Your e-commerce site processes millions in revenue daily. A simple database migration that takes your site offline for 10 minutes costs thousands in lost sales and damages customer trust.

Traditional migration approaches require downtime: stop the application, run migrations, restart with new code. Zero-downtime migrations eliminate this disruption using careful planning and deployment strategies that keep your application running throughout database updates.

The Zero-Downtime Challenge

Standard EF Core migrations assume a simple deployment model:

1. Stop application
2. Run dotnet ef database update
3. Deploy new application code
4. Start application

This works for small applications but creates unacceptable downtime for production systems. The challenge is that database schema changes often require corresponding application code changes, creating a chicken-and-egg problem.

Backward-Compatible Migration Patterns

Zero-downtime migrations require backward compatibility: the database must work with both old and new application versions during the transition.

Adding New Tables

Adding new tables is always safe:

public partial class AddOrderHistoryTable : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.CreateTable(
            name: "OrderHistory",
            columns: table => new
            {
                Id = table.Column<int>(nullable: false)
                    .Annotation("SqlServer:Identity", …