Why should you care?

ShopNest checkout transaction must not span SMS OTP wait — long locks block other shoppers buying same SKU.

See it live — copy this example

Paste into a .NET project with EF Core packages, then run with LocalDB/SQL Server (dotnet ef / dotnet run).

var strategy = _context.Database.CreateExecutionStrategy();
await strategy.ExecuteAsync(async () =>
{
    await using var tx = await _context.Database.BeginTransactionAsync(IsolationLevel.ReadCommitted);
    var product = await _context.Products.FindAsync(id);
    product!.StockQty -= qty;
    _context.Orders.Add(order);
    await _context.SaveChangesAsync();
    await tx.CommitAsync();
});

What happened?

• ExecutionStrategy retries transient failures on Azure SQL.
• ReadCommitted default balances consistency and locks.
• Transaction wraps only DB work — not payment HTTP.

Practice next

1. Keep transaction scope minimal — reserve stock then commit before payment.
2. Use ReadCommitted unless phantom reads require Serializable.
3. Enable retry strategy for cloud SQL.
4. Measure lock duration with extended events during sale test.
5. Split reserve inventory and finalize order into two short transactions with saga.

Remember

Short transactions reduce lock time. Match isolation level to business need. Retry only transient DB errors with idempotent steps.

ShopNest checkout locks

Team shrinks transaction to stock reserve + order insert only; payment capture follows after commit.

Outcome: Hot SKU contention drops; fewer deadlock retries.