Handling Multiple Concurrent Updates in C# with Dapper - advanced patterns with Transactions
I've been struggling with this for a few days now and could really use some help. I'm relatively new to this, so bear with me. I'm working with an scenario when trying to handle multiple concurrent updates to the same database record using Dapper. My application is built on .NET 6 and uses SQL Server. I implemented transactions to ensure that updates are atomic, but I'm noticing that sometimes the updates are not being reflected correctly, leading to stale data being served to users. Here’s a simplified version of what my code looks like: ```csharp using (var connection = new SqlConnection(connectionString)) { await connection.OpenAsync(); using (var transaction = connection.BeginTransaction()) { var command = new CommandDefinition( "UPDATE Users SET LastUpdated = @LastUpdated WHERE Id = @Id", new { LastUpdated = DateTime.UtcNow, Id = userId }, transaction: transaction); await connection.ExecuteAsync(command); transaction.Commit(); } } ``` The scenario arises when two or more users try to update the same user record at the same time. I’ve also tried implementing optimistic concurrency by adding a `RowVersion` column, but I still see cases where the updates conflict and the last write wins, resulting in lost updates. I’ve set the `RowVersion` column in the SQL table like this: ```sql ALTER TABLE Users ADD RowVersionColumn ROWVERSION; ``` And modified the update statement: ```csharp var command = new CommandDefinition( "UPDATE Users SET LastUpdated = @LastUpdated WHERE Id = @Id AND RowVersionColumn = @RowVersion", new { LastUpdated = DateTime.UtcNow, Id = userId, RowVersion = rowVersion }, transaction: transaction); ``` However, this still does not seem to prevent the lost updates. The behavior message I receive when the `RowVersion` check fails is: ``` SqlException: The row was not found or the update affected zero rows. ``` I would appreciate any guidance on best practices for handling concurrent updates in Dapper, especially in terms of transaction management or alternative strategies I might consider. Are there any patterns or techniques that could guide to avoid this scenario altogether? This is part of a larger API I'm building. My development environment is Linux. What's the best practice here? The stack includes C# and several other technologies. I'd be grateful for any help.