c# - Entity Framework 6 - Timing queries

Question

I am using Entity Framework 6 and it's awesome database interceptor features to log queries which are being sent from application the database. However, I am struggling to time those queries, I have a long running query which returns hundred of thousands to millions of rows so it takes around 6 to 15 seconds depending on the amount of data this query is going to return. Entity framework is returning a SqlDataReader because of which I cannot get the exact time it takes to get the result. I want to know the complete execution time from the time query was sent to the time last row was read. Is there a way I can do it.

Answer 1

Here is the logger I usually use for EF.

public class EFLoggerForTesting : IDbCommandInterceptor
{
    static readonly ConcurrentDictionary<DbCommand, DateTime> m_StartTime = new ConcurrentDictionary<DbCommand, DateTime>();

    public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        Log(command, interceptionContext);
    }

    public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        Log(command, interceptionContext);
    }

    public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        Log(command, interceptionContext);
    }

    private static void Log<T>(DbCommand command, DbCommandInterceptionContext<T> interceptionContext)
    {
        DateTime startTime;
        TimeSpan duration;


        if (m_StartTime.TryRemove(command, out startTime))
        {
            duration = DateTime.Now - startTime;
        }
        else
            duration = TimeSpan.Zero;

        var requestId =-1;
        string message;

        var parameters = new StringBuilder();
        foreach (DbParameter param in command.Parameters)
        {
            parameters.AppendLine(param.ParameterName + " " + param.DbType + " = " + param.Value);
        }

        if (interceptionContext.Exception == null)
        {
            message = string.Format("Database call took {0} sec. RequestId {1} 
Command:
{2}", duration.TotalSeconds.ToString("N3"), requestId, parameters.ToString() + command.CommandText);
        }
        else
        {
            message = string.Format("EF Database call failed after {0} sec. RequestId {1} 
Command:
{2}
Error:{3} ", duration.TotalSeconds.ToString("N3"), requestId, parameters.ToString() + command.CommandText, interceptionContext.Exception);
        }

        Debug.WriteLine(message);
    }


    public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        OnStart(command);
    }

    public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        OnStart(command);
    }

    public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        OnStart(command);
    }
    private static void OnStart(DbCommand command)
    {
        m_StartTime.TryAdd(command, DateTime.Now);
    }
}

Unfortunately the documentation is non-existent so I don't know if this will work for your scenario.