.NET Archives - Page 2 of 6

Select Multiple Properties using Linq - Fun C# Code #3

C#'s Linq is an simply amazing. However, as far as I know, there is no built-in ability to select multiple fields (of the same type) and return them, so here you go

ASP.NET Core - Optimisation Hacks

Google has developed a tool called PageSpeed. It highlighted couple of quick wins I could do to improve website's loading time. Website loading times are one of the most deceptive metrics to measure during development. Website development is frequently done on a local machine when download times are neligiable. It is only once the website

ConcurrentDictionary - Get Snapshot and Clear - Fun C# Code #2

Recently, I was asked to write a 'real-time' calculator and the output value was to be stored in Redis. For legacy reasons, it also had to be stored in the database though, only the latest value had to be kept. As the calculator was spewing values, they were stored in a ConcurrentDictionary. When the timer

Fun C# Code #1 - Infinite Delay (until cancelled)

I came across this code when reading 'Concurrency in C# Cookbook' by Stephen Cleary. Did you know you can have an infinite Task.Delay without loops?

await Task.Delay(Timeout.InfiniteTimeSpan, ...)

1	await Task.Delay(Timeout.InfiniteTimeSpan, ...)

Obviously, there isn't much point in spinning a task that litterally will do nothing. You can use a CancellationToken to cancel the task.

using var cts = new CancellationTokenSource();
await Task.Delay(Timeout.InfiniteTimeSpan, cts.Token);

1 2	using var cts = new CancellationTokenSource(); await Task.Delay(Timeout.InfiniteTimeSpan, cts.Token);

No point. It's just one

Dealing with SQL Server Space - Part 1

Recently, I have been building a large database for the new House-Buddy project. The site uses a huge collection of data to identify the sweet-spots around a particular location. The site is hosted on a shared hosting which in theory had unlimited DB storage, but after they noticed the size of the database has grown

Adding Quartz to your ASP.NET Core

This is a ready made example of how to add a scheduled job to your ASP.NET core web application:

    public class YourJob : IJob
    {

        public static async void Start() {
            IScheduler scheduler = await StdSchedulerFactory.GetDefaultScheduler();
            await scheduler.Start();

            IJobDetail job = JobBuilder.Create<YourJob>().Build();

            ITrigger trigger = TriggerBuilder.Create()
                .WithDailyTimeIntervalSchedule(s =>s.WithIntervalInSeconds(10))
                .StartNow()
                .Build();

            await scheduler.ScheduleJob(job, trigger);
        }

        Task IJob.Execute(IJobExecutionContext context) {
            return Task.Run(() => {
                Program.Counter++;
            });
        }
    }

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public class YourJob : IJob

{

public static async void Start() {

IScheduler scheduler = await StdSchedulerFactory.GetDefaultScheduler();

await scheduler.Start();

IJobDetail job = JobBuilder.Create<YourJob>().Build();

ITrigger trigger = TriggerBuilder.Create()

.WithDailyTimeIntervalSchedule(s =>s.WithIntervalInSeconds(10))

.StartNow()

.Build();

await scheduler.ScheduleJob(job, trigger);

}

Task IJob.Execute(IJobExecutionContext context) {

return Task.Run(() => {

Program.Counter++;

});

}

In your Program.cs

        public static int Counter = 0;

        public static void Main(string[] args)
        {
            var host = BuildWebHost(args); 

            YourJob.Start();
            host.Run();
        }

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public static int Counter = 0;

public static void Main(string[] args)

{

var host = BuildWebHost(args);

YourJob.Start();

host.Run();

}

How to regain space after dropping columns in SQL Server

I hit an annoying issue today. I wanted to regain space after I dropped several columns in a table. When I run the famous query from StackOverflow:

SELECT 
    t.NAME AS TableName,
    s.Name AS SchemaName,
    p.rows AS RowCounts,
    SUM(a.total_pages) * 8 AS TotalSpaceKB, 
    CAST(ROUND(((SUM(a.total_pages) * 8) / 1024.00 / 1024.00), 2) AS NUMERIC(36, 2)) AS TotalSpaceMB,
    SUM(a.used_pages) * 8 AS UsedSpaceKB, 
    CAST(ROUND(((SUM(a.used_pages) * 8) / 1024.00/ 1024.00), 2) AS NUMERIC(36, 2)) AS UsedSpaceMB, 
    (SUM(a.total_pages) - SUM(a.used_pages)) * 8 AS UnusedSpaceKB,
    CAST(ROUND(((SUM(a.total_pages) - SUM(a.used_pages)) * 8) / 1024.00, 2) AS NUMERIC(36, 2)) AS UnusedSpaceMB
FROM 
    sys.tables t
INNER JOIN      
    sys.indexes i ON t.OBJECT_ID = i.object_id
INNER JOIN 
    sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id
INNER JOIN 
    sys.allocation_units a ON p.partition_id = a.container_id
LEFT OUTER JOIN 
    sys.schemas s ON t.schema_id = s.schema_id
WHERE 
    t.NAME NOT LIKE 'dt%' 
    AND t.is_ms_shipped = 0
    AND i.OBJECT_ID > 255 
GROUP BY 
    t.Name, s.Name, p.Rows
ORDER BY 
    t.Name

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SELECT

t.NAME AS TableName,

s.Name AS SchemaName,

p.rows AS RowCounts,

SUM(a.total_pages) * 8 AS TotalSpaceKB,

CAST(ROUND(((SUM(a.total_pages) * 8) / 1024.00 / 1024.00), 2) AS NUMERIC(36, 2)) AS TotalSpaceMB,

SUM(a.used_pages) * 8 AS UsedSpaceKB,

CAST(ROUND(((SUM(a.used_pages) * 8) / 1024.00/ 1024.00), 2) AS NUMERIC(36, 2)) AS UsedSpaceMB,

(SUM(a.total_pages) - SUM(a.used_pages)) * 8 AS UnusedSpaceKB,

CAST(ROUND(((SUM(a.total_pages) - SUM(a.used_pages)) * 8) / 1024.00, 2) AS NUMERIC(36, 2)) AS UnusedSpaceMB

FROM

sys.tables t

INNER JOIN

sys.indexes i ON t.OBJECT_ID = i.object_id

INNER JOIN

sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id

INNER JOIN

sys.allocation_units a ON p.partition_id = a.container_id

LEFT OUTER JOIN

sys.schemas s ON t.schema_id = s.schema_id

WHERE

t.NAME NOT LIKE 'dt%'

AND t.is_ms_shipped = 0

AND i.OBJECT_ID > 255

GROUP BY

t.Name, s.Name, p.Rows

ORDER BY

t.Name

I got a set of numbers which were the same before and after the removal has

DBCC CLEANTABLE('YOUR_DB', 'SCHEMA.TABLE');

1	DBCC CLEANTABLE('YOUR_DB', 'SCHEMA.TABLE');

There is, however, a potential issue with this approach if

Transaction log is full due to LOG_BACKUP

Yesterday, when I was building a large DB from scratch I got an error saying:

Transaction Log for 'Database' is full due to LOG_BACKUP

1	Transaction Log for 'Database' is full due to LOG_BACKUP

Running this simple query solved the issue:

ALTER DATABASE MyDB SET RECOVERY SIMPLE;

1	ALTER DATABASE MyDB SET RECOVERY SIMPLE;

The ALTER TABLE statement conflicted with the FOREIGN KEY constrain

I've been trying to apply a new migration and I was getting the following error: The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK_dbo.Parent_dbo.Childs_ChildId". The conflict occurred in database "parents_db", table "dbo.Childs", column 'ChildId'. In my case, the table contained data. Therefore, either you have to assign a default value, set it as

MediaElement Not Firing Events

Today, we encountered quite an interesting problem. MediaElement wasn't firing events. Using simple speech synthesis on Windows 8.1 using the speech synthesiser we tried:

using(SpeechSynthesizer synthesizer = new SpeechSynthesizer())
{
    SpeechSynthesisStream stream = await synthesizer.SynthesizeTextToStreamAsync("How are you feeling today?");
    MediaElement mediaElement = new MediaElement();
    mediaElement.IsMuted = false;
    mediaElement.SetSource(stream, stream.ContentType);
    mediaElement.MediaEnded += (a, b) => { System.Diagnostics.Debug.WriteLine("Steam has eneded."); };
    mediaElement.Play();
}

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using(SpeechSynthesizer synthesizer = new SpeechSynthesizer())

{

SpeechSynthesisStream stream = await synthesizer.SynthesizeTextToStreamAsync("How are you feeling today?");

MediaElement mediaElement = new MediaElement();

mediaElement.IsMuted = false;

mediaElement.SetSource(stream, stream.ContentType);

mediaElement.MediaEnded += (a, b) => { System.Diagnostics.Debug.WriteLine("Steam has eneded."); };

mediaElement.Play();

}

None of the variations worked. The speech worked just the event wasn't getting fired. After a bit of digging it turned out that in order to fire events MediaElement must

Category: .NET

Select Multiple Properties using Linq - Fun C# Code #3

ASP.NET Core - Optimisation Hacks

ConcurrentDictionary - Get Snapshot and Clear - Fun C# Code #2

Fun C# Code #1 - Infinite Delay (until cancelled)

Dealing with SQL Server Space - Part 1

Adding Quartz to your ASP.NET Core

How to regain space after dropping columns in SQL Server

Transaction log is full due to LOG_BACKUP

The ALTER TABLE statement conflicted with the FOREIGN KEY constrain

MediaElement Not Firing Events

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