Pluralsight & Packt Author, Director, CTO, Software Architect, Team leader, Tutor, Speaker, Software Developer. I like to make fast scalable things using C# and SQL Server.
Wednesday 31 December 2008
Blackberry 8800 video encoding - How to
The download link is very hard to find, so its here
Use these settings:
Output container: AVI
Video Codec: DIVX
Audio Codec: mp3
Encoder: MEncoder
Video settings
Size: 320:176
Aspect: 16:9
Frame/sec: 12.5 (pal) 14.985 (NTSC)
Audio settings
Sampling freq: 22050
Channels: 2
Bitrate: 64
Audio stream: default
Enjoy!
Friday 19 December 2008
A generic singleton - Part 2
Well, it isn't really singleton - since you can't control
T
, there can be as many T
instances as you like.The code does check for non-public constructors, which is good. However, this is a check which is only performed at execution time - there's no compile-time check, which is a strike against it. It also relies on having enough access to call the non-public constructor, which adds some limitations.
In addition, it doesn't prohibit internal constructors - so you can end up with non-singletons.
There is an excellent article on singletons at http://www.yoda.arachsys.com/csharp/singleton.html
Here are two proper implementations:
public sealed class Singleton
{
static readonly Singleton instance = new Singleton();
// Explicit static constructor to tell C# compiler
// not to mark type as beforefieldinit
static Singleton()
{
}
Singleton()
{
}
public static Singleton Instance
{
get { return instance; }
}
}
Or simply:
public class Singleton
{
private static Singleton _instance = new Singleton();
private Singleton() {}
public static Singleton Instance { get { return _instance; }}
}
Both of these classes removes the need for locking, as a static constructor is thread safe.
Surprising SQL speed increase - Part 2
Part 1 is availble below
More generally speaking, you should never use a function on the LEFT side of a WHERE clause in a query. If you do, SQL won't use an index--it has to evaluate the function for every row of the table. The goal is to make sure that your where clause is "Sargable"
Some other examples:
Bad: Select ... WHERE isNull(FullName,'') = 'Ed Jones'
Fixed: Select ... WHERE ((FullName = 'Ed Jones') OR (FullName IS NULL))Bad: Select ... WHERE SUBSTRING(DealerName,4) = 'Ford'
Fixed: Select ... WHERE DealerName Like 'Ford%'Bad: Select ... WHERE DateDiff(mm,OrderDate,GetDate()) >= 30
Fixed: Select ... WHERE OrderDate < DateAdd(mm,-30,GetDate())
Bad: Select ... WHERE Year(OrderDate) = 2003
Fixed: Select ... WHERE OrderDate >= '2003-1-1' AND OrderDate < '2004-1-1'