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Does Foreign Key improve query performance?
... getting a 404 error. It's about having usable data. It's about not losing orders and financial data for reports for instance because of the incompetence of the developers. There is NO EXCUSE for not using foreign keys.
– HLGEM
Oct 19 '11 at 14:20
...
iPhone - Grand Central Dispatch main thread
... data on background queue -> signal main queue that message has arrived
etc etc
As to why you might want to dispatch to the main queue from the main queue... Well, you generally wouldn't although conceivably you might do it to schedule some work to do the next time around the run loop.
...
When do I use a dot, arrow, or double colon to refer to members of a class in C++?
...ect a. So, primarily, a is an object and b is a member (function/ variable etc) of a.
Arrow operator is used in indirect member selection scenarios.
print(a->b)
Here, we are accessing b which is a member of the object, that is pointed to by a. It is shorthand of (*a).b and so here, a is pr...
Add Keypair to existing EC2 instance
... lost your ssh key or forgot your password
You made a mistake editing the /etc/sudoers file and can no longer
gain root access with sudo to fix it
Your long running instance is hung for some reason, cannot be
contacted, and fails to boot properly
You need to recover files off of the instance but can...
Count, size, length…too many choices in Ruby?
...block_given_p())
return LONG2NUM(RARRAY_LEN(ary));
// etc..
}
}
The code for array.count does a few extra checks but in the end calls the exact same code: LONG2NUM(RARRAY_LEN(ary)).
Hashes (source code) on the other hand don't seem to implement their own optimized version...
Duplicate and rename Xcode project & associated folders [closed]
...s, but it's not the clearest file structure for people to navigate in SCM, etc. To rename this folder without breaking all your file links, follow these steps:
In the Finder, rename the source folder. This will break your project, because Xcode won't automatically detect the changes. All of your x...
Why would iterating over a List be faster than indexing through it?
...inter to the next element:
head -> item1 -> item2 -> item3 -> etc.
To access item3, you can see clearly that you need to walk from the head through every node until you reach item3, since you cannot jump directly.
Thus, if I wanted to print the value of each element, if I write this:...
Why is my Android emulator keyboard in Chinese character mode?
...
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Create code first, many to many, with additional fields in association table
...berComments { get; set; }
}
public class MemberComment
{
[Key, Column(Order = 0)]
public int MemberID { get; set; }
[Key, Column(Order = 1)]
public int CommentID { get; set; }
public virtual Member Member { get; set; }
public virtual Comment Comment { get; set; }
publi...
What exactly does the post method do?
...ssage queue.
So startAnimation will be fired in a new thread when it is fetched from the messageQueue
[EDIT 1]
Why do we use a new thread instead of UI thread (main thread)?
UI Thread :
When application is started, Ui Thread is created automatically
it is in charge of dispatching the events...