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Mongodb Explain for Aggregation framework
...ther manipulation will be in-memory (possibly using temporary files if the allowDiskUse option is set).
Optimizing pipelines
In general, you can optimize aggregation pipelines by:
Starting a pipeline with a $match stage to restrict processing to relevant documents.
Ensuring the initial $match / ...
Setting a system environment variable from a Windows batch file?
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The XP Support Tools (which can be installed from your XP CD) come with a program called setx.exe:
C:\Program Files\Support Tools>setx /?
SETX: This program is used to set values in the environment
of the machine or currently logged on user using one of three...
Parsing JSON Object in Java [duplicate]
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Performance of org.json is amongst the worst of all libraries + that lib was developed as proof of concept in the early days of JSON. Choose a json lib that performs well: github.com/fabienrenaud/java-json-benchmark
– fabien
Jun 27 '1...
Checking if a string is empty or null in Java [duplicate]
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@HonzaKalfus "Calling isEmpty() returns true for string containing whitespace character" - That is not true! " ".isEmpty() returns false
– MestreLion
Sep 1 '17 at 1:59
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Selectors in Objective-C?
First, I'm not sure I really understand what a selector is. From my understanding, it's the name of a method, and you can assign it to a class of type 'SEL' and then run methods such as respondToSelector to see if the receiver implements that method. Can someone offer up a better explanation?
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Is it safe to parse a /proc/ file?
.../proc/mounts was a consistent snapshot.
For example:
/proc/uptime is totally atomic, as someone mentioned in another answer -- but only since Linux 2.6.30, which is less than two years old. So even this tiny, trivial file was subject to a race condition until then, and still is in most enterpris...
What can be the reasons of connection refused errors?
...estination machine, but its backlog of pending connections is full.
A firewall between the client and server is blocking access (also check local firewalls).
After checking for firewalls and that the port is open, use telnet to connect to the ip/port to test connectivity. This removes any potentia...
Why have header files and .cpp files? [closed]
...dencies so that code that uses the header doesn't necessarily need to know all the details of the implementation and any other classes/headers needed only for that. This will reduce compilation times and also the amount of recompilation needed when something in the implementation changes.
It's not ...
How do you disable viewport zooming on Mobile Safari?
I've tried all three of these to no avail:
15 Answers
15
...
Assignment in an if statement
... = value as T;
if (t != null)
{
action(t);
}
}
Then call it with:
animal.AsIf<Dog>(dog => {
// Use dog in here
});
Alternatively, you could combine the two:
public static void AsIf<T>(this object value, Action<T> action) where T : class
{
// EVI...