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Why does direction of index matter in MongoDB?
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MongoDB concatenates the compound key in some way and uses it as the key in a BTree.
When finding single items - The order of the nodes in the tree is irrelevant.
If you are returning a range of nodes - The elements close to each other will be down the same branches of th...
Laravel Check If Related Model Exists
...$relation) is a general solution for all relations. It will work for Model and Collection, while Model has no ->count() method.
– Jarek Tkaczyk
Jul 29 '14 at 17:16
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Bytecode features not available in the Java language
...s, however:
The ACC_SUPER flag:
This is a flag that can be set on a class and specifies how a specific corner case of the invokespecial bytecode is handled for this class. It is set by all modern Java compilers (where "modern" is >= Java 1.1, if I remember correctly) and only ancient Java compil...
What does `kill -0 $pid` in a shell script do?
... 0 to a given PID just checks if any process with the given PID is running and you have the permission to send a signal to it.
For more information see the following manpages:
kill(1)
$ man 1 kill
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If sig is 0, then no signal is sent, but error checking is still performed.
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kill(2)
$ man...
How do you attach and detach from Docker's process?
...nal info from this source:
docker run -t -i → can be detached with ^P^Qand reattached with docker attach
docker run -i → cannot be detached with ^P^Q; will disrupt stdin
docker run → cannot be detached with ^P^Q; can SIGKILL client; can reattach with docker attach
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What's the difference between using CGFloat and float?
...mething "heavier" than float, right? At which points should I use CGFloat, and what makes really the difference?
5 Answers
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What's the difference between design patterns and architectural patterns?
...ou find in programs. It allows us to deconstruct a large complex structure and build using simple parts. It provides a general solution for a class of problems.
A large complex software goes through a series of deconstruction at different levels. At large level, architectural patterns are the tool...
How do I convert a float number to a whole number in JavaScript?
...e number in JavaScript. Actually, I'd like to know how to do BOTH of the standard conversions: by truncating and by rounding. And efficiently, not via converting to a string and parsing.
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MIN/MAX vs ORDER BY and LIMIT
...d field, using MIN() requires a single full pass of the table. Using SORT and LIMIT requires a filesort. If run against a large table, there would likely be a significant difference in percieved performance. As a meaningless data point, MIN() took .36s while SORT and LIMIT took .84s against a 106...
How do I concatenate or merge arrays in Swift?
... Khunshan: AnyObject indicates an object, which as I understand means something that is instantiated from a class type. CGFloat is not an object, it is a scalar value. As I understand it, arrays can contain scalars, unless it is defined as containing AnyObject or are further refined. ...