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Simple explanation of MapReduce?
...e reduced to a scalar value.
So if you think of it like a SQL statement
SELECT SUM(salary)
FROM employees
WHERE salary > 1000
GROUP by deptname
We can use map to get our subset of employees with salary > 1000
which map emits to the barrier into group size buckets.
Reduce will sum each of...
Homebrew install specific version of formula?
...installed. If you are missing the version you will still need to apply the selected answer.
– Nic Strong
Dec 19 '13 at 5:11
1
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What are the main performance differences between varchar and nvarchar SQL Server data types?
... AND ([URLa] IS NULL OR [URLu] IS NULL))
);
In this model you only SELECT from the [URL] computed column. For inserting and updating, you determine which field to use by seeing if converting alters the incoming value, which has to be of NVARCHAR type:
INSERT INTO TableName (..., URLa, URLu)...
What is the difference between Serializable and Externalizable in Java?
...
We used Externalizable for large collections of "selected IDs" -- it was far more efficient externalizing as more-or-less a count & an array of primitive ints, than default serialization. That's a very simple usecase, nothing "special" or "unique".
...
What is the performance cost of having a virtual method in a C++ class?
..."type(-identifying) number" in the objects and using a switch statement to select the type-specific code. This avoids function call overhead completely - just doing a local jump. There is a potential cost to maintainability, recompilation dependencies etc through the forced localisation (in the sw...
No ConcurrentList in .Net 4.0?
...or all items 0-63, and a size-128 array for items 64-127. The overhead of selecting which one of two arrays to use, plus a memory barrier if desired, would be less than the overhead of even the most efficient reader-writer lock imaginable. Writes should probably use locks (lock-free would be possi...
How exactly does the “Specific Version” property of an assembly reference work in Visual Studio?
...u examine the properties of an assembly reference in the Visual Studio UI (select the reference and hit F4), the value you see for the "Specific Version" property tells you whether or not Visual Studio is going to perform the "Specific Version" check. In case 6 the UI will show "True", although the ...
Why not inherit from List?
...is the collective name given to a group of players ... Such teams could be selected to play in a match against an opposing team, to represent a football club ...". So it is my opinion that a team is a list of players (or perhaps more accurately a collection of players).
– Ben
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Finding a branch point with Git?
...ed from master):
or here (as viewed from topic):
in both cases, I've selected the commit that is B in my graph. Once you click on it, its full SHA is presented in a text input field just below the graph.
2. visually, but from the terminal:
git log --graph --oneline --all
(Edit/side-note:...
Switch statement fallthrough in C#?
...# had not yet added any "soft" keywords (like 'yield', 'var', 'from', and 'select'), so they had three real options: 1) make 'fallthrough' a hard keyword (you cant use it as a variable name), 2) write code necessary to support such an soft keyword, 3) use already reserved keywords. #1 was a big issu...