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What's faster, SELECT DISTINCT or GROUP BY in MySQL?
...he output, and GROUP BY by default does. However, in MySQL even a DISTINCT+ORDER BY might still be faster than a GROUP BY due to the extra hints for the optimizer as explained by SquareCog.
– rustyx
Jan 25 '15 at 15:03
...
Webfonts or Locally loaded fonts?
...e file size logic is also, I believe, why Font Squirrel tries them in that order. But that is mostly speculation on my part.
If you're working in an environment where every request and byte counts, you'll have to do some profiling to find out which works best for your use case. Will people be only ...
Efficiently convert rows to columns in sql server
... yourtable
group by ColumnName, id
order by id
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set @query = N'SELECT ' + @cols + N' from
(
select value, ColumnName
fr...
Android EditText delete(backspace) key event
...ction class. This method is called when key events occur in an IME. But in order to override this, we need to implement a custom EditText which overrides the onCreateInputConnection method, wrapping the default InputConnection object in a proxy class! :|
Sounds complicated, but here's the simplest ...
Big-oh vs big-theta [duplicate]
...case in very common circumstances - the classic example being inserting in-order into a binary tree to get what's effectively a singly-linked list. A "real" assessment of average performance needs to take into account the relative frequency of different kinds of input.
...
How to run a shell script at startup
...
In the file you put in /etc/init.d/ you have to set it executable with:
chmod +x /etc/init.d/start_my_app
Thanks to @meetamit, if this does not run you have to create a symlink to /etc/rc.d/
ln -s /etc/init.d/start_my_app /etc/rc.d/
Please not...
Write text files without Byte Order Mark (BOM)?
...to do this?
I can write file with UTF8 encoding but, how to remove Byte Order Mark from it?
9 Answers
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Input and output numpy arrays to h5py
...pe float . If I save it with the extension .dat the file size is of the order of 500 MB. I read that using h5py reduces the file size considerably. So, let's say I have the 2D numpy array named A . How do I save it to an h5py file?
Also, how do I read the same file and put it as a numpy array ...
What is a “cache-friendly” code?
... algorithm design
Whenever possible, try to adapt your data structures and order of computations in a way that allows maximum use of the cache. A common technique in this regard is cache blocking (Archive.org version), which is of extreme importance in high-performance computing (cfr. for example AT...
What is Bit Masking?
...ing a mask to a value. This is accomplished by doing:
Bitwise ANDing in order to extract a subset of the bits in the value
Bitwise ORing in order to set a subset of the bits in the value
Bitwise XORing in order to toggle a subset of the bits in the value
Below is an example of extracting a subs...