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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...
What's the difference between utf8_general_ci and utf8_unicode_ci?
Between utf8_general_ci and utf8_unicode_ci , are there any differences in terms of performance?
8 Answers
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read.csv warning 'EOF within quoted string' prevents complete reading of file
...112,544 rows. When I read it into R with read.csv I only get 56,952 rows and this warning:
8 Answers
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Efficient Algorithm for Bit Reversal (from MSB->LSB to LSB->MSB) in C
... trade off memory for speed (assuming your L1 Data Cache is large enough), and reverse 16 bits at a time with a 64K-entry lookup table.
Others
Simple
unsigned int v; // input bits to be reversed
unsigned int r = v & 1; // r will be reversed bits of v; first get LSB of v
int s = sizeof(v...
Why is argc not a constant?
...this case, history is a factor. C defined these inputs as "not constant", and compatibility with (a good portion of) existing C code was an early goal of C++.
Some UNIX APIs, such as getopt, actually do manipulate argv[], so it can't be made const for that reason also.
(Aside: Interestingly, al...
Ruby optional parameters
...his method: e.g. If you're trying to make the default value for scope true and you pass in false, scope ||= true won't work. It evaluates the same as nil and will set it to true
– Joshua Pinter
Nov 10 '11 at 5:32
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How to exit in Node.js
What is the command that is used to exit? (i.e terminate the Node.js process)
19 Answers
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This app won't run unless you update Google Play Services (via Bazaar)
I'm testing out the new Google Maps API V2 for Android, and I'm getting this message when the app launches:
12 Answers
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How to get the part of a file after the first line that matches a regular expression?
...g the TERMINATE regular expression (like grep) to the end of the file ($), and p is the print command which prints the current line.
This will print from the line that follows the line matching TERMINATE till the end of the file:
(from AFTER the matching line to EOF, NOT including the matching line...
Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_
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Culprit: False Data Dependency (and the compiler isn't even aware of it)
On Sandy/Ivy Bridge and Haswell processors, the instruction:
popcnt src, dest
appears to have a false dependency on the destination register dest. Even though the instruction only...