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Two single-column indexes vs one two-column index in MySQL?
...
"MySQL can use multiple-column indexes for queries that test all the columns in the index, or queries that test just the first column, the first two columns, the first three columns, and so on. If you specify the columns in the right order in the index definition, a single composi...
In-Place Radix Sort
...should be fast.
Edit:
I got curious whether this code actually works, so I tested/debugged it while waiting for my own bioinformatics code to run. The version above now is actually tested and works. For 10 million sequences of 5 bases each, it's about 3x faster than an optimized introsort.
...
How can you find the height of text on an HTML canvas?
...t, descent and height (which is just ascent + descent for convenience). To test it, it's worth having a function that draws a horizontal line:
var testLine = function(ctx, x, y, len, style) {
ctx.strokeStyle = style;
ctx.beginPath();
ctx.moveTo(x, y);
ctx.lineTo(x + len, y);
ctx.closePat...
Java 8 Streams - collect vs reduce
...Salary);
}
public Integer getSalary(){
return this.salary;
}
}
@Test
public void testReduceWithImmutable(){
List<Employee> list = new LinkedList<>();
list.add(new Employee("1"));
list.add(new Employee("2"));
list.add(new Employee("3"));
Integer sum = list
.stream(...
Is this a “good enough” random algorithm; why isn't it used if it's faster?
...ckage com.stackoverflow.q14491966;
import java.util.Arrays;
public class Test {
public static void main(String[] args) throws Exception {
QuickRandom qr = new QuickRandom();
int[] frequencies = new int[10];
for (int i = 0; i < 100000; i++) {
frequencies[...
How to pass command line arguments to a rake task
...onParser) you could use something like this:
$ rake user:create -- --user test@example.com --pass 123
note the --, that's necessary for bypassing standard Rake arguments. Should work with Rake 0.9.x, <= 10.3.x.
Newer Rake has changed its parsing of --, and now you have to make sure it's not p...
DynamoDB vs MongoDB NoSQL [closed]
... but after transferred to DynamoDB, occupy only 300M storage. I may need a test and see what the storage if I migrate those data to MongoLab :)
– Mason Zhang
Aug 8 '13 at 7:51
1
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Why does Environment.Exit() not terminate the program any more?
...-duck out. It implements the Visual Styles theming API and is used by this test program. I can't be sure, but my money is on that one as the source of the problem. The copy in C:\WINDOWS\system32 has version number 6.2.9200.16660, created on August 14th, 2013 on my machine.
Case closed.
...
Finding what branch a Git commit came from
... command works like a charm:
git name-rev <SHA>
For example (where test-branch is the branch name):
git name-rev 651ad3a
251ad3a remotes/origin/test-branch
Even this is working for complex scenarios, like:
origin/branchA/
/branchB
/commit<SHA1>
...
node and Error: EMFILE, too many open files
...n...
To get a count of open files for a certain pid
I used this command to test the number of files that were opened after doing various events in my app.
lsof -i -n -P | grep "8465" | wc -l
# lsof -i -n -P | grep "nodejs.*8465" | wc -l
28
# lsof -i -n -P | grep "nodejs.*8465" | wc -l
31
# lsof -i ...