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How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
... preferred whenever practical.
In this case, you typically follow the following process:
CREATE a TEMPORARY table
COPY or bulk-insert the new data into the temp table
LOCK the target table IN EXCLUSIVE MODE. This permits other transactions to SELECT, but not make any changes to the table.
Do an ...
How can I pair socks from a pile efficiently?
...ent than a modern CPU, this question makes no practical sense.
Humans can win over CPU algorithms using the fact that "finding a matching pair" can be one operation for a set that isn't too big.
My algorithm:
spread_all_socks_on_flat_surface();
while (socks_left_on_a_surface()) {
// Thanks t...
Is 'switch' faster than 'if'?
...s that holds pointer to the labels in something like array structure. following example will help you understand how jump tables are laid out
00B14538 D8 09 AB 00 D8 09 AB 00 D8 09 AB 00 D8 09 AB 00 Ø.«.Ø.«.Ø.«.Ø.«.
00B14548 D8 09 AB 00 D8 09 AB 00 D8 09 AB 00 00 00 00 00 Ø.«.Ø.«.Ø...
What’s the difference between ScalaTest and Scala Specs unit test frameworks?
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The readability of scalatest is a major winning point over scala specs for me.
– nemoo
Jan 20 '14 at 9:07
add a comment
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What does SynchronizationContext do?
...es end up running is dependent on the type of SynchronizationContext used.
Windows Forms will install a WindowsFormsSynchronizationContext on the thread on which the first form is created. (This thread is commonly called "the UI thread".) This type of synchronization context invokes the delegates pa...
Determining complexity for recursive functions (Big O notation)
...4, even though the result is the same, shouldn't the induction be the following? T(n) = a + 2T(n-1) = a + 2a + 4T(n-1) = 3a + 4a + 8T(n-1) = a * (2^n - 1) + 2^n * T(0) = a * (2^n - 1) + b * 2^n = (a + b) * 2^n - a = O(2^n)
– Snowfish
Jan 3 at 22:59
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Why doesn't C++ have a garbage collector?
...the paper made a good job of introducing the concepts one at a time and showing the evolution of the algorithm from the "simple" version to the full-fledged one. Recommended reading if only I could put my hands back on the PDF file...
2. Resources Acquisition Is Initialization (RAII)
It's a common...
Git Symlinks in Windows
Our developers use a mix of Windows and Unix based OS's. Therefore, symlinks created on Unix machines become a problem for Windows developers. In windows (msysgit), the symlink is converted to a text file with a path to the file it points to. Instead, I'd like to convert the symlink into an actual W...
C++ performance challenge: integer to std::string conversion
...--- 10.230 s
ergosys: 101.42 MB/sec --- 9.860 s
MSVC 2010 64-bit /Ox on Windows 7 64-bit, Core i5
hopman_fun: 127 MB/sec --- 7.874 s
hopman_fast: 259 MB/sec --- 3.861 s
voigt: 221.435 MB/sec --- 4.516 s
user_voigt_timo: 195.695 MB/sec --- 5.110 s
timo: 253.165 MB/sec --- 3.950 s
user: 212....
What's the fastest way to merge/join data.frames in R?
... issue? For example I'm guessing that SEM=Scanning electron microscope? Knowing more about the application makes it more interesting to us and helps us prioritise.
– Matt Dowle
Aug 12 '14 at 12:00
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