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Postgres: INSERT if does not exist already
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Postgres 9.5 (released since 2016-01-07) offers an "upsert" command, also known as an ON CONFLICT clause to INSERT:
INSERT ... ON CONFLICT DO NOTHING/UPDATE
It solves many of the subtle problems you can run into when using concurrent operation, which some other answers propose.
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Does ARC support dispatch queues?
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The short answer: YES, ARC retains and releases dispatch queues.
And now for the long answer…
If your deployment target is lower than iOS 6.0 or Mac OS X 10.8
You need to use dispatch_retain and dispatch_release on your queue. ARC does not manage ...
How does the getView() method work when creating your own custom adapter?
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1: The LayoutInflater takes your layout XML-files and creates different View-objects from its contents.
2: The adapters are built to reuse Views, when a View is scrolled so that is no longer visible, it can be used for one of the new Views appearing. This reused View is t...
Order Bars in ggplot2 bar graph
...g to make a bar graph where the largest bar would be nearest to the y axis and the shortest bar would be furthest. So this is kind of like the Table I have
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Why does (i
... j is evaluated to true, because auto unboxing happens for int
comparisons and then both i and j hold the default value, 0.
j <= i is evaluated to true because of the above reason.
i != j is evaluated to true, because both i and j are
different objects. And while comparing objects, there isn't an...
sed in-place flag that works both on Mac (BSD) and Linux
...on of sed todo in-place editing without backups that works both on Linux and Mac? While the BSD sed shipped with OS X seems to need sed -i '' … , the GNU sed Linux distributions usually come with interprets the quotes as empty input file name (instead of the backup extension), and needs se...
How to import existing Git repository into another?
I have a Git repository in a folder called XXX , and I have second Git repository called YYY .
15 Answers
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Can I run javascript before the whole page is loaded?
...er encounters a classic script tag when parsing the HTML, it stops parsing and hands over to the JavaScript interpreter, which runs the script. The parser doesn't continue until the script execution is complete (because the script might do document.write calls to output markup that the parser should...
Difference between Pig and Hive? Why have both? [closed]
...y background - 4 weeks old in the Hadoop world. Dabbled a bit in Hive, Pig and Hadoop using Cloudera's Hadoop VM. Have read Google's paper on Map-Reduce and GFS ( PDF link ).
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Installing SetupTools on 64-bit Windows
I'm running Python 2.7 on Windows 7 64-bit, and when I run the installer for setuptools it tells me that Python 2.7 is not installed. The specific error message is:
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