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postgresql COUNT(DISTINCT …) very slow
...ount int not null), using triggers. But your write performance will suffer and if you update multiple x values in single transaction then you'd need to do this in some explicit order to avoid possible deadlock.
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Why is there no logical xor in JavaScript?
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JavaScript traces its ancestry back to C, and C does not have a logical XOR operator. Mainly because it's not useful. Bitwise XOR is extremely useful, but in all my years of programming I have never needed a logical XOR.
If you have two boolean variables you can mim...
RVM is not a function, selecting rubies with 'rvm use …' will not work
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Your console is not running as a login shell and hence have no access to rvm function. If you are running Ubuntu, you can:
Open console
Select Edit -> Profile Preferences
Select tab: Title and Command
Check box 'Run command as a login shell'
Restart terminal
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Get commit list between tags in git
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To compare between latest commit of current branch and a tag:
git log --pretty=oneline HEAD...tag
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PostgreSQL array_agg order
...rray_agg would then be unordered but it would be the same in both columns. And if you like you could add an ORDER BY clause to the subquery.
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Why does Bootstrap set the line-height property to 1.428571429?
...re you have ample white space between your rows. This allows for ascenders and descenders without intruding on other rows. Also having ample white space allows your eyes to develop a visual rhythm while reading.
Also keeping the line-height unitless makes it more versatile. For more information, se...
How do I clone a GitHub wiki?
...thub.com:myusername/foobar.git would be the path to clone your repository
and
git clone git@github.com:myusername/foobar.wiki.git would be the path to clone its wiki.
Note: You must have at least one page to be able to clone the wiki repo. (via @tobiasz-cudnik)
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How to delete a row by reference in data.table?
...estion. data.table can't delete rows by reference yet.
data.table can add and delete columns by reference since it over-allocates the vector of column pointers, as you know. The plan is to do something similar for rows and allow fast insert and delete. A row delete would use memmove in C to budge u...
Create an empty data.frame
...hout any rows. Basically, I want to specify the data types for each column and name them, but not have any rows created as a result.
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How to create a date object from string in javascript [duplicate]
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Surprised someone noticed this about 1.5 years and 24,000+ views later.
– Dogbert
Oct 2 '13 at 6:18
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