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postgresql - add boolean column to table set default
...D COLUMN priv_user BOOLEAN;, then UPDATE users SET priv_user = 'f'; and finally if you need to ALTER TABLE users ALTER COLUMN priv_user SET NOT NULL;.
– Craig Ringer
Aug 14 '12 at 0:19
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Fastest way to get the first object from a queryset in django?
...eturn None if there aren't any. There are lots of ways to do this which all work. But I'm wondering which is the most performant.
...
Start thread with member function
...t one of the types described in the previous item;
f(t1, t2, ..., tN) in all other cases.
Another general fact which I want to point out is that by default the thread constructor will copy all arguments passed to it. The reason for this is that the arguments may need to outlive the calling ...
Passing a function with parameters as a parameter?
...nction wrapper that knows about the parameter and passes it to the actual callback implementation.
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Sass .scss: Nesting and multiple classes?
... &:nth-child(1){ ... }
}
However, you can place the & at virtually any position you like*, so the following is possible too:
.container {
background:red;
#id &{
background:blue;
}
}
/* compiles to: */
.container {
background: red;
}
#id .container {
back...
How to correctly close a feature branch in Mercurial?
...heads anymore. The only thing that could possibly annoy you is that technically the revision graph will still have one more revision without childen.
Update 2: Since Mercurial 1.8 bookmarks have become a core feature of Mercurial. Bookmarks are more convenient for branching than named branches. See...
How to find a min/max with Ruby
...ray#max, which are way faster than Enumerable's methods because they skip calling #each.
@nicholasklick mentions another option, Enumerable#minmax, but this time returning an array of [min, max].
[4, 5, 7, 10].minmax
=> [4, 10]
...
EJB's - when to use Remote and/or local interfaces?
...be remote components and the only way to invoke them was to make a remote call, using RMI semantics and all the overhead it implies (a network call and object serialization for every method call). EJB clients had to pay this performance penalty even when collocated in the same virtual machine with t...
What is the difference between ~> and >= when specifying rubygem in Gemfile?
... and use that until it reaches a maximum version. So ~>0.8.5 is semantically equivalent to:
gem "cucumber", ">=0.8.5", "<0.9.0"
The easy way to think about it is that you're okay with the last digit incrementing to some arbitrary value, but the ones preceding it in the string cannot be gr...
When and why would you seal a class?
... features, so that the original object cannot be "impersonated".
More generally, I recently exchanged with a person at Microsoft, who told me they tried to limit the inheritance to the places where it really made full sense, because it becomes expensive performance-wise if left untreated. The sealed...