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How to speed up insertion performance in PostgreSQL
...rypto module) is (a lot) faster than uuid_generate_v4()
=# explain analyze select uuid_generate_v4(),* from generate_series(1,10000);
QUERY PLAN
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Get path of executable
... the predefined OS macros detailed at predef.sourceforge.net/preos.html to select the method is straightforward.
– Clifford
Oct 7 '09 at 15:02
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Convert data.frame columns from factors to characters
... can create a logical vector of which columns are factors, and use that to selectively apply factor
f <- sapply(bobf, class) == "factor"
bobc[,f] <- lapply(bobc[,f], factor)
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How does one generate a random number in Apple's Swift language?
...nteger between 0 and n-1.
let diceRoll = Int(arc4random_uniform(6) + 1)
Cast the result to Int so you don't have to explicitly type your vars as UInt32 (which seems un-Swifty).
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Convert a string to an enum in C#
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Come on, how many of you implemented that selected answer from 2008 to only scroll down and find this is the better (modern) answer.
– TEK
Mar 18 '16 at 14:47
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How to avoid overflow in expr. A * B - C * D
...ere's a work-around that only relies on implementation-defined behavior of casting unsigned integer to signed integer. But this can be expected to work on almost every system today.
(long long)((unsigned long long)A * B - (unsigned long long)C * D)
This casts the inputs to unsigned long long wher...
How can I convert NSDictionary to NSData and vice versa?
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For NSData -> NSDictionary, the cast to NSDictionary seems unnecessary.
– Pang
Dec 30 '15 at 8:11
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Swapping two variable value without using third variable
...ks for all integer values (that includes pointers then, with some luck and casting). For the sake of completeness I would like to mention another less powerful algorithm with addition/subtraction:
A = A + B
B = A - B
A = A - B
Here you have to be careful of overflows/underflows, but otherwise it ...
How to store arrays in MySQL?
... retrieve a person and all of their fruit you can do something like this:
SELECT p.*, f.*
FROM person p
INNER JOIN person_fruit pf
ON pf.person_id = p.id
INNER JOIN fruits f
ON f.fruit_name = pf.fruit_name
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java.util.Date to XMLGregorianCalendar
...est voted answer by Ben Noland uses the JVMs current default time zone for selecting the offset of the XMLGregorianCalendar. To include an offset in a modern object we use an OffsetDateTime. For example:
ZoneId zone = ZoneId.of("America/Asuncion");
OffsetDateTime dateTime = yourInstant.atZo...