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What is the “N+1 selects problem” in ORM (Object-Relational Mapping)?
...f Home with ID=1, Address="22 Valley St" and then populate the Inhabitants array with People instances for Dave, John, and Mike with just one query.
A N+1 query for the same address used above would result in:
Id Address
1 22 Valley St
with a separate query like
SELECT * FROM Person WHERE Hous...
When to use the brace-enclosed initializer?
...a list of values to be stored in the object (like the elements of a vector/array, or real/imaginary part of a complex number), use curly braces initialization if available.
If the values you are initializing with are not values to be stored, but describe the intended value/state of the object, use p...
Is recursion ever faster than looping?
...e final and intermediate result values. Let’s assume we have an infinite array of "integer" cells, called Memory, M[0..Infinite].
Instructions: do something - transform a cell, change its value. alter state. Every interesting instruction performs a transformation. Basic instructions are:
a) Set ...
javascript: recursive anonymous function?
...eed to keep track of additional state?
We could use compound data like an Array or something...
const U = f => f (f)
const Y = U (h => f => f (x => U (h) (f) (x)))
const fibonacci = Y (f => ([a, b, x]) =>
x === 0 ? a : f ([b, a + b, x - 1]))
// starting with 0 and...
How do I adjust the anchor point of a CALayer, when Auto Layout is being used?
...g it purely by its center. After that, my scale transform works:
NSMutableArray* cons = [NSMutableArray array];
for (NSLayoutConstraint* con in self.view.constraints)
if (con.firstItem == self.otherView || con.secondItem == self.otherView)
[cons addObject:con];
[self.view removeConstra...
What would cause an algorithm to have O(log log n) complexity?
...tion search has expected runtime O(log log n) to find a number in a sorted array, but the analysis is fairly involved. Ultimately, the analysis works by showing that the number of iterations is equal to the number k such that n2-k ≤ 2, for which log log n is the correct solution. Some algorithms,...
How to read contacts on Android 2.0
...es
// if the email addresses were stored in an array
String email = emailCur.getString(
emailCur.getColumnIndex(ContactsContract.CommonDataKinds.Email.DATA));
String emailType = emailCur...
Which iomanip manipulators are 'sticky'?
...ostream instantiation or char, signed char or unsigned char or pointers to arrays of these char types.
To be honest I'm not sure of the rationale for this, but no other states of an ostream should be reset by formatted output functions. Of course, things like badbit and failbit may be set if there ...
What do Clustered and Non clustered index actually mean?
...f level by following the linked list and read the rows on the page in slot array order then you will read the index rows in sorted order but physically the pages may not be sorted. The commonly held belief that with a clustered index the rows are always stored physically on the disk in the same orde...
What are the most widely used C++ vector/matrix math/linear algebra libraries, and their cost and be
... in another lib is only available via myVec[0] (Readability problem)
an array or stl::vector of points may cause you to do something like pointsList[0][0] to access the x component of the first point
in a naive attempt at optimization, removed cross(vec,vec) and
replaced with makeCross(vec,vec,...