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What is the “N+1 selects problem” in ORM (Object-Relational Mapping)?
... Wheel
This reduces the number of round-trips to the database from N+1 to 2.
Most ORM tools give you several ways to prevent N+1 selects.
Reference: Java Persistence with Hibernate, chapter 13.
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Convert light frequency to RGB?
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answered Sep 24 '09 at 15:47
Stephen MesaStephen Mesa
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Numpy argsort - what is it doing?
... to the documentation
Returns the indices that would sort an array.
2 is the index of 0.0.
3 is the index of 0.1.
1 is the index of 1.41.
0 is the index of 1.48.
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Disable a group of tests in rspec?
... in the output:
before { skip("Awaiting a fix in the gem") }
with RSpec 2:
before { pending }
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Join a list of items with different types as string in Python
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answered Aug 28 '10 at 9:09
Mark ByersMark Byers
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How do I immediately execute an anonymous function in PHP?
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121
For PHP7: see Yasuo Ohgaki's answer: (function() {echo 'Hi';})();
For previous versions: the o...
Can you have if-then-else logic in SQL? [duplicate]
...e1 WHERE project = 1
ELSE IF ((SELECT COUNT(*) FROM table1 WHERE project = 2) > 0)
SELECT product, price FROM table1 WHERE project = 2
ELSE IF ((SELECT COUNT(*) FROM table1 WHERE project = 3) > 0)
SELECT product, price FROM table1 WHERE project = 3
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How do I get the row count of a pandas DataFrame?
...setup=lambda n: pd.DataFrame(np.arange(n * 3).reshape(n, 3)),
n_range=[2**k for k in range(25)],
kernels=[
lambda data: data.shape[0],
lambda data: data[0].count(),
lambda data: len(data.index),
],
labels=["data.shape[0]", "data[0].count()", "len(data.index)"]...
What is the difference between “text” and new String(“text”)?
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