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What is the “N+1 selects problem” in ORM (Object-Relational Mapping)?
...bject-Relational mapping (ORM) discussions, and I understand that it has something to do with having to make a lot of database queries for something that seems simple in the object world.
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Is recursion ever faster than looping?
I know that recursion is sometimes a lot cleaner than looping, and I'm not asking anything about when I should use recursion over iteration, I know there are lots of questions about that already.
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Difference between Big-O and Little-O Notation
...you find a particular multiplier k for which the inequality holds beyond some minimum x.
In Little-o, it must be that there is a minimum x after which the inequality holds no matter how small you make k, as long as it is not negative or zero.
These both describe upper bounds, although somewhat co...
MongoDB Many-to-Many Association
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Depending on your query needs you can put everything in the user document:
{name:"Joe"
,roles:["Admin","User","Engineer"]
}
To get all the Engineers, use:
db.things.find( { roles : "Engineer" } );
If you want to maintain the roles in separate documents then you can include the document's...
Git commits are duplicated in the same branch after doing a rebase
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You should not be using rebase here, a simple merge will suffice. The Pro Git book that you linked basically explains this exact situation. The inner workings might be slightly different, but here's how I visualize it:
C5 and C6 are temporarily pulled out of dev
C7 is ...
Why is require_once so bad to use?
...em keeps a log of what's already been included/required. Every *_once call means checking that log. So there's definitely some extra work being done there but enough to detriment the speed of the whole app?
... I really doubt it... Not unless you're on really old hardware or doing it a lot.
If yo...
Why are elementwise additions much faster in separate loops than in a combined loop?
Suppose a1 , b1 , c1 , and d1 point to heap memory and my numerical code has the following core loop.
10 Answers
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Abusing the algebra of algebraic data types - why does this work?
...'algebraic' expression for algebraic data types looks very suggestive to someone with a background in mathematics. Let me try to explain what I mean.
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Byte order mark screws up file reading in Java
I'm trying to read CSV files using Java. Some of the files may have a byte order mark in the beginning, but not all. When present, the byte order gets read along with the rest of the first line, thus causing problems with string compares.
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Can someone explain __all__ in Python?
...seeing the variable __all__ set in different __init__.py files. Can someone explain what this does?
11 Answers
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