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Why are joins bad when considering scalability?
...don't need to in volume, and the things you actually do you make sure are done as efficiently as possible.
In that context, of course joining two separate data sources is relatively slow, at least compared to not joining them, because it's work you need to do live at the point where the user request...
Difference between a “coroutine” and a “thread”?
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Coroutines are a form of sequential processing: only one is executing at any given time (just like subroutines AKA procedures AKA functions -- they just pass the baton among each other more fluidly).
Threads are (at least conceptually) a form of concurrent processing: multip...
Passing functions with arguments to another function in Python?
... What about named parameters? That is, def action1(arg1, arg2=None, arg3=None), how could you pass an argument that you intend to be assigned to arg3, for instance?
– ChaimKut
Aug 19 '14 at 9:54
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Query for documents where array size is greater than 1
...javascript in the query, json can be cumbersome. Many of these queries are one time only entered by hand so optimization is not required. I'll use this trick often +1
– pferrel
Mar 20 '14 at 15:37
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Double Iteration in List Comprehension
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I hope this helps someone else since a,b,x,y don't have much meaning to me! Suppose you have a text full of sentences and you want an array of words.
# Without list comprehension
list_of_words = []
for sentence in text:
for word in sentence:
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Good examples of Not a Functor/Functor/Applicative/Monad?
While explaining to someone what a type class X is I struggle to find good examples of data structures which are exactly X.
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How do I (or can I) SELECT DISTINCT on multiple columns?
...ND s1.ctid <> s.ctid
Every table should have a primary key. Add one if you didn't have one, yet. I suggest a serial or an IDENTITY column in Postgres 10+.
Related:
In-order sequence generation
Auto increment table column
How is this faster?
The subquery in the EXISTS anti-semi-join ...
Using global variables between files?
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wow, normally one would expect two files importing each other to get into an infinite loop.
– Nikhil VJ
Aug 24 '18 at 4:11
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What is the difference between `new Object()` and object literal notation?
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They both do the same thing (unless someone's done something unusual), other than that your second one creates an object and adds a property to it. But literal notation takes less space in the source code. It's clearly recognizable as to what is happening, so usin...
python numpy ValueError: operands could not be broadcast together with shapes
...hape (97,2)
y, shape (2,1)
With Numpy arrays, the operation
X * y
is done element-wise, but one or both of the values can be expanded in one or more dimensions to make them compatible. This operation are called broadcasting. Dimensions where size is 1 or which are missing can be used in broadca...