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What is a “Bitmap heap scan” in a query plan?
... stay in memory, but you get the point).
A bitmap index scan will sequentially open a short-list of disk pages, and grab every applicable row in each one (hence the so-called recheck cond you see in query plans).
Note, as an aside, how clustering/row order affects the associated costs with either ...
Checking if a key exists in a JavaScript object?
... testing whether a key exists. What if the key exists but the value is actually undefined?
var obj = { key: undefined };
obj["key"] !== undefined // false, but the key exists!
You should instead use the in operator:
"key" in obj // true, regardless of the actual value
If you want to check if a...
What is the use of hashCode in Java?
...
Buckets aside, hashcode is a method that the object calls to determine the order to store each object in memory. If objects are equal, then their hashcode must also be equal. (converse of this statement is false)
– NoName
Jun 24 '17 at 6:1...
Looping over a list in Python
I have a list with sublists in it. I want to print all the sublists with length equal to 3.
4 Answers
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How to “re-run with -deprecation for details” in sbt?
...
> compile
> exit
Due to in ThisBuild, set applies the settings to all sub-projects, as well.
Command Line
You could also run the above as a single command on command line.
sbt '; set scalacOptions in ThisBuild ++= Seq("-unchecked", "-deprecation") ; compile'
The trick is to use ; (sem...
ipython notebook clear cell output in code
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Using the clear_output(wait=True) will generally make the result nicer if you have clear_output inside a loop.
– Toke Faurby
Jun 8 '17 at 23:49
1
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Test if executable exists in Python?
... search for set in %PATHEXT%. That's not great, but it might work for the all the cases someone needs.
– rakslice
Oct 3 '13 at 0:42
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Defining static const integer members in class definition
My understanding is that C++ allows static const members to be defined inside a class so long as it's an integer type.
7 An...
Why are C++ inline functions in the header?
...ne the function.
Whether you should declare a function inline or not is usually a choice that you should make based on which version of the one definition rules it makes most sense for you to follow; adding inline and then being restricted by the subsequent constraints makes little sense.
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Sell me on const correctness
...ll, using const is good practice because...
It protects you from accidentally changing variables that aren't intended be changed,
It protects you from making accidental variable assignments, and
The compiler can optimize it. For instance, you are protected from
if( x = y ) // whoops, meant if(...