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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?
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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...
How to disallow temporaries
For a class Foo, is there a way to disallow constructing it without giving it a name?
10 Answers
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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?
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> 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...
Remove menu and status bars in TinyMCE 4
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Small typo: menuBar: 'file edit' should be menubar: 'file edit'
– Cory Mawhorter
May 27 '13 at 9:49
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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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RSpec controller testing - blank response.body
...with a problem when testing my controllers with RSpec - the response.body call always returns an empty string. In browser everything renders correctly, and cucumber feature tests seem to get it right, but RSpec fails each and every time.
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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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