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What is a columnar database?
...se is a concept rather a particular architecture/implementation. In other words, there isn't one particular description on how these databases work; indeed, several are build upon traditional, row-oriented, DBMS, simply storing the info in tables with one (or rather often two) columns (and adding t...
What's the difference between RANK() and DENSE_RANK() functions in oracle?
... 8 | 8 | 5 |
+---+------------+------+------------+
In words
ROW_NUMBER() attributes a unique value to each row
RANK() attributes the same row number to the same value, leaving "holes"
DENSE_RANK() attributes the same row number to the same value, leaving no "holes"
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Random record in ActiveRecord
...can (or table scan, in case clustered index is used like InnoDB). In other words, it's O(N) operation but "WHERE id >= #{rand_id} ORDER BY id ASC LIMIT 1" is O(log N), which is much faster.
– kenn
May 6 '11 at 1:02
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Why do python lists have pop() but not push()
...rticular
semantics, write a little class that
uses a lists
In other words, for stacks implemented directly as Python lists, which already supports fast append(), and del list[-1], it makes sense that list.pop() work by default on the last element. Even if other languages do it differently.
I...
Is there a way to change the environment variables of another process in Unix?
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@kilaka: The key word is the second one — No. The rest of the answer is saying that if you have root privileges or are running a debugger, then maybe you can do it, but for all practical purposes, the answer is No.
– ...
I do not want to inherit the child opacity from the parent in CSS
...tually inherited in CSS. It's a post-rendering group transform. In other words, if a <div> has opacity set you render the div and all its kids into a temporary buffer, and then composite that whole buffer into the page with the given opacity setting.
What exactly you want to do here depends...
Functions that return a function
...ts, like any other object. If you find that not helpful, just replace the word "object" with "thing". You can return any object from a function. You can return a true/false value. An integer (1,2,3,4...). You can return a string. You can return a complex object with multiple properties. And y...
Recursion or Iteration?
...ursive function and the benefits of using tail-end recursion. His closing words really summed up some of my key points I think:
"recursive programming gives the programmer a better way of organizing
code in a way that is both maintainable and logically consistent."
https://developer.ibm...
Python append() vs. + operator on lists, why do these give different results?
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if an element is single string, e.g. s = 'word', l = ['this', 'is']. Then l.append(s) and l+s should be the same. Am I correct?
– user3512680
Feb 2 at 22:13
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Update R using RStudio
...swer that you must close and reopen RStudio (or restart RStudio, whichever wording you prefer). The "Then you change the path in your Rstudio option :Tools -> options -> General" did not work for me. However, restarting R did, so it would be good to update your answer to include this info.
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