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Database Structure for Tree Data Structure
...n choosing a model are:
1) Frequency of structure change - how frequently does the actual structure of the tree change. Some models provide better structure update characteristics. It is important to separate structure changes from other data changes however. For example, you may want to model a co...
Postgresql - change the size of a varchar column to lower length
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Change varchar length does not rewrite the table. It just check the constraint length against the entire table exactly as CHECK CONSTRAINT. If you increase length there is nothing to do, just next insert or updates will accept bigger length. If y...
What are the pros and cons of performing calculations in sql vs. in your application
...ext switches round trip. Yes: that is expensive. A "native" DBMS operation does all the hard work to minimise disk-I/O's (system calls) but manages to fetch more than one row per system call. Row at a time takes at least four system calls.
– wildplasser
Sep 22 ...
How to write a:hover in inline CSS?
... @Kato while that is a great link, and I really wish it worked, sadly it does not. Just to confirm, I tested using the syntax style="{color:green;} :hover { color: red; }" and firefox managed to color the link green, but ignored the hover. Chrome ignored both. Continued testing would be pretty poi...
How to check if a file is a valid image file?
... if he's really testing for "valid" images; the presence of a magic number doesn't guarantee that the file hasn't been truncated, for example.
– Ben Blank
May 20 '09 at 18:11
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What is the purpose of XORing a register with itself? [duplicate]
xor eax, eax will always set eax to zero, right? So, why does MSVC++ sometimes put it in my executable's code? Is it more efficient that mov eax, 0 ?
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Is quoting the value of url() really necessary?
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CSS 3 latest Editor's draft (may 2015) does not seem to allow quotes any more: dev.w3.org/csswg/css-syntax (check the url-token railroad schema) while current candidate recommendation (feb 2014) does: w3.org/TR/css-syntax-3 I suppose they want to promote usage of ...
Best way to iterate through a Perl array
...y.
In terms of readability: #1.
In terms of flexibility: #1/#4 and #5.
#2 does not support elements that are false. #2 and #3 are destructive.
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How to execute XPath one-liners from shell?
...ent! xmlstarlet sel -T -t -m '//element/@attribute' -v '.' -n filename.xml does exactly what I want!
– clacke
Mar 17 '13 at 14:49
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Remove scrollbar from iframe
... Thanks, but horizontal scroll only and still shows up in Firefox. Doesn't show up in Chrome nor IE. Also, CSS for scrollbar gets applied effectively only in IE, not FF nor Chrome (latter show default looking beige color/shades).
– Faith In Unseen Things
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