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Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc
...re looking for is part of the index used to find the data the server will fetch the data right there, if you do a select * it will most likely have to do what is called a bookmark lookup, which requires an extra scan to find the rest of the underlying data, which you may not even need.
...
RSA 算法是如何诞生的 - 创意 - 清泛网 - 专注C/C++及内核技术
RSA 算法是如何诞生的最近为了研究某个极其无聊的问题，读了一些公钥加密的历史，意外地发现这段历史竟然非常有趣。尤其是 RSA 算法的诞生过程，被很多书写得...最近为了研究某个极其无聊的问题，读了一些公钥加密的历史...
Simulating tremor (from e.g. Parkinson's Disease) with the mouse on a webpage?
...e tremor input.
Finally: for whatever controls you are programming (links, etc.):
capture click events, nudge them to the current "tremor" location based on the state of your tremor curves, and bounds-check your elements to see if the user has shaken out of the element intended, or possibly into an...
String, StringBuffer, and StringBuilder
...)
.toString()
Or
String s = new StringBuilder(100).appe..... etc. ...
// The difference is a size of 100 will be allocated upfront as fuzzy lollipop points out.
StringBuffer ( the syntax is exactly as with StringBuilder, the effects differ )
About
StringBuffer vs. StringBuilder ...
O2O江湖:2015大洗牌 2016 BAT等巨头将“肉搏” - 资讯 - 清泛网 - 专注C/C++及内核技术
...。新政一出，不禁让人质疑，这岂不是让本想解决出租车问题的专车沦为跟出租车一样的“二出租”？
移动会议专家创始人余德认为：“拥堵、安全等不是管理专车的遮羞布，牌照制才是出租领域的恶根。放弃既得利益、寻租...
Is the sizeof(some pointer) always equal to four?
...often a different size to normal pointers and also vary by platform, type, etc. Other than that +1.
– John5342
May 30 '13 at 12:59
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Long list of if statements in Java
...() implements Command {
void exec() {
// ...
}
}
// etc etc
then build a Map<String,Command> object and populate it with Command instances:
commandMap.put("A", new CommandA());
commandMap.put("B", new CommandB());
then you can replace your if/else if chain with:
co...
Pandas aggregate count distinct
...aframe, then grouped to ~2M
%time _=g.agg({"id": lambda x: x.nunique()})
CPU times: user 3min 3s, sys: 2.94 s, total: 3min 6s
Wall time: 3min 20s
%time _=g.agg({"id": pd.Series.nunique})
CPU times: user 3min 2s, sys: 2.44 s, total: 3min 4s
Wall time: 3min 18s
%time _=g.agg({"id": "nunique"})
CPU...
What's better at freeing memory with PHP: unset() or $var = null
...age collector will do it when it see fits - by intention as soon, as those CPU cycles aren't needed anyway, or as late as before the script would run out of memory, whatever occurs first.
If you are doing $whatever = null; then you are rewriting variable's data. You might get memory freed / shrunk f...
Exception thrown inside catch block - will it be caught again?
...{ } catch (Exception e){ System.err.println("In catch Exception: "+e.getClass()); }catch (IOException e){ System.err.println("In catch IOException: "+ e.getClass()); } and the code in try block generates IO Exception, Will it go to the immediate general Exception block or it will fly ove...