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Is there any performance gain in indexing a boolean field?
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It can make a difference. Just cut the execution time in half of a query just by adding an index, and writes are rare and cheap enough that we don't really care about the penalty. As with everything, don't assume, measure (also because databases don't always actually behave...
What are rvalues, lvalues, xvalues, glvalues, and prvalues?
In C++03, an expression is either an rvalue or an lvalue .
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程序员之网络安全系列（六）：动态密码 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...让他在一定时间有效就可以了，这就是OTP.
动态口令 (One Time Password)
动态密码： 一个OTP(One Time Password) 是一个密码仅用于一次登录会话或者交易，使用过后，这个密码就无效了。
静态密码的问题：
容易被破解
容易被猜测
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Is there a command to list SVN conflicts?
Does anyone know an SVN command to list current conflicts between the repo and the working copy?
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Singleton with Arguments in Java
... singleton is performing is recurring, and with different parameters every time, you might as well pass the parameters to the main method being executed:
SingletonObj singleton = SingletonObj.getInstance();
singleton.doSomething(paramA, paramB); // pass parameters on execution
In any case, instan...
Is there a better Windows Console Window? [closed]
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As a long-time user of Console 2, I switched to ConEmu recently and have not looked back. This is so much better than anything that has come before it almost defies belief. Plus is is being rapidly developed (thanks Maximus!) with juic...
Chaining multiple MapReduce jobs in Hadoop
...nally via the Cascading planner and Flow classes.
This way you spend your time focusing on your problem, not on the mechanics of managing Hadoop jobs etc. You can even layer different languages on top (like clojure or jruby) to even further simplify your development and applications. http://www.cas...
Exporting APK from eclipse (ADT) silently crashes
Every time I try to export an APK from Eclipse (tried Juno and Indigo) on Mac, eclipse crashes after a few seconds
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Disable same origin policy in Chrome
...er, Is it possible to run Chrome with and without web security at the same time?.
Basically, by running the following command (or creating a shortcut with it and opening Chrome through that)
chrome.exe --user-data-dir="C:/Chrome dev session" --disable-web-security
you can open a new "insecure" i...
SQL to find the number of distinct values in a column
I can select all the distinct values in a column in the following ways:
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