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Transaction isolation levels relation with locks on table
...s work on the same table T.
READ UNCOMMITTED - no lock on the table. You can read data in the table while writing on it. This means A writes data (uncommitted) and B can read this uncommitted data and use it (for any purpose). If A executes a rollback, B still has read the data and used it. This i...
Which kind of pointer do I use when?
...ost provided. I understand that C++11 now provides some of the types boost came up with, but not all of them.
4 Answers
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What is the purpose of setting a key in data.table?
...creasing order.
marks those columns as key columns by setting an attribute called sorted to DT.
The reordering is both fast (due to data.table's internal radix sorting) and memory efficient (only one extra column of type double is allocated).
When is setkey() required?
For grouping operations, s...
How do CDI and EJB compare? interact?
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CDI: it is about dependency injection. It means that you can inject interface implementation anywhere. This object can be anything, it can be not related to EJB. Here is an example of how to inject random generator using CDI. There is nothing about EJB. You are going to use CDI whe...
Why should we NOT use sys.setdefaultencoding(“utf-8”) in a py script?
... have seen few py scripts which use this at the top of the script. In what cases one should use it?
4 Answers
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Why does X[Y] join of data.tables not allow a full outer join, or a left join?
This is a bit of a philosophical question about data.table join syntax. I am finding more and more uses for data.tables, but still learning...
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REST API Token-based Authentication
I'm developing a REST API that requires authentication. Because the authentication itself occurs via an external webservice over HTTP, I reasoned that we would dispense tokens to avoid repeatedly calling the authentication service. Which brings me neatly to my first question:
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What's the difference between “groups” and “captures” in .NET regular expressions?
I'm a little fuzzy on what the difference between a "group" and a "capture" are when it comes to .NET's regular expression language. Consider the following C# code:
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Visual Studio or Resharper functionality for placement of using directives
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If you want to automatically fix not only this rule, but a bunch of the other ones also, it's better to update your StyleCop to the version 4.7 or higher, because it includes ReSharper plugin: stackoverflow.com/a/10884463/182371
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Why do we copy then move?
...ccept parameters.
Why aren't we taking an rvalue-reference to str?
Because that would make it impossible to pass lvalues, such as in:
std::string s = "Hello";
S obj(s); // s is an lvalue, this won't compile!
If S only had a constructor that accepts rvalues, the above would not compile.
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