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How important is the order of columns in indexes?
...eep them only on the leaf pages, for query coverability purposes. In other words, move them to INCLUDE. This becomes more important as the size of Least column increases. The idea is that this index can only benefit queries that specify MostSelective either as an exact value or a range, and that col...
What is the difference between RDF and OWL? [closed]
...amework) is that you can describe resources (anything) with sets of only 3 words (terms). At this level you don't care about how you are storing information, whether you have a string of 3 words, or a painting on a wall, or a table with 3 columns etc.
At this conceptual level the only thing that is...
Left Align Cells in UICollectionView
...e beginning of a new line which is not necessarily the case.
So in other words:
Most of the solutions suggested on this page work for some specific applications, but they don't work as expected in every situation.
AlignedCollectionViewFlowLayout
In order to address these issues I've created a...
DateTime vs DateTimeOffset
...lues, they are first normalized to zero offset before comparing. In other words, 2012-01-01T00:00:00+00:00 and 2012-01-01T02:00:00+02:00 refer to the same instantaneous moment, and are therefore equivalent.
If you are doing any unit testing and need to be certain of the offset, test both the DateTi...
Using .NET, how can you find the mime type of a file based on the file signature not the extension
...t the mimetype for .docx is "application/vnd.openxmlformats-officedocument.wordprocessingml.document". While this CAN be determined from a binary-only examination, it's probably not the most efficient way to do it, and in most cases you would have to read in more than the first 256 bytes.
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动态追踪（Dynamic Tracing）技术漫谈 - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
...为交互操作而生的，所以实现并不考虑生产安全性，也不怎么在乎性能损耗。一般它的性能损耗是极大的。同时 GDB 所基于的 ptrace 这种很古老的系统调用，其中的坑和问题也非常多。比如 ptrace 需要改变目标调试进程的父亲，还...
Difference between Python's Generators and Iterators
...he yield statement, in depth on my answer to "What does the “yield” keyword do?".
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Override Java System.currentTimeMillis for testing time sensitive code
...le, lock in the first moment of the earliest Christmas this year. in other words, when Santa and his reindeer make their first stop. The earliest time zone nowadays seems to be Pacific/Kiritimati at +14:00.
LocalDate ld = LocalDate.now( ZoneId.of( "America/Montreal" ) );
LocalDate xmasThisYear = Mon...
Stack vs heap allocation of structs in Go, and how they relate to garbage collection
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It's worth noting that the words "stack" and "heap" do not appear anywhere in the language spec. Your question is worded with "...is declared on the stack," and "...declared on the heap," but note that Go declaration syntax says nothing about stack or...
Lock, mutex, semaphore… what's the difference?
I've heard these words related to concurrent programming, but what's the difference between them?
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