大约有 47,000 项符合查询结果（耗时：0.0667秒） [XML]
SQL Joins Vs SQL Subqueries (Performance)?
...PECT the first query to be quicker, mainly because you have an equivalence and an explicit JOIN. In my experience IN is a very slow operator, since SQL normally evaluates it as a series of WHERE clauses separated by "OR" (WHERE x=Y OR x=Z OR...).
As with ALL THINGS SQL though, your mileage may va...
What should be the values of GOPATH and GOROOT?
...ing. On Plan 9, the value is a list.
GOPATH must be set to get, build and install packages outside the
standard Go tree.
GOROOT is discussed in the installation instructions:
The Go binary distributions assume they will be installed in
/usr/local/go (or c:\Go under Windows), but it is...
How to implement Android Pull-to-Refresh
In Android applications such as Twitter (official app), when you encounter a ListView, you can pull it down (and it will bounce back when released) to refresh the content.
...
Pass all variables from one shell script to another?
...E) before executing the 2nd script.
Source the 2nd script, i.e. . test2.sh and it will run in the same shell. This would let you share more complex variables like arrays easily, but also means that the other script could modify variables in the source shell.
UPDATE:
To use export to set an enviro...
Is PHP's count() function O(1) or O(n) for arrays?
...unt the all the elements of a PHP array, or is this value cached somewhere and just gets retrieved?
3 Answers
...
From Arraylist to Array
... zero-length array is created, then the real-size array is created, filled and returned. So, if since you know the needed size (from list.size()) you should create array that is big enough to put all elements. In this case it is not re-allocated.
...
Is there any significant difference between using if/else and switch-case in C#?
... (unlike many other languages) also allows to switch on string constants - and this works a bit differently. It's obviously not practical to build jump tables for strings of arbitrary lengths, so most often such switch will be compiled into stack of IFs.
But if number of conditions is big enough t...
Difference between modes a, a+, w, w+, and r+ in built-in open function?
...tion, what is the exact difference between the modes w , a , w+ , a+ , and r+ ?
6 Answers
...
Mongoose indexing in production code
Per the Mongoose documentation for MongooseJS and MongoDB / Node.js :
3 Answers
...
Are Java static calls more or less expensive than non-static calls?
...ful to know they are at least as fast, if not faster than instance methods and should not be ruled out on a performance basis.
– Will
Oct 21 '17 at 13:11
2
...