大约有 40,000 项符合查询结果（耗时：0.0357秒） [XML]
Surrogate vs. natural/business keys [closed]
... for a logical primary key. They are both essentially just non-null unique index constraints.
– dkretz
Feb 12 '09 at 22:11
1
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Expand/collapse section in UITableView in iOS
...set up a cell to LOOK like a header, and setup the tableView:didSelectRowAtIndexPath to manually expand or collapse the section it is in.
I'd store an array of booleans corresponding the the "expended" value of each of your sections. Then you could have the tableView:didSelectRowAtIndexPath on each...
Read/write to Windows registry using Java
...o[0]; // count
int maxlen = info[3]; // value length max
for(int index=0; index<count; index++) {
byte[] name = (byte[]) regEnumValue.invoke(root, new Object[] {
new Integer
(handles[0]), new Integer(index), new Integer(maxlen + 1)});
String value = re...
Fastest way to check if a value exists in a list
...value exists in a list (a list with millions of values in it) and what its index is?
13 Answers
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Is there a performance difference between CTE , Sub-Query, Temporary Table or Table Variable?
...hints, restructure the query, update statistics, use temporary tables, add indexes, and so on to get better performance.
As for your question. The performance of CTEs and subqueries should, in theory, be the same since both provide the same information to the query optimizer. One difference is th...
What does the line “#!/bin/sh” mean in a UNIX shell script?
...
It's called a shebang, and tells the parent shell which interpreter should be used to execute the script.
e.g.
#!/usr/bin/perl <--perl script'
#!/usr/bin/php <-- php script
#!/bin/false <--- do-nothing script, because ...
Sorting 1 million 8-decimal-digit numbers with 1 MB of RAM
...levant tests already available:
http://www.theeggeadventure.com/wikimedia/index.php/Java_Data_Compression
"I ran a test to compress one million consecutive integers using
various forms of compression. The results are as follows:"
None 4000027
Deflate 2006803
Filtered 1391833
BZip2 4...
Cross-browser testing: All major browsers on ONE machine
...of IE/Safari on a single Windows machine.
Download: http://sandboxie.com/index.php?DownloadSandboxie
Patch: The extended version is required to enable multiple sandboxes at a time. Pay them or visit YouTube.
Running multiple IE/Safari versions simultaneously requires the extended version. If you d...
Format bytes to kilobytes, megabytes, gigabytes
... return round($bytes, $precision) . ' ' . $units[$pow];
}
(Taken from php.net, there are many other examples there, but I like this one best :-)
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boost::flat_map and its performance compared to map and unordered_map
... flat land, whereas a standard unordered map just has to recreate the hash index, while the allocated data stays where it is. The disadvantage of course is that the memory is fragmented like hell.
The criterion of a rehash in an open address hash map is when the capacity exceeds the size of the buc...