大约有 40,000 项符合查询结果（耗时：0.0604秒） [XML]
postgresql COUNT(DISTINCT …) very slow
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I found this thread on www.postgresql.org which discusses the same thing: link. One of the replies (by Jeff Janes) says that COUNT(DISTINCT()) sorts the table to do its work instead of using hash.
– Ankur
Dec ...
How to check if a file is empty in Bash?
I have a file called diff.txt. Want to check if it is empty. Did something like this but couldn't get it working.
10 Answe...
Scala best way of turning a Collection into a Map-by-key?
If I have a collection c of type T and there is a property p on T (of type P , say), what is the best way to do a map-by-extracting-key ?
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What is the difference between “int” and “uint” / “long” and “ulong”?
...d briefly looked at 6502 shudder
A brief google search shows this:
https://www.tutorialspoint.com/cprogramming/c_data_types.htm
This is also good info:
https://docs.oracle.com/cd/E19620-01/805-3024/lp64-1/index.html
use int if you really don't care how large your bits are; it can change.
Use size_t ...
How do you loop in a Windows batch file?
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FOR %%A IN (list) DO command parameters
list is a list of any elements, separated by either spaces, commas or semicolons.
command can be any internal or external command, batch file or even - in OS/2 and NT - a list of commands
paramet...
How to clear the interpreter console?
...lly keep a console window open with the Python interpreter running to test commands, dir() stuff, help() stuff , etc.
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Is there a JSON equivalent of XQuery/XPath?
When searching for items in complex JSON arrays and hashes, like:
15 Answers
15
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OSX - How to auto Close Terminal window after the “exit” command executed.
... You can use the link for more and step wise step info cnet.com/news/terminal-tip-close-windows-after-clean-exit
– Krishan Kumar Mourya
Jan 12 '18 at 7:37
1
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What is the meaning of #XXX in code comments?
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XXX in a comment is usually a heads-up. It could be:
Something that's not implemented completely correctly.
Something that should be fixed later on.
Highlighting a possible problem spot.
Something you're not sure about, a question.
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Mongo interface [closed]
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Official List from MongoDB
http://www.mongodb.org/display/DOCS/Admin+UIs
Web Based
For PHP, I'd recommend Rock Mongo. Solid, lots of great features, easy setup.
http://rockmongo.com/
If you don't want to install anything ... you can use MongoHQ's web inte...