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mongodb count num of distinct values per field/key
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MongoDB has a distinct command which returns an array of distinct values for a field; you can check the length of the array for a count.
There is a shell db.collection.distinct() helper as well:
> db.countries.distinct('country');
[ "Spain", "Engl...
“find: paths must precede expression:” How do I specify a recursive search that also finds files in
... quotes around your file expression -- these will stop the shell (bash) expanding your wildcards.
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Linq to SQL how to do “where [column] in (list of values)”
I have a function where I get a list of ids, and I need to return the a list matching a description that is associated with the id. E.g.:
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Get current batchfile directory
Firstly, I saw this topic but I couldn't understand that.
4 Answers
4
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Is there a faster/shorter way to initialize variables in a Rust struct?
...default. You could define a new type that implements a default value of -1 and use that instead of i64 in your struct. (I haven't tested that, but it should work).
However, I'd suggest to slightly change your data structure and use Option<i64> instead of i64. I don't know the context of your ...
Do HTML WebSockets maintain an open connection for each client? Does this scale?
... line of communication with the server. I'm just wondering how that scales and how many open WebSocket connections a server can handle. Maybe leaving those connections open isn't a problem in reality, but it feels like it is.
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Handling warning for possible multiple enumeration of IEnumerable
... you wish to enumerate.
I can change the objects parameter to be List and then avoid the possible multiple enumeration but then I don't get the highest object that I can handle.
The goal of taking the highest object is noble, but it leaves room for too many assumptions. Do you really want som...
How to use NSCache
... into account:
// Your cache should have a lifetime beyond the method or handful of methods
// that use it. For example, you could make it a field of your application
// delegate, or of your view controller, or something like that. Up to you.
NSCache *myCache = ...;
NSAssert(myCache != nil, @"cache...
Can git automatically switch between spaces and tabs?
...butes which contains:
*.py filter=tabspace
Linux/Unix
Now run the commands:
git config --global filter.tabspace.smudge 'unexpand --tabs=4 --first-only'
git config --global filter.tabspace.clean 'expand --tabs=4 --initial'
OS X
First install coreutils with brew:
brew install coreutils
Now...
Simple way to copy or clone a DataRow?
... to make a clone of a DataRow. Kind of like taking a snapshot of that Row and saving it. The values of original Row are then free to change but we still have another saved copy which doesn't change. Is this the correct way to do it?
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