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Retrieve only the queried element in an object array in MongoDB collection
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MongoDB 2.2's new $elemMatch projection operator provides another way to alter the returned document to contain only the first matched shapes element:
db.test.find(
{"shapes.color": "red"},
{_id: 0, shapes: {$elemMatch: {color: "red"}}});
Returns:
{"shapes" : [{"...
Using Core Data, iCloud and CloudKit for syncing and backup and how it works together
...ike this:
Core Data on its own, is completely local and does not automatically work with any of Apple's cloud services.
Core Data with iCloud enabled turns on syncing via iCloud. Any changes you save in Core Data are propagated to the cloud, and any changes made in the cloud are automatically down...
Why is git prompting me for a post-pull merge commit message?
...ing, but if you're using git out of the box on OSX it's probably a program called 'vi'. Type i to enter "INSERT" mode; type your message. You can then save and quit by hitting ESC and then typing :wq.
– Christopher
Dec 12 '13 at 22:02
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Different results with Java's digest versus external utilities
...e program code, you might think. The answer is that the emulator redirects calls to System32 folder to the SysWOW64 folder transparently so even if the folder is hard coded to the System32 folder (like C:\Windows\System32), the emulator will make sure that the SysWOW64 folder is used instead. So sam...
Difference between HEAD and master
... a branch. If you checkout a commit instead of a branch, you have what is called a "detached HEAD", you are no longer 'on a branch'. Being 'on a branch' means your HEAD is referencing a branch, and by definition you are on the most recent commit of that branch. Just because you have commit 'b54fe...
How do I make an Android EditView 'Done' button and hide the keyboard when clicked?
When the user clicks on the EditView , Android opens the keyboard so that user can write in the EditView .
17 Answers
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Effect of a Bitwise Operator on a Boolean in Java
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Specifically, & and ^ and | are the non-short-circuit logical boolean operators.
– Ken
Nov 12 '09 at 18:36
1...
Extract substring using regexp in plain bash
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Very clean, and avoids calls to external programs.
– Victor Zamanian
Aug 2 '17 at 8:20
9
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Grepping a huge file (80GB) any way to speed it up?
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@elcortegano: That's what's called I/O redirection. Basically, it reads input from the following filename. Similar to cat file.sql | parallel ... but avoids a UUOC. GNU parallel also has a way to read input from a file using parallel ... :::: file.sql. ...
How can I create a unique constraint on my column (SQL Server 2008 R2)?
...kground an unique index for the added constraint
create table Customer ( id int primary key identity (1,1) , name nvarchar(128) )
--Commands completed successfully.
sp_help Customer
---> index
--index_name index_description index_keys
--PK__Customer__3213E83FCC4A1DFA clustered, uniq...