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How do I perform the SQL Join equivalent in MongoDB?
...rect. The new $lookup operator added to the aggregation pipeline is essentially identical to a left outer join:
https://docs.mongodb.org/master/reference/operator/aggregation/lookup/#pipe._S_lookup
From the docs:
{
$lookup:
{
from: <collection to join>,
localField: <...
Chaining multiple filter() in Django, is this a bug?
I always assumed that chaining multiple filter() calls in Django was always the same as collecting them in a single call.
4...
A more useful statusline in vim? [closed]
...nswered Mar 21 '11 at 15:57
TassosTassos
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When would you call java's thread.run() instead of thread.start()?
... the thread.run() code is invoked.
Executing thread.start() creates a new OS level thread wherein the run() method gets called.
In essence:
Single Threaded programming → Directly calling the run() method
Multi Threaded programming → Calling the start() method
Moreover, as other's ...
Relational table naming convention [closed]
...e theory.
Some of the wonderful things about Standards are:
they are all integrated with each other
they work together
they were written by minds greater than ours, so we do not have to
debate them.
The standard table name refers to each row in the table, which is used in the all verbiage, n...
multi-step registration process issues in asp.net mvc (split viewmodels, single model)
...
public string SomeOtherProperty { get; set; }
...
}
and so on. All those view models could be backed by a main wizard view model:
public class WizardViewModel
{
public Step1ViewModel Step1 { get; set; }
public Step2ViewModel Step2 { get; set; }
...
}
then you could have co...
What is the Difference Between Mercurial and Git?
...
I work on Mercurial, but fundamentally I believe both systems are equivalent. They both work with the same abstractions: a series of snapshots (changesets) which make up the history. Each changeset knows where it came from (the parent changeset) and can have ...
How can I change Eclipse theme?
...orthemes.org. The easiest way is to add this update URI to "Help -> Install New Software" and install it from there.
Eclipse Color Themes
This adds a "Color Theme" menu item under
Window -> Preferences -> Appearance
Where you can select from a large range of editor themes. My pref...
How do I avoid capturing self in blocks when implementing an API?
...ied inside the block (we're not doing that) but also they are not automatically retained when the block is retained (unless you are using ARC). If you do this, you must be sure that nothing else is going to try to execute the block after the MyDataProcessor instance is released. (Given the structure...
How to get a list of current open windows/process with Java?
... System.out.println(line); //<-- Parse data here.
}
input.close();
} catch (Exception err) {
err.printStackTrace();
}
If you are using Windows, then you should change the line: "Process p = Runtime.getRun..." etc... (3rd line), for one that looks like this:
Process p = Runtime....