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Why doesn't the example compile, aka how does (co-, contra-, and in-) variance work?
...ranslating their example to use your construct:
val x = new Slot[String]("test") // Make a slot
val y: Slot[Any] = x // Ok, 'cause String is a subtype of Any
y.set(new Rational(1, 2)) // Works, but now x.get() will blow up
If you feel I'm not understanding your question (a dis...
What is the most efficient/elegant way to parse a flat table into a tree?
...BLE AS m JOIN MyTree AS t ON m.ParentId = t.Id
)
SELECT * FROM MyTree;
I tested recursive queries in MySQL 8.0 in my presentation Recursive Query Throwdown in 2017.
Below is my original answer from 2008:
There are several ways to store tree-structured data in a relational database. What you s...
Difference between git checkout --track origin/branch and git checkout -b branch origin/branch
...
@Green The test you do is with origin/new-branch instead of origin/branch. Are you aware of that?
– Robert Siemer
Apr 13 '19 at 22:02
...
Rebasing and what does one mean by rebasing pushed commits
...ID (in this case, a, b, c, and d). You'll notice that d is currently the latest commit (or HEAD) of the master branch.
Here, we have two branches: master and my-branch. You can see that master and my-branch both contain commits a and b, but then they start to diverge: master contains c and d, whil...
What's the difference between a catalog and a schema in a relational database?
...per host computer (or virtual OS). Multiple clusters is commonly done, for testing and deploying new versions of Postgres (ex: 9.0, 9.1, 9.2, 9.3, 9.4, 9.5).
If you did have multiple clusters, imagine the diagram above duplicated.
Different port numbers allow the multiple clusters to live side-by...
Convert JavaScript string in dot notation into an object reference
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@Mr.B. the latest version of Lodash has a third, optional, argument for defaultValue. The _.get() method returns the default value if _.get() resolves to undefined, so set it to whatever you want and watch for the value you set.
...
How important is the order of columns in indexes?
...tioned in one Answer.
So, what order should be used?
Start with column(s) tested with =, in any order.
Then tack on one range column.
For example, the very-low selectivity column must come first in this:
WHERE deleted = 0 AND the_datetime > NOW() - INTERVAL 7 DAY
INDEX(deleted, the_datetime)
...
Measure time in Linux - time vs clock vs getrusage vs clock_gettime vs gettimeofday vs timespec_get?
... and does not wrap around. The precision on my system is 1 µs, but I also tested it on a Linux system (Red Hat 4.1.2-48 with GCC 4.1.2) and there the precision was only 1 ms.
gettimeofday() returns the wall-clock time with (nominally) µs precision. On my system this clock does seem to have µs pre...
How do arrays in C# partially implement IList?
...
// Implicit interface implementation
public void M2() {}
}
class Test
{
static void Main()
{
Foo foo = new Foo();
foo.M1(); // Compile-time failure
foo.M2(); // Fine
IFoo ifoo = foo;
ifoo.M1(); // Fine
ifoo.M2(); // Fine
}
}...
How do you track record relations in NoSQL?
...you see it NoSQL != NoSQL. You need to look at specific implementation and test it for yourself.
Mentioned before Column stores look like good fit for relations.. but it all depends on your A and C and P needs;) If you do not need A and you have less than Peta bytes just leave it, go ahead with MyS...