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What does Redis do when it runs out of memory?
... time finding the answer. How does Redis 2.0 handle running out of maximum allocated memory? How does it decide which data to remove or which data to keep in memory?
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Can dplyr package be used for conditional mutating?
...and the conditions (except for the default value of NA at the end) are mutually exclusive, as is the case in the question, then we can use an arithmetic expression such that each term is multiplied by the desired result using na_if at the end to replace 0 with NA.
df %>%
mutate(g = 2 * (a == 2 ...
How do I reset a sequence in Oracle?
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alter sequence serial restart start with 1;
This feature was officially added in 18c but is unofficially available since 12.1.
It is arguably safe to use this undocumented feature in 12.1. Even though the syntax is not included in the official documentation, it is generated by the Oracle pa...
UIButton Long Press Event
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UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
[self.button addGestureRecognizer:longPress];
[longPress release];
And then implement the method that handles the gesture
- (void)longPress:(UILongPressGestureRecog...
Oracle SQL: Update a table with data from another table
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This is called a correlated update
UPDATE table1 t1
SET (name, desc) = (SELECT t2.name, t2.desc
FROM table2 t2
WHERE t1.id = t2.id)
WHERE EXISTS (
SELECT 1
FROM table2 t2...
How do I create delegates in Objective-C?
...ign it as the web view's delegate:
MyClass *instanceOfMyClass = [[MyClass alloc] init];
myWebView.delegate = instanceOfMyClass;
On the UIWebView side, it probably has code similar to this to see if the delegate responds to the webViewDidStartLoad: message using respondsToSelector: and send it if ...
Printing a variable memory address in swift
...er was quite old. Many of the methods it describes no longer work. Specifically .core cannot be accessed anymore.
However @drew's answer is correct and simple:
This is now part of the standard library: unsafeAddressOf.
So the answer to your questions is:
println(" str value \(str) has addre...
Comparing two dataframes and getting the differences
...df2, works only for dataframes with identical rows and columns. In fact, all dataframes axes are compared with _indexed_same method, and exception is raised if differences found, even in columns/indices order.
If I got you right, you want not to find changes, but symmetric difference. For that, o...
C# code to validate email address
...e-mail addresses are more forgiving than you might first assume. These are all perfectly valid forms:
cog@wheel
"cogwheel the orange"@example.com
123@$.xyz
For most use cases, a false "invalid" is much worse for your users and future proofing than a false "valid". Here's an article that used to ...
How to prevent a background process from being stopped after closing SSH client in Linux
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I would recommend using GNU Screen. It allows you to disconnect from the server while all of your processes continue to run. I don't know how I lived without it before I knew it existed.
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