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How to create index on JSON field in Postgres?
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Found:
CREATE TABLE publishers(id INT, info JSON);
CREATE INDEX ON publishers((info->>'name'));
As stated in the comments, the subtle difference here is ->> instead of ->. The former one returns the value as text, the latter as a JSON object...
Why implement interface explicitly?
So, what exactly is a good use case for implementing an interface explicitly?
11 Answers
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How do you UrlEncode without using System.Web?
...ne Breaks
All of them listed here (other than HttpUtility.HtmlEncode) will convert "\n\r" into %0a%0d or %0A%0D
Please feel free to edit this and add new characters to my test string, or leave them in the comments and I'll edit it.
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Good Hash Function for Strings
...it more likely to generate unique hashes) So you could do something like:
int hash = 7;
for (int i = 0; i < strlen; i++) {
hash = hash*31 + charAt(i);
}
share
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improve this answer
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IE9 border-radius and background gradient bleeding
...nal elements.
I grabbed a random 20x20 gradient PNG via a web search, and converted it into a data URI using an online tool. The resulting data URI is smaller than the CSS code for all that SVG mess, much less the SVG itself! (You could apply this conditionally to IE9 only using conditional style...
How do I get the MIN() of two fields in Postgres?
...alue from a list of any number of expressions. The expressions must all be convertible to a common data type, which will be the type of the result (see Section 10.5 for details). NULL values in the list are ignored. The result will be NULL only if all the expressions evaluate to NULL.
Note that...
NSLog the method name with Objective-C in iPhone
... Method calls like [self doSomething:arg1 somethingElse:arg2] get converted into the C function call objc_msgSend(self, "doSomething:somethingElse:, arg1, arg2);. The second parameter of objc_msgSend() takes a char*. Remember that because the Objective-C runtime is dynamic, it's actually us...
Java: Static vs inner class [duplicate]
...stance.
See this example
class A
{
class B
{
// static int x; not allowed here
}
static class C
{
static int x; // allowed here
}
}
class Test
{
public static void main(String… str)
{
A a = new A();
// Non-Static Inner Class
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How to launch an Activity from another Application in Android
...ed package from my Android application. I assume that it is possible using intents, but I didn't find a way of doing it. Is there a link, where to find the information?
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Input and Output binary streams using JERSEY?
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This consumes all bytes into memory, which means large files could bring down the server. The purpose of streaming is to avoid consuming all bytes into memory.
– Robert Christian
Jan 15 '16 at 0:34
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