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how to exclude null values in array_agg like in string_agg using postgres?
...t names, I get my names separated by commas, but in case there is a null value, that null is also taken as a name in the aggregate. For example :
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How to explain callbacks in plain english? How are they different from calling one function from ano
...context from the calling function? How can their power be explained to a novice programmer?
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FixedThreadPool vs CachedThreadPool: the lesser of two evils
I have a program that spawns threads (~5-150) which perform a bunch of tasks. Originally, I used a FixedThreadPool because this similar question suggested they were better suited for longer lived tasks and with my very limited knowledge of multithreading, I considered the average life of the thr...
How to use '-prune' option of 'find' in sh?
I don't quite understand the example given from the man find , can anyone give me some examples and explanations? Can I combine regular expression in it?
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Why do we use arrays instead of other data structures?
As I was programming, I haven't seen an instance where an array is better for storing information than another form thereof. I had indeed figured the added "features" in programming languages had improved upon this and by that replaced them. I see now that they aren't replaced but rather given new ...
What is the purpose of Flask's context stacks?
I've been using the request/application context for some time without fully understanding how it works or why it was designed the way it was. What is the purpose of the "stack" when it comes to the request or application context? Are these two separate stacks, or are they both part of one stack? Is ...
Node.js and CPU intensive requests
I've started tinkering with Node.js HTTP server and really like to write server side Javascript but something is keeping me from starting to use Node.js for my web application.
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How can I plot with 2 different y-axes?
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How would you implement an LRU cache in Java?
... that I want to implement my own using just the SDK (learning by doing). Given that the cache will be used in a multithreaded environment, which datastructures would you use? I've already implemented one using LinkedHashMap and Collections#synchronizedMap , but I'm curious if any of the new concu...
What's the best way to send a signal to all members of a process group?
I want to kill a whole process tree. What is the best way to do this using any common scripting languages? I am looking for a simple solution.
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