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Why does X[Y] join of data.tables not allow a full outer join, or a left join?
...bit of a philosophical question about data.table join syntax. I am finding more and more uses for data.tables, but still learning...
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Find all records which have a count of an association greater than zero
...up clause, the code above will return duplicate projects for projects with more than one vacancies. To remove the duplicates, use
Project.joins(:vacancies).group('projects.id')
UPDATE:
As pointed out by @Tolsee, you can also use distinct.
Project.joins(:vacancies).distinct
As an example
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How to initialize a List to a given size (as opposed to capacity)?
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I can't say I need this very often - could you give more details as to why you want this? I'd probably put it as a static method in a helper class:
public static class Lists
{
public static List<T> RepeatedDefault<T>(int count)
{
return Repeated(de...
Why use the INCLUDE clause when creating an index?
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@gbn, would you mind explaining this sentence in more detail, and explain why it means that the include clause is not useful for sorting, etc: "The INCLUDE clause adds the data at the lowest/leaf level, rather than in the index tree. This makes the index smaller because it'...
Why malloc+memset is slower than calloc?
...) will first try to get 16 bytes out of one of its pools, and then ask for more memory from the kernel when the pool runs dry. However, since the program you're asking about is allocating for a large amount of memory at once, malloc() and calloc() will just ask for that memory directly from the ker...
Why we should not use protected static in java
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It's more a stylistic thing than a direct problem. It suggests that you haven't properly thought through what is going on with the class.
Think about what static means:
This variable exists at class level, it does not exist s...
When should I use a struct instead of a class?
...copy than 16-byte structs, there are many cases where large structs may be more efficient than large class objects, and where the relative advantage of structs grows with the size of the struct.
– supercat
Jan 2 '13 at 16:12
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What are metaclasses in Python?
... define the type of a class, not just a factory for it, so you can do much more with them. You can, for instance, define normal methods on the metaclass. These metaclass-methods are like classmethods in that they can be called on the class without an instance, but they are also not like classmethods...
How to generate a core dump in Linux on a segmentation fault?
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This link goes deeper and gives some more options to enable generation of core dumps in linux. The only drawback is that some commands/settings are left unexplained.
– Salsa
Aug 31 '11 at 19:45
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