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Multiprocessing - Pipe vs Queue
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A Pipe() can only have two endpoints.
A Queue() can have multiple producers and consumers.
When to use them
If you need more than two points to communicate, use a Queue().
If you need absolute performance, a Pipe() is much faster ...
What GRANT USAGE ON SCHEMA exactly do?
...table, but not the right to see it in the schema that contains it then you can't access the table.
The rights tests are done in order:
Do you have `USAGE` on the schema?
No: Reject access.
Yes: Do you also have the appropriate rights on the table?
No: Reject access.
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How exactly do Django content types work?
...orseen ways later down the road?" The reason why we ask this question is because this is what the Content Types framework does best: it creates generic relations between models. Blah blah, let's dive into some code and see what I mean.
# ourapp.models
from django.conf import settings
from django.db...
Different types of thread-safe Sets in Java
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1) The CopyOnWriteArraySet is a quite simple implementation - it basically has a list of elements in an array, and when changing the list, it copies the array. Iterations and other accesses which are running at this time continue with the old array, avoiding necessity of synchronization betwee...
Ignoring time zones altogether in Rails and PostgreSQL
...e date/time family, literally. It has typispreferred set in pg_type, which can be relevant:
Generating time series between two dates in PostgreSQL
Internal storage and epoch
Internally, timestamps occupy 8 bytes of storage on disk and in RAM. It is an integer value representing the count of micros...
std::vector versus std::array in C++
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std::vector is a template class that encapsulate a dynamic array1, stored in the heap, that grows and shrinks automatically if elements are added or removed. It provides all the hooks (begin(), end(), iterators, etc) that make it work fine with the rest of the STL...
What is the difference between active and passive FTP?
Can someone tell me what is the difference between active and passive FTP?
Which one is preferable?
5 Answers
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What is the correct answer for cout
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You can think of:
cout << a++ << a;
As:
std::operator<<(std::operator<<(std::cout, a++), a);
C++ guarantees that all side effects of previous evaluations will have been performed at sequence points. ...
What would cause an algorithm to have O(log log n) complexity?
This earlier question addresses some of the factors that might cause an algorithm to have O(log n) complexity.
2 Answers
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Possibility of duplicate Mongo ObjectId's being generated in two different collections?
...rivers are highly likely to be unique across collections. This is mainly because of the last 3 bytes of the ID, which for most drivers is generated via a static incrementing counter. That counter is collection-independent; it's global. The Java driver, for example, uses a randomly initialized, stati...