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How to check if a table exists in a given schema
... (like OIDs) gets lost in translation from the system catalogs - which actually carry all information.
System catalogs
Your question was:
How to check whether a table exists?
SELECT EXISTS (
SELECT FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHE...
Calculate the median of a billion numbers
...bably too late if this had been an interview, but never mind:
Machine 1 shall be called the "control machine", and for the sake of argument either it starts with all the data, and sends it in equal parcels to the other 99 machines, or else the data starts evenly distributed between the machines, an...
Simple way to encode a string according to a password?
... to do much work to implement a proper encryption scheme however. First of all, don’t re-invent the cryptography wheel, use a trusted cryptography library to handle this for you. For Python 3, that trusted library is cryptography.
I also recommend that encryption and decryption applies to bytes; ...
Is it safe to use -1 to set all bits to true?
...s one:
unsigned long a = ~0u;
It won't necessarily store a pattern with all bits 1 into a. But it will first create a pattern with all bits 1 in an unsigned int, and then assign it to a. What happens when unsigned long has more bits is that not all of those are 1.
And consider this one, which wi...
Type hinting a collection of a specified type
...ntainers.
In other words, now you can do:
from typing import List
def my_func(l: List[int]):
pass
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Generate random numbers with a given (numerical) distribution
...> choices(population, weights)
4
The optional keyword-only argument k allows one to request more than one sample at once. This is valuable because there's some preparatory work that random.choices has to do every time it's called, prior to generating any samples; by generating many samples at o...
Install a .NET windows service without InstallUtil.exe
...My Sample Service", "Service that executes something",
_InstanceID,
// System.ServiceProcess.ServiceAccount.LocalService, // this is more secure, but only available in XP and above and WS-2003 and above
System.ServiceProcess.ServiceAccount.LocalSystem, // this is req...
Is there a read-only generic dictionary available in .NET?
...lt;TKey, TValue>
{
private readonly IDictionary<TKey, TValue> _dictionary;
public ReadOnlyDictionary()
{
_dictionary = new Dictionary<TKey, TValue>();
}
public ReadOnlyDictionary(IDictionary<TKey, TValue> dictionary)
{
_dictionary = dict...
Can't import my own modules in Python
...s
sys.path.append("..")
from myapp import SomeObject
though that is generally not recommended.
In general, if you want other people to use your Python package, you should use distutils to create a setup script. That way, anyone can install your package easily using a command like python setup.py ...
Match whitespace but not newlines
...ghteen horizontal ones which match \h. \s matches twenty-three characters
All whitespace characters are either vertical or horizontal with no overlap, but they are not proper subsets because \h also matches U+00A0 NO-BREAK SPACE, and \v also matches U+0085 NEXT LINE, neither of which are matched by...