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How do I force Postgres to use a particular index?
...om_page_cost = 1;
EXPLAIN <query>; # May use index scan now
You can restore the default value with SET random_page_cost = DEFAULT; again.
Background
Index scans require non-sequential disk page fetches. Postgres uses random_page_cost to estimate the cost of such non-sequential...
Understanding dispatch_async
...It takes about 4 or 5 seconds. It's been driving me crazy for several days now.
– GrandSteph
Sep 16 '14 at 15:26
@Gran...
What is tail call optimization?
...tyle. Many languages (Java, Python) doesn't provide TCO, then you have to know that a functional call costs memory... and the imperative style is prefered.
– mcoolive
Nov 7 '16 at 12:41
...
How to rename files and folder in Amazon S3?
... wrong comment has 15 upvotes. It should be deleted. Edit: And it was just now deleted. Nice.
– Doug S
Aug 24 '18 at 1:08
...
What is the difference between UTF-8 and Unicode?
...e the most common forms of this mapping; ISO-8859-1 and ISO-8859-15 (also known as ISO-Latin-1, latin1, and yes there are two different versions of the 8859 ISO standard as well).
But that's not enough when you want to represent characters from more than one language, so cramming all available char...
What's the difference between unit tests and integration tests? [duplicate]
...o I'd use a mock to mock the database and try to return a filtered list. I now understand that as being an integration test and something that will be picked up by QAs if the database returns New York when asked for cities in the UK. The unit test just tests that the round trip e.g. to the controlle...
Is the != check thread safe?
I know that compound operations such as i++ are not thread safe as they involve multiple operations.
8 Answers
...
Bare asterisk in function arguments?
...o", 3,5)
>>> test_args_kwargs(*args)
arg1: two
arg2: 3
arg3: 5
# now with **kwargs:
>>> kwargs = {"arg3": 3, "arg2": "two","arg1":5}
>>> test_args_kwargs(**kwargs)
arg1: 5
arg2: two
arg3: 3
So *args allows you to dynamically build a list of arguments that will be taken ...
How can I read large text files in Python, line by line, without loading it into memory?
... with two file handlers (one read, the other write) python was hanging and now it's fine! Thanks.
– Xelt
Apr 23 '19 at 13:37
...
Why do we need tuples in Python (or any immutable data type)?
...ding a tuple is over 7.6 times faster than building the equivalent list -- now you can't say you've "never seen a noticeable difference" any more, unless your definition of "noticeable" is truly peculiar...
– Alex Martelli
Feb 1 '10 at 4:35
...