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postgresql COUNT(DISTINCT …) very slow
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I found this thread on www.postgresql.org which discusses the same thing: link. One of the replies (by Jeff Janes) says that COUNT(DISTINCT()) sorts the table to do its work instead of using hash.
– Ankur
Dec ...
Is it possible to cache POST methods in HTTP?
...ces:
https://tools.ietf.org/html/rfc2616#section-13 HTTP/1.1 RFC
https://www.mnot.net/blog/2012/09/24/caching_POST
Demonstration of Browser Behavior
Given the following example JavaScript application (index.js):
const express = require('express')
const app = express()
let count = 0
app
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How to search contents of multiple pdf files?
...e contents of PDF files in a directory/subdirectory? I am looking for some command line tools. It seems that grep can't search PDF files.
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Can table columns with a Foreign Key be NULL?
...NTO child (id, parent_id) VALUES (1, NULL);
-- Query OK, 1 row affected (0.01 sec)
INSERT INTO child (id, parent_id) VALUES (2, 1);
-- ERROR 1452 (23000): Cannot add or update a child row: a foreign key
-- constraint fails (`t/child`, CONSTRAINT `child_ibfk_1` FOREIGN KEY
-- (`parent_id`) REFERE...
How to format a phone number with jQuery
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54
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How should the ViewModel close the form?
... edited May 23 '17 at 11:47
Community♦
111 silver badge
answered Jul 25 '10 at 14:06
Joe WhiteJoe White
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Does have to be in the of an HTML document?
...date it seems that only Firefox supports the scoped attribute, see caniuse.com/#feat=style-scoped.
– Jaime Hablutzel
Oct 15 '15 at 23:18
2
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How do I find the MySQL my.cnf location
Is there a MySQL command to locate the my.cnf configuration file, similar to how PHP's phpinfo() locates its php.ini ?
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How to iterate through SparseArray?
...ueAt(i);
– Florian
Feb 15 '13 at 17:01
27
valueAt(i) is faster than get(key), because valueAt(i) ...
Objective-C: Where to remove observer for NSNotification?
...eed the notifications". This is obviously not a satisfying answer.
I'd recommend, that you add a call [notificationCenter removeObserver: self] in method dealloc of those classes, which you intend to use as observers, as it is the last chance to unregister an observer cleanly. This will, however, ...