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postgresql COUNT(DISTINCT …) very slow
...
You can use this:
SELECT COUNT(*) FROM (SELECT DISTINCT column_name FROM table_name) AS temp;
This is much faster than:
COUNT(DISTINCT column_name)
share
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What is the HTML tabindex attribute?
...ments support the tabindex attribute: anchor, area, button, input, object, select, and textarea. But the HTML5 spec, with accessibility in mind, allows all elements to be assigned tabindex.
--
For example
<ul tabindex="-1">
<li tabindex="1"></li>
<li tabindex="2"><...
How to append a newline to StringBuilder
... edited Mar 15 '19 at 16:20
Charles Giguere
4711 silver badge99 bronze badges
answered Dec 3 '15 at 18:00
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解决：ORA-00054:资源正忙,要求指定NOWAIT - 数据库(内核) - 清泛网 - 专注...
...删除
1：找出所有被锁的对象，定位出哪个回话占用
select l.session_id,o.owner,o.object_name from v$locked_object l,dba_objects o where l.object_id=o.object_id
结果：
session_id owner object_name
158 SA TEST_1
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对比想要创建的索引，定位哪些会话需要...
Sort a list from another list IDs
...; source,
IEnumerable<TId> order,
Func<T, TId> idSelector)
{
var lookup = source.ToDictionary(idSelector, t => t);
foreach (var id in order)
{
yield return lookup[id];
}
}
Is a generic extension for what you want.
You could use the extension li...
If table exists drop table then create it, if it does not exist just create it
...up the old table,
obviously.
Wrapping all statements with something like SELECT GET_LOCK('__upgrade', -1); ... DO RELEASE_LOCK('__upgrade'); allows to just invoke all statements sequentially without error checking, but I don't think it's a good idea: complexity increases and locking functions in M...
Use gulp to select and move directories and their files
... },
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true,enableSnippets:true
});
}
});
...
Why do some scripts omit the closing PHP tag, '?>'? [duplicate]
...mitting the closing tag is just one solution for avoiding blanks and other characters at the end of file. For example any char which is accidentally added behind the closing tag would trigger an error when trying to modify header info later.
Removing the closing tag is kind of "good practice" refer...
Capybara Ambiguity Resolution
...t
So it's adviced to choose another, less ambiguous locator: for example select element by id, class or other css/xpath locator so that only one element will match it.
As a note here are some locators that I usually consider useful when resolving ambiguity:
find('ul > li:first-child')
It'...
How to get share counts using graph API
...e fql end-point (the link_stat table):
https://graph.facebook.com/fql?q=SELECT url, normalized_url, share_count, like_count, comment_count, total_count,commentsbox_count, comments_fbid, click_count FROM link_stat WHERE url='http://www.google.com'
total_count is the number that shows in the Like...