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How to express a NOT IN query with ActiveRecord/Rails?
...rums, lambda { |forums| { :conditions => ['forum_id not in (?)', forums.select(&:id).join(',')] }
# in your controller
Topic.not_in_forums(@forums)
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When are you truly forced to use UUID as part of the design?
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@Chamnap I wrote UUIDTools. UUIDs can be converted to an integer or their raw byte form, and would be substantially smaller as a binary.
– Bob Aman
Jun 10 '12 at 14:21
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内存优化总结:ptmalloc、tcmalloc和jemalloc - 操作系统(内核) - 清泛网 - ...
... 总共32个vcpu。 16个table，每个5M row。
OLTP_RO测试包含5个select查询：select_ranges, select_order_ranges, select_distinct_ranges, select_sum_ranges,
可以看到在多核心或者多线程的场景下， jemalloc和tcmalloc带来的tps增加非常明显。
参考资料
glibc...
How do you perform a left outer join using linq extension methods
...=> bar.Foo_Id,
(x,y) => new { Foo = x, Bars = y })
.SelectMany(
x => x.Bars.DefaultIfEmpty(),
(x,y) => new { Foo=x.Foo, Bar=y});
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MySQL query to get column names?
...a virtual database. Specifically the INFORMATION_SCHEMA.COLUMNS table...
SELECT `COLUMN_NAME`
FROM `INFORMATION_SCHEMA`.`COLUMNS`
WHERE `TABLE_SCHEMA`='yourdatabasename'
AND `TABLE_NAME`='yourtablename';
It's VERY powerful, and can give you TONS of information without need to parse text (...
Sublime 3 - Set Key map for function Goto Definition
..."count": 1,
"modifiers": ["ctrl"],
"press_command": "drag_select",
"command": "goto_definition"
}
]
You can change modifiers key as you like.
Since Ctrl-button1 on Windows and Linux is used for multiple selections, adding a second modifier key like Alt might be a go...
Find an element in DOM based on an attribute value
...ears the landscape has changed drastically. You can now reliably use querySelector and querySelectorAll, see Wojtek's answer for how to do this.
There's no need for a jQuery dependency now. If you're using jQuery, great...if you're not, you need not rely it on just for selecting elements by att...
Intellij IDEA, format all code in a project
...can use the shortcut Ctrl+ALT+L (Windows/Linux) or ⌥⌘+L (MAC OS X) and select the Rearrange entries option to reformat the code in the current file or reformat a module or directory (after selecting more than one file).
You can also Right-click a module, file or directory from the context menu ...
how to edit .csproj file
...these simple steps:
Right click on your project in solution explorer and select Unload Project
Right click on the project (tagged as unavailable in solution explorer) and click "Edit yourproj.csproj". This will open up your CSPROJ file for editing.
After making any changes you want, save and clos...
IntelliJ not recognizing a particular file correctly, instead its stuck as a text file
...te the file, I encountered the error 'Unable to parse template "Interface" Selected class file name mapped to not java'. Couldn't find that error message anywhere in Google, so posting it here in case someone else needs it.
– Knetic
Sep 22 '14 at 17:08
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