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How does Amazon RDS backup/snapshot actually work?
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We also run several RDS instances, in addition to MySQL on some machines that we manage ourselves. I can't comment specifically, as I'm not an Amazon engineer, but several things I've learned that might explain what you're seeing:
Although Amazon does not share the backend...
Improve INSERT-per-second performance of SQLite
...com/rdpoor/CreateOrUpdate
which bulk loads an array of ActiveRecords into MySQL, SQLite or PostgreSQL databases. It includes an option to ignore existing records, overwrite them or raise an error. My rudimentary benchmarks show a 10x speed improvement compared to sequential writes -- YMMV.
I'm usi...
Ruby convert Object to Hash
...> 15.95 }}
If you need a hash that's stored in the object use as_json(root: false). I think by default root will be false. For more info refer official ruby guide
http://api.rubyonrails.org/classes/ActiveModel/Serializers/JSON.html#method-i-as_json
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Primary key or Unique index?
...hen it tries to insert the value 1 into this column for a second time.
In MySQL a unique constraint allows multiple NULLs.
It is possible to make a unique index on mutiple columns.
Primary key versus unique index
Things that are the same:
A primary key implies a unique index.
Things that are...
“Auto Layout still required after executing -layoutSubviews” with UITableViewCell subclass
.... I think the problem is the custom view that UITableViewCell uses as its root view can't use auto layout because it overrides layoutSubviews (so when you try to add constraints to the root view, it will fail)
– borrrden
Oct 18 '12 at 5:29
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Django FileField with upload_to determined at runtime
...g to set up my uploads so that if user joe uploads a file it goes to MEDIA_ROOT/joe as opposed to having everyone's files go to MEDIA_ROOT. The problem is I don't know how to define this in the model. Here is how it currently looks:
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Python - Create a list with initial capacity
... 0.0098
Conclusion. It barely matters.
Premature optimization is the root of all evil.
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Sublime Text 3能用支持的插件推荐 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...方法不管用，可以看看我之前写的一篇文章，Sublime text 3如何安装package control办法。
此外，安装sublime text 3的插件还可以在github上下载源文件，解压后改名放到
C:\Users\Mr.DenGo(你的电脑名)\AppData\Roaming\Sublime Text 3\Packages 中
重启su...
INSERT … ON DUPLICATE KEY (do nothing)
... uses resources for the second action.
Use INSERT IGNORE ...,
Negative : MySQL will not show any errors if something goes wrong, so you cannot handle the errors. Use it only if you don’t care about the query.
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How to find the lowest common ancestor of two nodes in any binary tree?
...ible. For both nodes in question construct a list containing the path from root to the node by starting at the node, and front inserting the parent.
So for 8 in your example, you get (showing steps): {4}, {2, 4}, {1, 2, 4}
Do the same for your other node in question, resulting in (steps not shown...