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记一次MongoDB性能问题 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
... mongod like this to avoid performance problems: numactl –interleave=all mongod [other options]
当时我并不太清楚NUMA是什么东西，所以没有处理，只是把问题反馈给了运维人员，后来知道运维人员也没有理会这茬儿，所以问题的序幕就这样拉开...
Django - How to rename a model field using South?
I would like to change a name of specific fields in a model:
6 Answers
6
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How to make MySQL handle UTF-8 properly
... My understanding is that utf8 within MySQL only refers to a small subset of full Unicode. You should use utf8mb4 instead to force full support. See mathiasbynens.be/notes/mysql-utf8mb4 "For a long time, I was using MySQL’s utf8 charset for databases, tables, and columns, assuming i...
A field initializer cannot reference the nonstatic field, method, or property
... So your explanation is wrong. The order is fixed. The reason why it is disallowed is that the designers of C# wanted it that way.
– Jeppe Stig Nielsen
Apr 18 '16 at 20:16
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GET URL parameter in PHP
...perglobal: a built-in variable that's populated by PHP and is available in all scopes (you can use it from inside a function without the global keyword).
Since the variable might not exist, you could (and should) ensure your code does not trigger notices with:
<?php
if (isset($_GET['link'])) {
...
Scala actors: receive vs react
...ead until it receives something. Once it receives something, a thread gets allocated to it, and it is initialized in it.
Now, the initialization part is important. A receiving thread is expected to return something, a reacting thread is not. So the previous stack state at the end of the last react ...
How to terminate a Python script
...ed by raising the
SystemExit exception, so cleanup actions specified by finally clauses
of try statements are honored, and it is possible to intercept the
exit attempt at an outer level.
The optional argument arg can be an integer giving the exit status
(defaulting to zero), or another type of obj...
Typescript: difference between String and string
...e of String. You probably never need to use it, string literals are universally accepted as being the correct way to initialise a string. In JavaScript, it is also considered better to use object literals and array literals too:
var arr = []; // not var arr = new Array();
var obj = {}; // not var o...
Is python's sorted() function guaranteed to be stable?
...s what is expected in this case? Python is going to compare tuples through all elements by default, not just the first "primary" one. If you only want to sort on the first element, you can pass the key parameter explicitly.
– Matias Grioni
Nov 30 '17 at 3:52
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Assign pandas dataframe column dtypes
... of multiple columns in pd.Dataframe (I have a file that I've had to manually parse into a list of lists, as the file was not amenable for pd.read_csv )
...