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搭建高可用mongodb集群（四）—— 分片 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...了，安装软件！
1、准备机器，IP分别设置为： 192.168.0.136、192.168.0.137、192.168.0.138。
2、分别在每台机器上建立mongodb分片对应测试文件夹。
#存放mongodb数据文件
mkdir -p /data/mongodbtest
#进入mongodb文件夹
cd /data/mongodbtest
3...
Find integer index of rows with NaN in pandas dataframe
...MultiIndex that you can use to index back into df, e.g.:
df['a'].ix[index[0]]
>>> 1.452354
For the integer index:
df_index = df.index.values.tolist()
[df_index.index(i) for i in index]
>>> [3, 6]
share...
Black transparent overlay on image hover with only CSS?
... the img element itself, see.
.image {
position: relative;
width: 400px;
height: 400px;
}
Give the child img element a width of 100% of the parent and add vertical-align:top to fix the default baseline alignment issues.
.image img {
width: 100%;
vertical-align: top;
}
As for th...
Is this a “good enough” random algorithm; why isn't it used if it's faster?
... QuickRandom qr = new QuickRandom();
int[] frequencies = new int[10];
for (int i = 0; i < 100000; i++) {
frequencies[(int) (qr.random() * 10)]++;
}
printDistribution("QR", frequencies);
frequencies = new int[10];
for (int i = 0; i <...
How to configure PostgreSQL to accept all incoming connections
...
Just use 0.0.0.0/0.
host all all 0.0.0.0/0 md5
Make sure the listen_addresses in postgresql.conf (or ALTER SYSTEM SET) allows incoming connections on all available IP interfaces.
listen_addres...
Create an empty list in python with certain size
... want to create an empty list (or whatever is the best way) that can hold 10 elements.
15 Answers
...
Validate that a string is a positive integer
...
302
Two answers for you:
Based on parsing
Regular expression
Note that in both cases, I've inte...
std::vector performance regression when enabling C++11
...ck(Item());)
$ g++ -std=c++11 -O3 -flto regr.cpp && perf stat -r 10 ./a.out
Performance counter stats for './a.out' (10 runs):
35.426793 task-clock # 0.986 CPUs utilized ( +- 1.75% )
4 context-switches # 0.116 K/sec ...
what does -webkit-transform: translate3d(0,0,0); exactly do? Apply to body?
what does -webkit-transform: translate3d(0,0,0); exactly do?
Does it have any performance issues? Should I just apply it to the body or individual elements? It seems to improve scroll events drastically.
...
Truncate number to two decimal places without rounding
...eform.rounded
var with2Decimals = num.toString().match(/^-?\d+(?:\.\d{0,2})?/)[0]
rounded.value = with2Decimals
}
<form onsubmit="return calc(this)">
Original number: <input name="original" type="text" onkeyup="calc(form)" onchange="calc(form)" />
<br />"Rounded" numb...