dict1 = {'a': 1, 'b': 2}
dict2 = {'c': 3, 'd': 4}
dict3 = {**dict1, **dict2} # python3.5+ 写法
dict3 = dict(dict1, **dict2) # python3.5- 写法
print(dict3)

xs = {'a': 4, 'b': 3, 'c': 2, 'd': 1}
for k, v in sorted(xs.items(), key=lambda x: x[1]):
    print(k, v)

import operator
xs = {'a': 4, 'b': 3, 'c': 2, 'd': 1}
for k, v in sorted(xs.items(), key=operator.itemgetter(1)):
    print(k, v)

import pymongo

myclient = pymongo.MongoClient(host="localhost", port=27017)
mydb = myclient.database_name
collection_obj = mydb.collection_name
# upsert 是否插入新数据，如果不存在则插入，存在则更新 
collection_obj.update_one({"id": "1"}, {"$set": {"id": "1", "age": 18}}, upsert=True)

2018-11-07T16:50:44.165+0800  W FTDC     [ftdc] Uncaught exception in 'FileStreamFailed: Failed to write to interim file buffer for full-time diagnostic data capture: /var/lib/mongo/diagnostic.data/metrics.interim.temp' in full-time diagnostic data capture subsystem. Shutting down the full-time diagnostic data capture subsystem.
2018-11-07T16:51:30.913+0800 E STORAGE  [WTCheckpointThread] WiredTiger error (28)：handle-write: pwrite: failed to write 4096 bytes at offset 1486848: No space left on device
2018-11-07T16:51:30.914+0800 E STORAGE  [WTCheckpointThread] WiredTiger error (28): fatal checkpoint failure: No space left on device
2018-11-07T16:51:30.914+0800 E STORAGE  [WTCheckpointThread] WiredTiger error (-31804)  WT_SESSION.checkpoint: the process must exit and restart: WT

# downloads postgresql-10.3.tar.gz
wget https://ftp.postgresql.org/pub/source/v10.3/postgresql-10.3.tar.gz
wget https://ftp.postgresql.org/pub/source/v10.3/postgresql-10.3.tar.gz.md5
wget https://ftp.postgresql.org/pub/source/v10.3/postgresql-10.3.tar.gz.sha256

# MD5 check 检查数据是否被篡改
cat postgresql-10.3.tar.gz.md5
md5sum  postgresql-10.3.tar.gz

# extract
tar -xvf postgresql-10.3.tar.gz

cd postgresql-10.3/

# 安装文档介绍的很详细
cat INSTALL

./configure

# 提示缺少readline library， 尝试安装libreadline5-dev 提示已被libreadline-gplv2-dev 替代， 安装之
checking for library containing readline... no
configure: error: readline library not found

sudo apt install libreadline5-dev

However the following packages replace it:
  libreadline-gplv2-dev:i386 libreadline-gplv2-dev

sudo apt install libreadline-gplv2-dev


checking for inflate in -lz... no
configure: error: zlib library not found
# 又提示缺失zlib library， 安装之
sudo apt install zlib1g-dev 

# 后边编译安装就顺利了：）
make
sudo make install
sudo adduser postgres
sudo mkdir /usr/local/pgsql/data
sudo chown postgres /usr/local/pgsql/data
su - postgres
# 初始化数据库
/usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
or
initdb -D  /usr/local/pgsql/data

# start the database server
/usr/local/pgsql/bin/postgres -D /usr/local/pgsql/data >logfile 2>&1 &
or
pg_ctl -D /usr/local/pgsql/data -l logfile start
# 测试成功
/usr/local/pgsql/bin/createdb test
/usr/local/pgsql/bin/psql test

# set postgresql env to .bashrc
export PGHOME=/usr/local/pgsql
export PGDATA=/usr/local/pgsql/data
export PATH=$PGHOME/bin:$PATH:$HOME/bin

# CREATEDB是权限，还有其它权限，比如SUPERUSER、CREATEUSER等。一般情况下CREATEDB是最安全的做法。因为这个test用户的权限被限制在很小范围。
CREATE USER username CREATEDB; 
# 修改用户密码
ALTER USER username PASSWORD 'password';

# edit postgresql.conf '*' replace 'localhost'
vim /usr/local/pgsql/data/postgresql.conf
#listen_addresses = 'localhost'
listen_addresses = '*'

# edit pg_hba.conf
vim /usr/local/pgsql/data/pg_hba.conf

# IPv4 local connections: add username authentication
host    all             all             127.0.0.1/32            trust
host    all             username        0.0.0.0/0               md5

# 重启使之生效
su - postgres
pg_ctl restart

OM 
vande gurunam caranaravinde 
sandarsita svatma sukhava bodhe 
nih sreyase jangalikayamane 
samsara halahala mohasantyai
abahu purusakaram 
sankhacakrasi dharinam 
sahasra sirasam svetam 
pranamami patanjalim 
OM

OM 
I bow to the two lotus feet of the Gurus which awaken insight into the happiness of pure Being, 
which are the refuge, the jungle physician, which eliminate the delusion caused by the 
poisonous herb of Samara (conditioned existence)
I prostrate before the 
sage Patanjali who has thousands of radiant, white heads (as the divine 
serpent, Ananta) and who has, as far as his arms, assumed the form of a man holding a conch 
shell (divine sound), a wheel (discus of light or infinite time) and a sword (discrimination
) 
OM

OM
Vande = bow 
Gurunam = to the plurality of gurus 
Caranaravinde = two lotus feet
sandarsita = to bring to sight 
Svatma = pure Being 
Sukhava = happiness 
Bodhe = awakened
nishreyase = refuge 
jangalikayamane = 
jungle hut (meaning shaman, jungle physician)
samsara = conditioned existence 
halahala = poison 
moha = delusion 
santyai = peace
abahu = down to the shoulders 
purusakaram = assumes the form of a man
sankha = conch shell 
cakra = a wheel (discus of light
or infinite time) 
asi = sword (of discrimination) 
dharinam = holding
sahasra = thousands 
sirasam = heads 
svetam = radiant, white
pranamami = prostrate 
patanjalim = the sage Patanjali