# 網絡檢查
ping -c2 baidu.com
#關閉防火墻，selinux
systemctl stop firewalld  sudo systemctl disable firewalld
sed -ri s/SELINUX=enforcing/SELINUX=disabled/g /etc/selinux/config
setenforce 0
### 配置阿里云yum源
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
#echo "isntalling tools"
yum -y install vim net-tools wget ntpdate
yum -y groupinstall "Development Tools"
# 時間同步
echo "*/10 * * * * /usr/sbin/ntpdate ntp.aliyun.com > /dev/null 2>1" >>/etc/crontab
# 加快ssh連接
sed -ri s/"#UseDNS yes"/"UseDNS no"/g /etc/ssh/sshd_config
systemctl restart sshd
## 環境準備，根據自身需要，減少或者增加
yum install -y wget gcc gcc-c++ epel-release llvm5.0 llvm5.0-devel clang libicu-devel perl-ExtUtils-Embed readline readline-devel zlib zlib-devel openssl openssl-devel pam-devel libxml2-devel libxslt-devel openldap-devel systemd-devel tcl-devel python-devel
## 下載、解壓，安裝
cd /usr/local/src
wget https://ftp.postgresql.org/pub/source/v12.0/postgresql-12.0.tar.gz
tar -xvzf postgresql-12.tar.gz
cd postgresql-12
./configure --prefix=/usr/local/pgsql/12 --enable-nls --with-python --with-tcl --with-gssapi --with-icu --with-openssl --with-pam --with-ldap --with-systemd --with-libxml --with-libxslt
make  make install
## 創建目錄和用戶,以及配置環境變量
groupadd postgres
useradd -g postgres postgres
## 密碼設置在引號內輸入自己的密碼
echo "postgres" | passwd --stdin postgres
mkdir -p /data/pgdata/{data,archivedir}
chown -R postgres:postgres /usr/local/pgsql -R
chown postgres:postgres /data/pgdata -R
echo "export PATH=/usr/local/pgsql/12/bin:$PATH" >/etc/profile.d/pgsql.sh
source /etc/profile.d/pgsql.sh

su - postgres
##初始化
initdb -D /data/pgdata/data -U postgres --locale=en_US.UTF8 -E UTF8
cp /data/pgdata/data/{pg_hba.conf,pg_hba.conf.bak}
## 允許repl用戶進行流復制
cat -eof >>/data/pgdata/data/pg_hba.conf
host all    all    0.0.0.0/0    md5
host replication  repl   192.168.0.0/22   trust
eof
cp /data/pgdata/data/{postgresql.conf,postgresql.conf.bak}
##配置postgresql.conf
cat -eof >/data/pgdata/data/postgresql.conf
listen_addresses = '*'      
port = 5432
max_connections = 100
superuser_reserved_connections = 10
full_page_writes = on
wal_log_hints = off
max_wal_senders = 50
hot_standby = on
log_destination = 'csvlog'
logging_collector = on
log_directory = 'log'
log_filename = 'postgresql-%Y-%m-%d_%H%M%S'
log_rotation_age = 1d
log_rotation_size = 10MB
log_statement = 'mod'
log_timezone = 'PRC'
timezone = 'PRC'
unix_socket_directories = '/tmp'
shared_buffers = 512MB
temp_buffers = 16MB
work_mem = 32MB
effective_cache_size = 2GB
maintenance_work_mem = 128MB
#max_stack_depth = 2MB
dynamic_shared_memory_type = posix
## PITR
full_page_writes = on
wal_buffers = 16MB
wal_writer_delay = 200ms
commit_delay = 0
commit_siblings = 5
wal_level = replica
archive_mode = on
archive_command = 'test ! -f /data/pgdata/archivedir/%f  cp %p /data/pgdata/archivedir/%f'
archive_timeout = 60s
eof
## 啟動數據庫
pg_ctl -D /data/pgdata/data -l /data/pgdata/data/serverlog start
## 創建用戶進行流復制連接
psql -U postgres -c "ALTER USER postgres WITH PASSWORD 'postgres';"
psql -U postgres -c "CREATE USER repl WITH PASSWORD 'postgres' REPLICATION;"

## 備份復制，備庫配置，
pg_basebackup -h 192.168.3.62 -p 5432 -U repl -w -Fp -Xs -Pv -R -D /data/pgdata/data
根據主庫的postgresql.conf 配置文件 修改參數配置:
1, listen_addresses = '* '
2, wal_level = hot_standby
3, max_connections = xxx, # 一般比主庫大一些.
4,hot_standby = on
5, max_standby_streaming_delay = 30s
6. wal_receiver_status_interval = 10s
7, hot_standby_feedback = on # 如果有錯誤的數據復制,是否向 主進行范例.
### 在postgre.auto.conf 添加 application_name =slave1,配置如下
primary_conninfo = 'application_name=slave1 user=repl passfile=''/home/postgres/.pgpass'' host=192.168.3.62 port=5432 sslmode=prefer sslcompression=0 gssencmode=prefer krbsrvname=postgres target_session_attrs=any'
## 啟動備庫
pg_ctl -D /data/pgdata/data start

##狀態檢查
### 回到主庫查看狀態
$ psql -c "select client_addr,usename,backend_start,application_name,sync_state,sync_priority FROM pg_stat_replication;"
 client_addr | usename |   backend_start   | application_name | sync_state | sync_priority 
--------------+---------+-------------------------------+------------------+------------+---------------
 192.168.3.61 | repl | 2019-10-16 15:34:45.130732+08 | slave1   | async  |    0
(1 row)
$ psql -c "select client_addr, sync_state from pg_stat_replication;"
 client_addr | sync_state 
--------------+------------
 192.168.3.61 | async
(1 row)
##備庫只讀, 所以任何操作, 都會告警失敗:
postgres=# drop database pgtest;
ERROR: cannot execute DROP DATABASE in a read-only transaction
## 查看主備的狀態
#主
ps -ef |grep sender
postgres 92996 51692 0 15:34 ?  00:00:00 postgres: walsender repl 192.168.3.61(53958) streaming 0/8000060
postgres 101845 20470 0 15:45 pts/2 00:00:00 grep --color=auto sender
#備
ps -ef |grep recover
postgres 98311 98309 0 15:34 ?  00:00:00 postgres: startup recovering 000000010000000000000008
postgres 108029 21054 0 15:46 pts/2 00:00:00 grep --color=auto recover
#通過此命令判斷主備
pg_controldata -D /data/pgdata/data/ |grep state
in archive recovery ## 表示從庫
in production  ## 表示主庫

WITH AllUsers AS (SELECT * FROM Users)
SELECT * FROM AllUsers WHERE Id = 100;

WITH UserRecord AS (SELECT * FROM Users WHERE Id = 100)
SELECT * FROM UserRecord;

WITH AllUsers AS NOT MATERIALIZED (SELECT * FROM Users)
SELECT * FROM AllUsers WHERE Id = 100;

CREATE TABLE Employee (
 ...,
 dob timestamp,
 age integer GENERATED ALWAYS AS (date_part('year', CURRENT_TIME - dob)) STORED
);

CREATE OR REPLACE FUNCTION calc_age() RETURNS TRIGGER AS $body$
BEGIN
 NEW.age := date_part('year', CURRENT_TIME - NEW.dob::timestamp);
 RETURN NEW;
END; 
$body$ LANGUAGE plpgsql;

-- SQL Server Syntax
CREATE TABLE Employee (
 ...,
 dob datetime,
 age AS DATEDIFF(year,dob,GETDATE()) PERSISTED
);

CREATE TABLE test (x INTEGER);
INSERT INTO test SELECT generate_series(1, 1000000);
CREATE INDEX i_test ON test (x);
REINDEX INDEXCONCURRENTLY i_test;

CREATE STATISTICS stts3 (mcv) ON state, city FROM zipcodes;
ANALYZE zipcodes;