1、根据中文拼音排序
select * from t order by convert_to(name,'GBK') DESC;
2、根据IP来排序，postgresql本身就有IP类型，排序只需要转成IP类型排序即可。
SELECT * FROM t order by CAST(ip as inet) desc;
3、数据库的备份与恢复
#备份
/usr/pgsql-9.5/bin/pg_dump -h 192.168.90.215 -U postgres ivycloud_clouddoc >/opt/bak/ivycloud_clouddoc.bak
#恢复
/usr/pgsql-9.4/bin/psql -h 192.168.90.205 -U postgres ivycloud_clouddoc < /home/ivycloud_clouddoc.bak
4、删除存在回话的数据库
SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE pid <> pg_backend_pid();
5、创建数据库时报错，错误如下：
ERROR: source database "template1" is being accessed by other users
DETAIL: There is 1 other session using the database.
解决方式（暴力解决）：
查询出连接该数据库的进程，并将其杀死。
select pg_terminate_backend(pid) from pg_stat_activity where DATNAME = 'template1';
6、shell脚本执行创建数据库失败，命令：sudo -u postgres /opt/pgsql/bin/createdb -O postgres <database_name>
解决方式：
sed -i -e 's/Defaults requiretty.*/ #Defaults requiretty/g' /etc/sudoers
