PostgreSQL备忘

查询链接数

SELECT sum(numbackends) FROM pg_stat_database;

查看死锁状态

select pid,
       usename,
       pg_blocking_pids(pid) as blocked_by,
       query as blocked_query
from pg_stat_activity
where cardinality(pg_blocking_pids(pid)) > 0;

删除死锁进程

SELECT pg_cancel_backend(__pid__);

SELECT pg_terminate_backend(__pid__);

备份数据库

# sql文件
pg_dump dangerousdb > db.sql
# tar文件
pg_dump -U postgres -F c dangerousdb > dangerousdb.tar
# gz文件
pg_dump -U postgres dangerousdb | gzip > dangerousdb.gz

还原数据库

# 已经存在数据库
pg_restore -U postgres -Ft -d dbcooper < dbcooper.tar
# 创建新数据库
pg_restore -U postgres -Ft -C -d dbcooper < dbcooper.tar
#