如何自动关闭PostgreSQL中的空闲连接？

You could use a cron job to look at when the connection was last active (see pg_stat_activity) and use pg_terminate_backend to kill old ones. Easily expressed in a simple query. I’m not sure if pg_terminate_backend was available in the pretty-ancient 8.3,though.

所选解决方案如下：

>首先，我们升级到Postgresql 9.2。
>然后，我们安排线程每秒运行一次。
>当线程运行时，它会查找任何旧的非活动连接。

• A connection is considered inactive if its state is either idle,idle in transaction,idle in transaction (aborted) or disabled.
• A connection is considered old if its last state has changed for more than 5 minutes.

>还有一些额外的线程和上面的一样。但是，这些线程与不同的用户连接到数据库。
>我们至少为连接到我们的数据库的任何应用程序打开一个连接。 (rank()函数)

这是线程运行的SQL查询：

WITH inactive_connections AS (
    SELECT
        pid,rank() over (partition by client_addr order by backend_start ASC) as rank
    FROM 
        pg_stat_activity
    WHERE
        -- Exclude the thread owned connection (ie no auto-kill)
        pid <> pg_backend_pid( )
    AND
        -- Exclude known applications connections
        application_name !~ '(?:psql)|(?:pgAdmin.+)'
    AND
        -- Include connections to the same database the thread is connected to
        datname = current_database() 
    AND
        -- Include connections using the same thread username connection
        usename = current_user 
    AND
        -- Include inactive connections only
        state in ('idle','idle in transaction','idle in transaction (aborted)','disabled') 
    AND
        -- Include old connections (found with the state_change field)
        current_timestamp - state_change > interval '5 minutes' 
)
SELECT
    pg_terminate_backend(pid)
FROM
    inactive_connections 
WHERE
    rank > 1 -- Leave one connection for each application connected to the database