如何自动关闭PostgreSQL中的空闲连接？ [英] How to close idle connections in PostgreSQL automatically?

问题描述

一些客户端连接到我们的postgresql数据库，但是打开连接。
是否可以告诉Postgresql在一定时间不活动后关闭这些连接？

Some clients connect to our postgresql database but leave the connections opened. Is it possible to tell Postgresql to close those connection after a certain amount of inactivity ?

TL; DR

TL;DR

如果您使用的是Postgresql版本> = 9.2

使用我想出的解决方案

如果您不想写任何代码

然后使用 arqnid的解决方案

IF you don't want to write any code
THEN use arqnid's solution

推荐答案

对于那些感兴趣的人，这里是从 Craig Ringer 的意见：

For those who are interested, here is the solution I came up with from Craig Ringer's comment:

您可以使用cron作业来查看连接上次活动的时间（请参见pg_stat_activity），并使用pg_terminate_backend删除旧的连接。在一个简单的查询中轻松表达。我不知道pg_terminate_backend是否在非常古老的8.3中可用。

像这样：

• 首先，我们升级到Postgresql 9.2。


• 然后，


• 当线程运行时，它会查找任何旧的非活动连接。
  
  

• First, we upgrade to Postgresql 9.2.
• Then, we schedule a thread to run every second.
• When the thread runs, it looks for any old inactive connections.

• 如果某个连接的状态 code>空闲，空闲在事务，空闲在事务中（中止）或 disabled 。


• 如果连接的最后状态更改时间超过5分钟，则认为该连接为旧 。

• 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.

有其他线程与上述相同。但是，这些线程使用不同的用户连接到数据库。

我们为连接到我们数据库的任何应用程序至少保留一个连接。 （ rank（） function）

There are additional threads that do the same as above. However, those threads connect to the database with different user.

We leave at least one connection open for any application connected to our database. (rank() function)

线程：

WITH inactive_connections_list 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_list 
WHERE
    rank > 1 -- Leave one connection for each application connected to the database

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