在postgresql中结束掉正在执行的SQL语句操作

结束进程两种方式:

SELECT pg_cancel_backend(PID)

取消后台操作,回滚未提交事物 (select);

SELECT pg_terminate_backend(PID)

中断session,回滚未提交事物(select、update、delete、drop);

SELECT * FROM pg_stat_activity;

根据datid=10841

SELECT pg_terminate_backend (10841);

补充:PostgreSQL无法在PL / pgSQL中开始/结束事务

我正在寻求澄清如何确保plpgsql函数中的原子事务,以及为数据库进行此特定更改设置了隔离级别.

在下面显示的plpgsql函数中,我想确保BOTH的删除和插入成功.当我尝试将它们包装在一个事务中时,我收到一个错误:

错误:无法在PL / pgSQL中开始/结束事务.

如果另一个用户在此功能已删除自定义记录之后,但在此函数有机会插入自定义记录之前,为情况(RAIN,NIGHT,45MPH)添加了默认行为,下面的函数执行过程中会发生什么?是否有一个隐式事务包装插入和删除,以便如果另一个用户已经更改了此函数引用的任何一个行,两者都将回滚?我可以设置此功能的隔离级别吗?

create function foo(v_weather varchar(10), v_timeofday varchar(10), v_speed varchar(10),

v_behavior varchar(10))

returns setof CUSTOMBEHAVIOR

as $body$

begin

-- run-time error if either of these lines is un-commented

-- start transaction ISOLATION LEVEL READ COMMITTED;

-- or, alternatively, set transaction ISOLATION LEVEL READ COMMITTED;

delete from CUSTOMBEHAVIOR

where weather = 'RAIN' and timeofday = 'NIGHT' and speed= '45MPH' ;

-- if there is no default behavior insert a custom behavior

if not exists

(select id from DEFAULTBEHAVIOR where a = 'RAIN' and b = 'NIGHT' and c= '45MPH') then

insert into CUSTOMBEHAVIOR

(weather, timeofday, speed, behavior)

values

(v_weather, v_timeofday, v_speed, v_behavior);

end if;

return QUERY

select * from CUSTOMBEHAVIOR where ... ;

-- commit;

end

$body$

LANGUAGE plpgsql

一个plpgsql函数在事务中自动运行.这一切都成功了,一切都失败了.

我引用the manual on plpgsql functions:

Functions and trigger procedures are always executed within a transaction established by an outer query — they cannot start or commit that transaction, since there would be no context for them to execute in. However, a block containing an EXCEPTION clause effectively forms a subtransaction that can be rolled back without affecting the outer transaction.

所以,如果你需要,你可以捕获理论上可能发生的异常(但是不大可能).

Details on trapping errors in the manual.

您的功能审查和简化:

CREATE FUNCTION foo(v_weather text

, v_timeofday text

, v_speed text

, v_behavior text)

RETURNS SETOF custombehavior AS

$body$

BEGIN

DELETE FROM custombehavior

WHERE weather = 'RAIN'

AND timeofday = 'NIGHT'

AND speed = '45MPH';

INSERT INTO custombehavior (weather, timeofday, speed, behavior)

SELECT v_weather, v_timeofday, v_speed, v_behavior

WHERE NOT EXISTS (

SELECT 1 FROM defaultbehavior

WHERE a = 'RAIN'

AND b = 'NIGHT'

AND c = '45MPH'

);

RETURN QUERY

SELECT * FROM custombehavior WHERE ... ;

END

$body$LANGUAGE plpgsql

以上为个人经验,希望能给大家一个参考,也希望大家多多支持。如有错误或未考虑完全的地方,望不吝赐教。

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