在postgresql中结束掉正在执行的SQL语句操作

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。

我想要获取技术服务或软件
服务范围：MySQL、ORACLE、SQLSERVER、MongoDB、PostgreSQL 、程序问题
服务方式：远程服务、电话支持、现场服务，沟通指定方式服务
技术标签：数据恢复、安装配置、数据迁移、集群容灾、异常处理、其它问题

本站部分文章参考或来源于网络，如有侵权请联系站长。
数据库远程运维 在postgresql中结束掉正在执行的SQL语句操作