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在postgresql中結(jié)束掉正在執(zhí)行的SQL語句操作

更新時間：2020年12月30日 16:03:14 作者：hy.ding

這篇文章主要介紹了在postgresql中結(jié)束掉正在執(zhí)行的SQL語句操作，具有很好的參考價值，希望對大家有所幫助。一起跟隨小編過來看看吧

結(jié)束進程兩種方式：

SELECT pg_cancel_backend(PID)

取消后臺操作，回滾未提交事物 (select);

SELECT pg_terminate_backend(PID)

中斷session，回滾未提交事物(select、update、delete、drop);

SELECT * FROM pg_stat_activity;

根據(jù)datid=10841

SELECT pg_terminate_backend (10841);

補充：PostgreSQL無法在PL / pgSQL中開始/結(jié)束事務(wù)

我正在尋求澄清如何確保plpgsql函數(shù)中的原子事務(wù),以及為數(shù)據(jù)庫進行此特定更改設(shè)置了隔離級別.

在下面顯示的plpgsql函數(shù)中,我想確保BOTH的刪除和插入成功.當我嘗試將它們包裝在一個事務(wù)中時,我收到一個錯誤：

錯誤：無法在PL / pgSQL中開始/結(jié)束事務(wù).

如果另一個用戶在此功能已刪除自定義記錄之后,但在此函數(shù)有機會插入自定義記錄之前,為情況(RAIN,NIGHT,45MPH)添加了默認行為,下面的函數(shù)執(zhí)行過程中會發(fā)生什么？是否有一個隱式事務(wù)包裝插入和刪除,以便如果另一個用戶已經(jīng)更改了此函數(shù)引用的任何一個行,兩者都將回滾？我可以設(shè)置此功能的隔離級別嗎？

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

一個plpgsql函數(shù)在事務(wù)中自動運行.這一切都成功了,一切都失敗了.

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,你可以捕獲理論上可能發(fā)生的異常(但是不大可能).

Details on trapping errors in the manual.

您的功能審查和簡化：

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

以上為個人經(jīng)驗，希望能給大家一個參考，也希望大家多多支持腳本之家。如有錯誤或未考慮完全的地方，望不吝賜教。

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