這篇文章主要介紹了Oracle外鍵不加索引引起死鎖的情況及解決,需要的朋友可以參考下

--創(chuàng)建一個(gè)表，此表作為子表

create table fk_t as select * from user_objects;

delete from fk_t where object_id is null;

commit;

--創(chuàng)建一個(gè)表，此表作為父表

create table pk_t as select * from user_objects;

delete from pk_t where object_id is null;

commit;

--創(chuàng)建父表的主鍵

alter table PK_t add constraint pk_pktable primary key (OBJECT_ID);

--創(chuàng)建子表的外鍵

alter table FK_t add constraint fk_fktable foreign key (OBJECT_ID) references pk_t (OBJECT_ID);

--session1:執(zhí)行一個(gè)刪除操作，這時(shí)候在子表和父表上都加了一個(gè)Row-S(SX)鎖

delete from fk_t where object_id=100;

delete from pk_t where object_id=100;

--session2:執(zhí)行另一個(gè)刪除操作，發(fā)現(xiàn)這時(shí)候第二個(gè)刪除語(yǔ)句等待

delete from fk_t where object_id=200;

delete from pk_t where object_id=200;

--回到session1:死鎖馬上發(fā)生

delete from pk_t where object_id=100;

session2中報(bào)錯(cuò)：

SQL> delete from pk_table where object_id=200;

delete from pk_table where object_id=200

*

第 1 行出現(xiàn)錯(cuò)誤:

ORA-00060: 等待資源時(shí)檢測(cè)到死鎖

當(dāng)對(duì)子表的外鍵列添加索引后，死鎖被消除，因?yàn)檫@時(shí)刪除父表記錄不需要對(duì)子表加表級(jí)鎖。

--為外鍵建立索引

create index ind_pk_object_id on fk_t(object_id) nologging;

--重復(fù)上面的操作session1

delete from fk_t where object_id=100;

delete from pk_t where object_id=100;

--session2

delete from fk_t where object_id=200;

delete from pk_t where object_id=200;

--回到session1不會(huì)發(fā)生死鎖

delete from pk_t where object_id=100;

經(jīng)過(guò)驗(yàn)證，如果外鍵不加索引的確會(huì)出現(xiàn)死鎖。因此，外鍵務(wù)必添加索引。

總結(jié)

以上是生活随笔為你收集整理的测试的时候数据库外键导致死锁_Oracle外键不加索引会引起死锁问题的全部?jī)?nèi)容，希望文章能夠幫你解決所遇到的問(wèn)題。

如果覺(jué)得生活随笔網(wǎng)站內(nèi)容還不錯(cuò)，歡迎將生活随笔推薦給好友。