導讀:1建站知識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如何seo優化推廣網站高端網站建設。

--創建一個表，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; --創建一個表，此表作為父表 create table pk_t as select *from user_objects; d網站建設制作elete from pk_t where object_id is null; commit; --創建父表的主鍵 alter table PK_t add constraintpk_pktable primary key (OBJECT_ID); --創建子表的外鍵 alter table FK_t addconstraint fk_fktable foreign key (OBJECT_ID) references pk_t (OBJECT_ID); --session1:執行一個刪除操作，這時候在子表和父表上都加了一個Row-S(SX)鎖 delete from fk_t whereobject_id=100; delete from pk_t where object_id=100; --session2:執行另一個刪除操作，網站優化seo培訓發現這時候第二個刪除語句等待 delete from fk_t whereobject_id=200; delete from pk_t whereobject_id=200; --回到session1:死鎖馬上發生 delete from pk_t whereobject_id=100; session2中報錯： SQL> delete from pk_table where object_id=200; delete from pk_table where object_id=200 * 第 1seo網站關鍵詞優化 行出現錯誤: ORA-00060: 等待資源時檢測到死鎖 當對子表的外鍵列添加索引后，死鎖被消除，因為這時刪除父表記錄不需要對子表加表級鎖。 --為外鍵建立索引 create index ind_pk_object_id on fk_t(object_id) nologging; --重復上面的操作session1 delete from fk_t whereobject_id=100; delete from pk_t whereobject_id=100; --session2 delete from fk_t whereobject_id=200; delete from pk_t whereobject_id=200; --回到session1不會發生死鎖 delete from pk_t whereobject_id=100;相關如何seo優化推廣網站高端網站建設。

關鍵詞標簽: 示例 死鎖