Scene 1 delete from T;
1 T table parentid and id is a foreign key relationship, resulting in gaps in the process of executing delete from t ENQ:TM CONTENTION
2 There is a delete trigger in the T table, which leads to the need to update the data in the T1 table during the delete process, resulting in a db file sqeuenial read (corresponding P1, P2 are the file id and block id corresponding to the T1 table object)
Scenario 2 insert produces a large number of db file sqeuenial read
1 Maintain the index
2 Trigger exists