在oracle中模拟index contention

conn dayu/dayu

create table test as select * from dba_objects;

alter table test add constraint test_p primary key (object_id);

create index test_name on test(object_name);

**************
常规写法
**************

DECLARE
  i number := 0;
BEGIN
  for i in 90000 .. 200000 loop
    if mod(i,2)=0 then    
    insert into test
      (object_id,object_name, owner)
    values
      (i+2,'dayu','dayu');      
  commit;
  end if;
  end loop;
END;


DECLARE
  i number := 0;
BEGIN
  for i in 90000 .. 200000 loop
    if mod(i,2)=1 then    
    insert into test
      (object_id,object_name, owner)
    values
      (i+2,'dayu', 'dayu');      
  commit;
  end if;
  end loop;
END;


****************
创建trigger
****************
create sequence testseq
increment by 1 
start with 900000 
maxvalue 999999999 
cycle
cache 200;


create or replace trigger test_trigger
before insert on test 
for each row           
declare               
    tempkey test.object_id%type; 
begin
    select testseq.NEXTVAL into tempkey from dual; 
    if :new.object_id is null then                  
         :new.object_id := tempkey+1; 
    end if;
end;

DECLARE
  i number := 0;
BEGIN
  for i in 90000 .. 200000 loop
    if mod(i,2)=0 then    
    insert into test
      (object_name, owner)
    values
      ('dayu','dayu');      
  commit;
  end if;
  end loop;
END;


DECLARE
  i number := 0;
BEGIN
  for i in 90000 .. 200000 loop
    if mod(i,2)=1 then    
    insert into test
      (object_name, owner)
    values
      ('dayu', 'dayu');      
  commit;
  end if;
  end loop;
END;


****************
直接调用sequence
****************


DECLARE
  i number := 0;
BEGIN
  for i in 90000 .. 200000 loop
    if mod(i,2)=0 then    
    insert into test
      (object_id,object_name, owner)
    values
      (testseq.NEXTVAL,'dayu','dayu');      
  commit;
  end if;
  end loop;
END;


DECLARE
  i number := 0;
BEGIN
  for i in 90000 .. 200000 loop
    if mod(i,2)=1 then    
    insert into test
      (object_id,object_name, owner)
    values
      (testseq.NEXTVAL,'dayu', 'dayu');      
  commit;
  end if;
  end loop;
END;

 

 

转载于:https://www.cnblogs.com/dayu-liu/p/9394155.html