drop table t purge;
create table t as select * from dba_objects;
create index idx_object_id on t(object_id,object_type);
UPDATE t SET OBJECT_ID=20 WHERE ROWNUM<=26000;
UPDATE t SET OBJECT_ID=21 WHERE OBJECT_ID<>20;
COMMIT;
set linesize 266
set pagesize 1
alter session set statistics_level=all ;
select /*+index(t,idx_object_id)*/ * from t where object_TYPE='TABLE' AND OBJECT_ID >= 20 AND OBJECT_ID<= 21;
select * from table(dbms_xplan.display_cursor(null,null,'allstats last'));
-------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers |
-------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 2925 |00:00:00.03 | 1103 |
| 1 | TABLE ACCESS BY INDEX ROWID| T | 1 | 2126 | 2925 |00:00:00.03 | 1103 |
|* 2 | INDEX RANGE SCAN | IDX_OBJECT_ID | 1 | 320 | 2925 |00:00:00.02 | 730 |
-------------------------------------------------------------------------------------------------------
select /*+index(t,idx_object_id)*/ * from t t where object_TYPE='TABLE' AND OBJECT_ID IN (20,21);
select * from table(dbms_xplan.display_cursor(null,null,'allstats last'));
---------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers |
---------------------------------------------------------------------------------------------------------
| 1 | INLIST ITERATOR | | 1 | | 2920 |00:00:00.01 | 563 |
| 2 | TABLE ACCESS BY INDEX ROWID| t | 2 | 2592 | 2920 |00:00:00.01 | 563 |
|* 3 | INDEX RANGE SCAN | IDX1_OBJECT_ID | 2 | 1 | 2920 |00:00:00.01 | 214 |
--------------------------------------------------------------------------------------------------------
三十五、in写法差异
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