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终极SQL执行计划绑定
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MOS：215187.1
[oracle@oraadg1 admin]$ sqlplus dengw/dengw@pdb1
SQL*Plus: Release 12.2.0.1.0 Production on Mon Dec 25 14:55:12 2017
Copyright (c) 1982, 2016, Oracle. All rights reserved.
Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production
SQL> create table T1 as select * from dba_objects where object_id is not null;
Table created.
SQL> alter table T1 modify object_id not null;
Table altered.
SQL> create index idx_T1_obj_id on T1(object_id);
Index created.
SQL> analyze table T1 compute statistics;
Table analyzed.
SQL> select count(*) from T1;
COUNT(*)
----------
22216
SQL> select * from table(dbms_xplan.display_cursor(null,0));
PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------
-
SQL_ID 8w42c0qnug0w7, child number 0
-------------------------------------
select count(*) from T1
Plan hash value: 1836624960
-------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | 15 (100)| |
| 1 | SORT AGGREGATE | | 1 | | |
PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------
-
| 2 | INDEX FAST FULL SCAN| IDX_T1_OBJ_ID | 22216 | 15 (0)| 00:00:01 |
-------------------------------------------------------------------------------
14 rows selected.
SQL> select /*+ full(T1) */ count(*)from T1;
COUNT(*)
----------
22216
SQL> select * from table(dbms_xplan.display_cursor(null,0));
PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------
-
SQL_ID fp5ksbhww4594, child number 0
-------------------------------------
select /*+ full(T1) */ count(*)from T1
Plan hash value: 249608387
-------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | 112 (100)| |
| 1 | SORT AGGREGATE | | 1 | | |
PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------
-
| 2 | TABLE ACCESS FULL| T1 | 22216 | 112 (0)| 00:00:01 |
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