Oracle ---- 固定执行计划之SPM
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今天终于说到了SPM，一个ORACLE官方推荐使用的SQL执行计划固定方法。为什么最常使用的方法最后说呢？因为介绍SPM使用方法的公开资料最多，ORACLE提供的接口也最丰富，用一篇几百字的小文进行说明，总觉得会挂一漏万，以偏概全。
但是考虑再三，作为ORACLE官方大力推荐和持续开发完善的固定执行计划的主要手段，还是不能不说的。
还是像前几个方法一样，我们用一个小的测试例子来说明SPM的使用方法。
1.做成测试用Table。
conn test/test@localhost:1521/pdb
create table tab2(c1 number, c2 number, c3 varchar2(10));
declare
a number;
begin
a := 1;
for i in 1 .. 50 loop
for j in 1 .. 100 loop
insert into tab2 values(a,j,\'a\');
commit;
a := a+1;
end loop;
end loop;
end;
/
create index ind2_2 on tab2(c2);
exec dbms_stats.gather_table_stats(ownname=>\'TEST\',tabname=>\'TAB2\',cascade=>TRUE);
2.执行原始SQL文。
set autot on
set lin 120 pages 999
select count(*) from tab2 where c2=1;
COUNT(*)
----------
50
実行計画
----------------------------------------------------------
Plan hash value: 3563712581
----------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
----------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 3 | 1 (0)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | 3 | | |
|* 2 | INDEX RANGE SCAN| IND2_2 | 50 | 150 | 1 (0)| 00:00:01 |
----------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("C2"=1)
統計
----------------------------------------------------------
4 recursive calls
25 db block gets
4 consistent gets
0 physical reads
832 redo size
573 bytes sent via SQL*Net to client
398 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
3.查看对象SQL文的sql_id和plan_hash_value。
conn sys/*****@localhost:1521/pdb
select sql_id, child_number, plan_hash_value from v$sql where sql_text = \'select count(*) from tab2 where c2=1\';
SQL_ID CHILD_NUMBER PLAN_HASH_VALUE
------------- ------------ ---------------
3uat1k9ssur9p 0 3563712581
4.把对象SQL文的执行计划Load进SPM。
SQL> var cnt number;
SQL> exec :cnt := dbms_spm.load_plans_from_cursor_cache(sql_id => \'&sql_id\', plan_hash_value => \'&plan_hash_value\');
sql_idに値を入力してください: 3uat1k9ssur9p
plan_hash_valueに値を入力してください: 3563712581
PL/SQLプロシージャが正常に完了しました。
SQL> print :cnt
CNT
----------
1
5.查看SQLPLAN的BaseLine。
col sql_handle for a30
col SQL_TEXT for a50
col PLAN_NAME for a30
set lin 120 pages 999
select sql_handle,sql_text, plan_name,fixed from dba_sql_plan_baselines where sql_text like \'select count(*) from tab2 where c2=1\';
SQL_HANDLE SQL_TEXT PLAN_NAME FIX
------------------------------ -------------------------------------------------- ------------------------------ ---
SQL_156e46a7ed64e33d select count(*) from tab2 where c2=1 SQL_PLAN_1avk6nzqq9stx910d0b22 NO
6.固定执行计划。
SQL> exec :cnt := dbms_spm.alter_sql_plan_baseline(sql_handle => \'&sql_handle\', plan_name => \'&plan_name\', attribute_name => \'FIXED\', attribute_value => \'YES\');
sql_handleに値を入力してください: SQL_156e46a7ed64e33d
plan_nameに値を入力してください: SQL_PLAN_1avk6nzqq9stx910d0b22
PL/SQLプロシージャが正常に完了しました。
SQL> select sql_handle,sql_text, plan_name,fixed from dba_sql_plan_baselines where sql_text like \'select count(*) from tab2 where c2=1\';
SQL_HANDLE SQL_TEXT PLAN_NAME FIX
------------------------------ -------------------------------------------------- ------------------------------ ---
SQL_156e46a7ed64e33d select count(*) from tab2 where c2=1 SQL_PLAN_1avk6nzqq9stx910d0b22 YES
7.执行原始SQL文，查看SQLPLAN BASELINE是否被使用。
conn test/test@localhost:1521/pdb
set autot on
set lin 120 pages 999
SQL> select count(*) from tab2 where c2=1;
COUNT(*)
----------
50
実行計画
----------------------------------------------------------
Plan hash value: 3563712581
----------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
----------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 3 | 1 (0)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | 3 | | |
|* 2 | INDEX RANGE SCAN| IND2_2 | 50 | 150 | 1 (0)| 00:00:01 |
----------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("C2"=1)
Note
-----
- SQL plan baseline "SQL_PLAN_1avk6nzqq9stx910d0b22" used for this statement
統計
----------------------------------------------------------
20 recursive calls
41 db block gets
11 consistent gets
0 physical reads
4472 redo size
573 bytes sent via SQL*Net to client
398 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
8.执行加Hint的SQL文。
SQL> select /*+ FULL (TAB2) */ count(*) from tab2 where c2=1;
COUNT(*)
----------
50
実行計画
----------------------------------------------------------
Plan hash value: 2781695375
---------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
---------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 3 | 5 (0)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | 3 | | |
|* 2 | TABLE ACCESS FULL| TAB2 | 50 | 150 | 5 (0)| 00:00:01 |
---------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter("C2"=1)
統計
----------------------------------------------------------
4 recursive calls
25 db block gets
16 consistent gets
0 physical reads
904 redo size
573 bytes sent via SQL*Net to client
417 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
9.查看加Hint的SQL文的sql_id和plan_hash_value。
conn sys/*****@localhost:1521/pdb
select sql_id, child_number, plan_hash_value from v$sql where sql_text like \'select /*+ FULL (TAB2) */ count(*) from tab2 where c2=1\';
SQL_ID CHILD_NUMBER PLAN_HASH_VALUE
------------- ------------ ---------------
556psnns1a273 0 2781695375
10.把加了Hint的SQL文的执行计划加到原始SQL文的BaseLine上。
SQL> var cnt number;
SQL> exec :cnt := dbms_spm.load_plans_from_cursor_cache( sql_id => \'&hinted_SQL_ID\', plan_hash_value => &hinted_plan_hash_value, sql_handle => \'&sql_handle_for_original\');
hinted_sql_idに値を入力してください: 556psnns1a273
hinted_plan_hash_valueに値を入力してください: 2781695375
sql_handle_for_originalに値を入力してください: SQL_156e46a7ed64e33d
PL/SQLプロシージャが正常に完了しました。
SQL> print :cnt
RES
----------
1
11.查看SQLPLAN的BaseLine。
col sql_handle for a30
col SQL_TEXT for a50
col PLAN_NAME for a30
set lin 120 pages 999
select sql_handle,sql_text, plan_name,fixed from dba_sql_plan_baselines where sql_text like \'select count(*) from tab2 where c2=1\';
SQL_HANDLE SQL_TEXT PLAN_NAME FIX
------------------------------ -------------------------------------------------- ------------------------------ ---
SQL_156e46a7ed64e33d select count(*) from tab2 where c2=1 SQL_PLAN_1avk6nzqq9stx910d0b22 YES
SQL_156e46a7ed64e33d select count(*) from tab2 where c2=1 SQL_PLAN_1avk6nzqq9stxfbe5cdec NO
12.删除最初Load的BaseLine。
SQL> exec :cnt :=DBMS_SPM.DROP_SQL_PLAN_BASELINE (\'&original_sql_handle\',\'&original_plan_name\');
original_sql_handleに値を入力してください: SQL_156e46a7ed64e33d
original_plan_nameに値を入力してください: SQL_PLAN_1avk6nzqq9stx910d0b22
PL/SQLプロシージャが正常に完了しました。
SQL> print :cnt
CNT
----------
1
13.固定后来Load进来的执行计划。
SQL> exec :cnt := dbms_spm.alter_sql_plan_baseline(sql_handle => \'&sql_handle\', plan_name => \'&plan_name\', attribute_name => \'FIXED\', attribute_value => \'YES\');
sql_handleに値を入力してください: SQL_156e46a7ed64e33d
plan_nameに値を入力してください: SQL_PLAN_1avk6nzqq9stxfbe5cdec
PL/SQLプロシージャが正常に完了しました。
SQL> print :cnt
CNT
----------
1
SQL> select sql_handle,sql_text, plan_name,fixed from dba_sql_plan_baselines where sql_text like \'select count(*) from tab2 where c2=1\';
SQL_HANDLE SQL_TEXT PLAN_NAME FIX
------------------------------ -------------------------------------------------- ------------------------------ ---
SQL_156e46a7ed64e33d select count(*) from tab2 where c2=1 SQL_PLAN_1avk6nzqq9stxfbe5cdec YES
14.执行原始SQL文，再次查看SQLPLAN。
conn test/test@localhost:1521/pdb
set autot on
set lin 120 pages 999
select count(*) from tab2 where c2=1;
COUNT(*)
----------
50
実行計画
----------------------------------------------------------
Plan hash value: 2781695375
---------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
---------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 3 | 5 (0)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | 3 | | |
|* 2 | TABLE ACCESS FULL| TAB2 | 50 | 150 | 5 (0)| 00:00:01 |
---------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter("C2"=1)
Note
-----
- SQL plan baseline "SQL_PLAN_1avk6nzqq9stxfbe5cdec" used for this statement
統計
----------------------------------------------------------
118 recursive calls
41 db block gets
83 consistent gets
0 physical reads
4520 redo size
573 bytes sent via SQL*Net to client
398 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
4 sorts (memory)
0 sorts (disk)
1 rows processed
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