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Oracle性能优化——SQL基线(SQLbaseline)的载入与进化(11g中引入的基线)

程序员文章站 2023-10-11 17:46:22
oracle性能优化——sql基线(sqlbaseline)的载入与进化(11g中引入的基线) sys@ prod> conn sh/sh connected....

oracle性能优化——sql基线(sqlbaseline)的载入与进化(11g中引入的基线)

sys@ prod> conn sh/sh
connected.
执行想要创建基线的语句,语句的执行计划将会被缓存
sh@ prod> set autotrace on
sh@ prod> select /*ghbaselines1*/ count(*) from customers join countries using ( country_id ) 
  2  where country_name = 'new zealand' and cust_income_level = 'g: 130,000 - 149,999' 
  3  and cust_year_of_birth < '1952' ;

  count(*)
----------
         9


execution plan
----------------------------------------------------------
plan hash value: 3580706376

---------------------------------------------------------------------------------
| id  | operation           | name      | rows  | bytes | cost (%cpu)| time     |
---------------------------------------------------------------------------------
|   0 | select statement    |           |     1 |    45 |   409   (1)| 00:00:05 |
|   1 |  sort aggregate     |           |     1 |    45 |            |          |
|*  2 |   hash join         |           |   123 |  5535 |   409   (1)| 00:00:05 |
|*  3 |    table access full| countries |     1 |    15 |     3   (0)| 00:00:01 |
|*  4 |    table access full| customers |  2341 | 70230 |   405   (1)| 00:00:05 |
---------------------------------------------------------------------------------

predicate information (identified by operation id):
---------------------------------------------------

   2 - access("customers"."country_id"="countries"."country_id")
   3 - filter("countries"."country_name"='new zealand')
   4 - filter("customers"."cust_income_level"='g: 130,000 - 149,999' and
              "customers"."cust_year_of_birth"<1952)


statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
       1462  consistent gets
         19  physical reads
          0  redo size
        526  bytes sent via sql*net to client
        523  bytes received via sql*net from client
          2  sql*net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed

从游标缓存区中手动载入关于这个sql的执行计划做为基线
sh@ prod> conn / as sysdba
connected.
sys@ prod> declare
  2  v_sql_id v$sql.sql_id%type ;
  3  v_plan_count number ;
  4  begin
  5  select sql_id into v_sql_id from v$sql
  6  where sql_text like 'select /*ghbaselines1*/%' ;
  7  
  8  v_plan_count := dbms_spm.load_plans_from_cursor_cache( sql_id => v_sql_id ) ;
  9  dbms_output.put_line( v_plan_count || ' plans loaded' ) ;
 10  end ;
 11  /
1 plans loaded

pl/sql procedure successfully completed.

查看基线的信息,这个基线的状态是accepted,是将会被优化器使用的
sys@ prod> select sql_handle , plan_name , origin , accepted , optimizer_cost as cost
  2  from dba_sql_plan_baselines
  3  where sql_text like 'select /*ghbaselines1*/%' ;

sql_handle                     plan_name                      origin         acc       cost
------------------------------ ------------------------------ -------------- --- ----------
sys_sql_a8f88a44571be8dd       sql_plan_ajy4a8jbjru6x0e60872e manual-load    yes        409

查看基线里面的执行计划
sys@ prod> var v_sql_handle varchar2(50) ; 
sys@ prod> exec :v_sql_handle := 'sys_sql_a8f88a44571be8dd' ;

pl/sql procedure successfully completed.

sys@ prod> select * from table(dbms_xplan.display_sql_plan_baseline(:v_sql_handle , null , 'basic' ) ) ;

plan_table_output
------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------
sql handle: sys_sql_a8f88a44571be8dd
sql text: select /*ghbaselines1*/ count(*) from customers join countries using (
          country_id ) where country_name = 'new zealand' and cust_income_level =
          'g: 130,000 - 149,999' and cust_year_of_birth < '1952'
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
plan name: sql_plan_ajy4a8jbjru6x0e60872e         plan id: 241207086
enabled: yes     fixed: no      accepted: yes     origin: manual-load
--------------------------------------------------------------------------------

plan hash value: 3580706376

-----------------------------------------
| id  | operation           | name      |
-----------------------------------------
|   0 | select statement    |           |
|   1 |  sort aggregate     |           |
|   2 |   hash join         |           |
|   3 |    table access full| countries |
|   4 |    table access full| customers |
-----------------------------------------

24 rows selected.

创建索引
sys@ prod> conn sh/sh
connected.
sh@ prod> create index cust_country_index_dob_ix on 
  2  customers( country_id , cust_income_level , cust_year_of_birth ) ;

index created.

查看执行计划是否有变化,因为基线的存在执行计划并没有变化,执行计划获得了稳定
sh@ prod> set autotrace on
sh@ prod> select /*ghbaselines1*/ count(*) from customers join countries using ( country_id ) 
  2  where country_name = 'new zealand' and cust_income_level = 'g: 130,000 - 149,999' 
  3  and cust_year_of_birth < '1952' ;

  count(*)
----------
         9


execution plan
----------------------------------------------------------
plan hash value: 3580706376

---------------------------------------------------------------------------------
| id  | operation           | name      | rows  | bytes | cost (%cpu)| time     |
---------------------------------------------------------------------------------
|   0 | select statement    |           |     1 |    45 |   409   (1)| 00:00:05 |
|   1 |  sort aggregate     |           |     1 |    45 |            |          |
|*  2 |   hash join         |           |   123 |  5535 |   409   (1)| 00:00:05 |
|*  3 |    table access full| countries |     1 |    15 |     3   (0)| 00:00:01 |
|*  4 |    table access full| customers |  2341 | 70230 |   405   (1)| 00:00:05 |
---------------------------------------------------------------------------------

predicate information (identified by operation id):
---------------------------------------------------

   2 - access("customers"."country_id"="countries"."country_id")
   3 - filter("countries"."country_name"='new zealand')
   4 - filter("customers"."cust_income_level"='g: 130,000 - 149,999' and
              "customers"."cust_year_of_birth"<1952)

note
-----
   - sql plan baseline "sql_plan_ajy4a8jbjru6x0e60872e" used for this statement


statistics
----------------------------------------------------------
        537  recursive calls
         37  db block gets
       1555  consistent gets
          1  physical reads
      14388  redo size
        526  bytes sent via sql*net to client
        523  bytes received via sql*net from client
          2  sql*net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed

查看新的基线(新的执行计划由优化器生成,但是由于基线的存在并没有被使用,即使更好,但是会生成一个新的基线)
两个基线的sql_handle是一样的。
sh@ prod> conn / as sysdba
connected.
sys@ prod> select sql_handle , plan_name , origin , accepted , optimizer_cost as cost
  2  from dba_sql_plan_baselines
  3  where sql_text like 'select /*ghbaselines1*/%' ;

sql_handle                     plan_name                      origin         acc       cost
------------------------------ ------------------------------ -------------- --- ----------
sys_sql_a8f88a44571be8dd       sql_plan_ajy4a8jbjru6x0e60872e manual-load    yes        409
sys_sql_a8f88a44571be8dd       sql_plan_ajy4a8jbjru6x5b4b1285 auto-capture   no           5

进化基线,verify为yes表示对性能有提升才会被接受。commit表示直接接受,而不是给出建议。
sys@ prod> var v_sql_handle varchar2(50)
sys@ prod> exec :v_sql_handle := 'sys_sql_a8f88a44571be8dd' 
sys@ prod> var v_report varchar2(2000) 
sys@ prod> begin
  2  :v_report := dbms_spm.evolve_sql_plan_baseline ( sql_handle => :v_sql_handle , 
  3  verify => 'yes' ,
  4  commit => 'yes' ) ;
  5  end ;
  6  /

pl/sql procedure successfully completed.

查看报告
sys@ prod> set serveroutput on 
sys@ prod> exec dbms_output.put_line(:v_report ) ;

-------------------------------------------------------------------------------
                        evolve sql plan
baseline report
-------------------------------------------------------------------------------

inputs:
-------

sql_handle = sys_sql_a8f88a44571be8dd
  plan_name  = 
  time_limit = dbms_spm.auto_limit
  verify     = yes
  commit
= yes

plan: sql_plan_ajy4a8jbjru6x5b4b1285
------------------------------------
  plan was verified: time used .08
seconds.
  plan passed performance criterion: 243.74 times better than baseline plan.
  plan was changed to an accepted
plan.

                            baseline plan      test plan       stats ratio

-------------      ---------       -----------
  execution status:              complete       complete
  rows
processed:                       1              1
  elapsed time(ms):                 4.647           .043
108.07
  cpu time(ms):                     4.554              0
  buffer gets:                       1462              6
243.67
  physical read requests:               0              0
  physical write requests:              0
0
  physical read bytes:                  0              0
  physical write bytes:                 0              0

executions:                           1
1

-------------------------------------------------------------------------------

report summary
-------------------------------------------------------------------------------
number of plans verified:
1
number of plans accepted: 1

pl/sql procedure successfully completed.

查看进化后的基线是否生效,结果表明执行计划在稳定的基础上获得了提升
sys@ prod> conn sh/sh
connected.
sh@ prod> set autotrace on
sh@ prod> select /*ghbaselines1*/ count(*) from customers join countries using ( country_id ) 
  2  where country_name = 'new zealand' and cust_income_level = 'g: 130,000 - 149,999' 
  3  and cust_year_of_birth < '1952' ;

  count(*)
----------
         9


execution plan
----------------------------------------------------------
plan hash value: 1428720438

-------------------------------------------------------------------------------------------------
| id  | operation           | name                      | rows  | bytes | cost (%cpu)| time     |
-------------------------------------------------------------------------------------------------
|   0 | select statement    |                           |     1 |    45 |     5   (0)| 00:00:01 |
|   1 |  sort aggregate     |                           |     1 |    45 |            |          |
|   2 |   nested loops      |                           |   123 |  5535 |     5   (0)| 00:00:01 |
|*  3 |    table access full| countries                 |     1 |    15 |     3   (0)| 00:00:01 |
|*  4 |    index range scan | cust_country_index_dob_ix |   123 |  3690 |     2   (0)| 00:00:01 |
-------------------------------------------------------------------------------------------------

predicate information (identified by operation id):
---------------------------------------------------

   3 - filter("countries"."country_name"='new zealand')
   4 - access("customers"."country_id"="countries"."country_id" and
              "customers"."cust_income_level"='g: 130,000 - 149,999' and
              "customers"."cust_year_of_birth"<1952)

note
-----
   - sql plan baseline "sql_plan_ajy4a8jbjru6x5b4b1285" used for this statement


statistics
----------------------------------------------------------
         14  recursive calls
         14  db block gets
         14  consistent gets
          0  physical reads
       3040  redo size
        526  bytes sent via sql*net to client
        523  bytes received via sql*net from client
          2  sql*net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
1rows processed

查看新的基线信息,两个都是接受的,但是oracle当然会选cost小的
sys@ prod> select sql_handle , plan_name , origin , accepted , optimizer_cost as cost
  2  from dba_sql_plan_baselines
  3  where sql_text like 'select /*ghbaselines1*/%' ;

sql_handle                     plan_name                      origin         acc       cost
------------------------------ ------------------------------ -------------- --- ----------
sys_sql_a8f88a44571be8dd       sql_plan_ajy4a8jbjru6x0e60872e manual-load    yes        409
sys_sql_a8f88a44571be8dd       sql_plan_ajy4a8jbjru6x5b4b1285 auto-capture   yes          5

查看基线的执行计划,两个都会被展示
sys@ prod> select * from table(dbms_xplan.display_sql_plan_baseline('sys_sql_a8f88a44571be8dd' , null , 'basic' ) ) ;

plan_table_output
------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------
sql handle: sys_sql_a8f88a44571be8dd
sql text: select /*ghbaselines1*/ count(*) from customers join countries using (
          country_id ) where country_name = 'new zealand' and cust_income_level =
          'g: 130,000 - 149,999' and cust_year_of_birth < '1952'
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
plan name: sql_plan_ajy4a8jbjru6x0e60872e         plan id: 241207086
enabled: yes     fixed: no      accepted: yes     origin: manual-load
--------------------------------------------------------------------------------

plan hash value: 3580706376

-----------------------------------------
| id  | operation           | name      |
-----------------------------------------
|   0 | select statement    |           |
|   1 |  sort aggregate     |           |
|   2 |   hash join         |           |
|   3 |    table access full| countries |
|   4 |    table access full| customers |
-----------------------------------------

--------------------------------------------------------------------------------
plan name: sql_plan_ajy4a8jbjru6x5b4b1285         plan id: 1531646597

plan_table_output
------------------------------------------------------------------------------------------------------------------------
enabled: yes     fixed: no      accepted: yes     origin: auto-capture
--------------------------------------------------------------------------------

plan hash value: 1428720438

---------------------------------------------------------
| id  | operation           | name                      |
---------------------------------------------------------
|   0 | select statement    |                           |
|   1 |  sort aggregate     |                           |
|   2 |   nested loops      |                           |
|   3 |    table access full| countries                 |
|   4 |    index range scan | cust_country_index_dob_ix |
---------------------------------------------------------

41 rows selected.