oracle 9i 性能调优3

九、Optimizing
Sort Operations

优化排序操作

1、PGA

show parameter pga_aggregate_target;

show parameter workarea_size_policy;

setting Initially PGA

For OLTP:

pga_aggregate_target=(total_mem*80%)*20%

For DSS:

pga_aggregate_target=(total_mem*80%)*50%

2、PGA Management Resources

1) Views for monitoring the PGA work area include:

-- v$sql_workarea_histogram

-- v$pagstat

-- v$sql_workarea_active

-- v$sql_workarea

-- v$tempseg_usage

2) Views to assist in sizing the PGA work area are:

-- v$pga_target_advice

-- v$pga_target_advice_histogram



select * from v$pgastat;

select * from v$sql_workarea_histogram;

select low_optimal_size/1024 "Low_kb",(high_optimal_size+1)/1024 "High_kb",

            round(100*optimal_executions/total_executions) "Optimal",

round(100*onepass_executions/total_executions) "One Pass",

round(100*multipasses_executions/total_executions) "Multi Pass"

from  v$sql_workarea_histogram

where total_executions != 0

order by "Low_kb";

select to_number(decode(sid,65535,null,sid)) sid,

operation_type Oper,

trunc(expected_size/1024) esize,

trunc(actual_mem_used/1024) mem,

trunc(max_mem_used/1024) "Max Mem",

number_passes pass

from v$sql_workarea_active

order by 1,2;

select sql_text,

sum(onepass_executions) onepass_cnt,

sum(multipasses_executions) mpass_cnt

from v$sql s, v$sql_workarea wa

where s.address = wa.address

group by sql_text

having sum(onepass_executions + multipasses_executions)>0;

3、PGA Target Advice Statistics

--v$pga_target_advice

select * from v$pga_target_advice;

v$sql_workarea_histogram;

show parameter sort_area_size;

4、Requiring Sorts

select * from v$sysstat where name like '%sort%';

Avoiding Sort



Diagnostic Tools

-- v$sort_usage

-- v$sort_segment

-- v$tempfile

-- dba_temp_file

十一、Using Resource Manager           --使用资源管理器

1、Create Simple Resource Plan

-- dbms_resource_manager

begin

dbms_resource_manager.create_simple_plan('linplan','grp1',80,'grp2',20);

end;

2、Assigning Privilege

-- dbms_resource_manager_privs

dbms_resource_manager_privs.grant_system_privilege

( grantee_name => 'OE',

   privilege_name => 'ADMINISTER_RESOURCE_MANAGER',

  admin_option => False);

3、Creating Complex RP

1) create a pending area

2) create,modify or delete consumer groups

3) create the resource plan

4) create resource plan directives

5) validate the pending area

6) submit the pending area

begin

dbms_resource_manager.create_pending_area();

end;

begin

dbms_resource_manager.create_consumer_group('my_oltp','this is my group');

end;

begin

dbms_resource_manager.create_plan('my_plan','this is my plan');

end;

begin

dbms_resource_manager.create_plan_directive('my_plan','my_oltp','xxxx',75);

end;

begin

dbms_resource_manager.create_plan_directive('my_plan','other_groups','xxxx',15);

end;

begin

dbms_resource_manager.validate_pending_area();

end;

begin

dbms_resource_manager.submit_pending_area();

end;

Assigning Users

4、Views and DDs

-- dba_rsrc_plans

-- dba_rsrc_plan_directives

-- dba_rsrc_consumer_groups

-- dba_rsrc_consumer_group_privs

-- dba_users中的INITIAL_RSRC_CONSUMER_GROUP列

-- dba_rsrc_manager_system_privs

-- v$session 中的resource_consumer_group列

-- v$rsrc_plan

-- v$rsrc_consumer_group

十一、SQL Statement Tuning    --SQL语句调优

1、Using Hints in SQL

select /*+ INDEX(customers gen_idx) */ cust_last_name,cust_street_address,cust_postal_code

from sh.customers where uper(cust_gender) = 'M';

2、Diagnostic Tools

* Statspack

* explain plan

* sql trace and tkprof

* sqlplus autotrace feature

* oracle sql analyze

3、Explain plan

SQL> @?/rdbms/admin/utlxplan.sql

SQL> explain plan for
  2  select employee_id,last_name,salary
  3  from hr.employees where employee_id=120;

Explained.

SQL> select count(*) from plan_table;

  COUNT(*)

----------

         3

* Use script utlxpls.sql (hide Parallel Query information)

* Use script
utlxplp.sql (show Parallel Query information)

* Use the
dbms_xplan package

SQL> @?/rdbms/admin/utlxpls.sql;

SQL> select * from table(dbms_xplan.display);

4、Using SQL Trace & TKPROF Formatting the Trace File

1. cd [ORACLE_HOME]/rdbms/admin

2. log into SQL*Plus as SYSTEM

3. Run @utlxplan

4. Run CREATE PUBLIC SYNONYM PLAN_TABLE FOR PLAN_TABLE;

5. Run GRANT ALL ON PLAN_TABLE TO PUBLIC;

1. cd [ORACLE_HOME]/sqlplus/admin

2. Log in to SQL*Plus as SYS or as SYSDBA

3. Run @plustrce

4. Run GRANT PLUSTRACE TO PUBLIC;

set autot on;

十二、Managing Statistics            --管理统计数据

1、 Managing Statistics



Use the dbms_stats package

* gather_table_stats

* gather_index_stats

* gather_schema_stats

* gather_database_stats

* gather_stale_stats

-- all_tables

-- all_indexes

-- user_tab_col_statistics

-- v$segstat_name

-- v$segstat

-- v$segment_statistics

SQL> select object_id from dba_objects where owner='HR' and object_name='T';    OBJECT_ID ----------      58134   SQL> select * from v$segstat where dataobj#=58134;          TS#       OBJ#   DATAOBJ# STATISTIC_NAME                                                   STATISTIC#      VALUE ---------- ---------- ---------- ---------------------------------------------------------------- ---------- ----------          4      58134      58134 logical reads                                                             0         64          4      58134      58134 buffer busy waits                                                         1          0          4      58134      58134 gc buffer busy                                                            2          0          4      58134      58134 db block changes                                                          3      12704          4      58134      58134 physical reads                                                            4        411          4      58134      58134 physical writes                                                           5        373          4      58134      58134 physical reads direct                                                     6          0          4      58134      58134 physical writes direct                                                    7          0          4      58134      58134 gc cr blocks received                                                     9          0          4      58134      58134 gc current blocks received                                               10          0          4      58134      58134 ITL waits                                                                11          0          4      58134      58134 row lock waits                                                           12          0          4      58134      58134 space used                                                               14          0          4      58134      58134 space allocated                                                          15          0          4      58134      58134 segment scans                                                            17          0   15 rows selected   SQL>

Enabling Dynamic Sampling

-- show parameter optimizer_dynamic_sampling

Histograms

-- dbms_stats.gather_table_stats

-- dba_histograms

-- dba_tab_histograms

exec dbms_stats.gather_table_stats('HR','T',method_opt=>'FOR COLUMNS SIZE 10 id');

Gathering System Statistics   (dbms_stats)

-- gather_system_stats

-- set_system_stats

-- get_system_stats

Collect statistics for OLTP:

execute dbms_stats.gather_system_stats(interval =>120,stattab=>'mystats',statid='OLTP')

Collect statistics for OLAP:

execute dbms_stats.gather_system_stats(interval =>120,stattab=>'mystats',statid='OLAP')

2、Copy Statistics Between DBs

example

1) create the table to hold the statistics:

dbms_stats.create_stat_table

('SH',STATS','SAMPLE');

 exec dbms_stats.create_stat_table('HR','MYSTATS');

2) Copy the statistics to a table

dbms_stats.export_table_stats

('SH','SALES',NULL,'STATS','CRS990601',TRUE);

3)Export the stats table and import it into the second database

4)Copy the statistics into the data dictionary

dbms_stats.import_table_stats

('SH','SALES',NULL,'STATS','CR990601',TRUE);