通过段调优顾问帮助解决行链接问题

Posted 2020-07-08 侯志清-江西南昌

--解决行链接问题
SQL> create tablespace hzqtbs datafile ‘/u01/app/oracle/oradata/prod/hzqtbs.dbf‘ size 600m;

Tablespace created.

SQL> create user hzq identified by hzq default tablespace hzqtbs quota unlimited on hzqtbs account unlock;

User created.

SQL> grant create session to hzq;

Grant succeeded.

SQL> grant resource to hzq;

Grant succeeded.

SQL> conn hzq/hzq
Connected.

create table test (id number,name varchar2(100));
begin
for i in  1..1000000 loop
insert into test values(i,‘user‘||i);
commit;
end loop;
end;
/
--通过更新使字段边长生成行链接
update test set name=‘userldsajflsadjfldsjfldsafdsahflsahfldsaflsajflkdajfjflajfldsakjflkdsajfldsajflsafjlasfadsafdsafsad‘;

--删除，重新收集手动运行顾问
DECLARE
BEGIN
dbms_advisor.delete_task (
task_name => ‘MYTEST Advice‘
);
END;
/

DECLARE
my_task_id number;
obj_id number;
my_task_name varchar2(100);
my_task_desc varchar2(500);
BEGIN
my_task_name := ‘MYTEST Advice‘;
my_task_desc := ‘Manual Segment Advisor Run‘;
---------
-- Step 1 create a task
---------
dbms_advisor.create_task (
advisor_name => ‘Segment Advisor‘,
task_id => my_task_id,
task_name => my_task_name,
task_desc => my_task_desc);
---------
-- Step 2 create a object
---------
dbms_advisor.create_object (
task_name => my_task_name,
object_type => ‘TABLE‘,
attr1 => ‘HZQ‘,
attr2 => ‘TEST‘,
attr3 => NULL,
attr4 => NULL,
attr5 => NULL,
object_id => obj_id);
---------
-- Step 3
---------
dbms_advisor.set_task_parameter(
task_name => my_task_name,
parameter => ‘recommend_all‘,
value => ‘TRUE‘);
---------
-- Step 4
---------
dbms_advisor.execute_task(my_task_name);
END;
/

--查看看行链接问题
SELECT
‘Task Name : ‘ || f.task_name || chr(10) ||
‘Segment Name : ‘ || o.attr2 || chr(10) ||
‘Segment Type : ‘ || o.type || chr(10) ||
‘Partition Name : ‘ || o.attr3 || chr(10) ||
‘Message : ‘ || f.message || chr(10) ||
‘More Info : ‘ || f.more_info TASK_ADVICE
FROM dba_advisor_findings f
,dba_advisor_objects o
WHERE o.task_id = f.task_id
AND o.object_id = f.object_id
ORDER BY f.task_name;

select
‘Task Name : ‘ || f.task_name || chr(10) ||
‘Start Run Time : ‘ || TO_CHAR(execution_start, ‘dd-mon-yy hh24:mi‘) || chr (10) ||
‘Segment Name : ‘ || o.attr2 || chr(10) ||
‘Segment Type : ‘ || o.type || chr(10) ||
‘Partition Name : ‘ || o.attr3 || chr(10) ||
‘Message : ‘ || f.message || chr(10) ||
‘More Info : ‘ || f.more_info || chr(10) ||
‘------------------------------------------------------‘ Advice
FROM dba_advisor_findings f
,dba_advisor_objects o
,dba_advisor_executions e
WHERE o.task_id = f.task_id
AND o.object_id = f.object_id
AND f.task_id = e.task_id
AND e. execution_start > sysdate - 1
AND e.advisor_name = ‘Segment Advisor‘
ORDER BY f.task_name;

ADVICE
----------------------------
Task Name : MYTEST Advice
Start Run Time : 18-may-16 22:53
Segment Name : TEST
Segment Type : TABLE
Partition Name :
Message : The free space in the object is less than 10MB.
More Info : Allocated Space:167772160: Used Space:165481507: Reclaimable Space :2290653:
------------------------------------------------------

Task Name : MYTEST Advice
Start Run Time : 18-may-16 22:53

ADVICE
-------------------------------------------------------
Segment Name : TEST
Segment Type : TABLE
Partition Name :
Message : The object has chained rows that can be removed by re-org.
More Info : 46 percent chained rows can be removed by re-org.

--有46%的行链接可以被remove，解决行链接的方法是通过move表来实现，但是表move后表的索引会失效，需要重建索引，行移动需要很多的表空间，建议表空间空余空间大于表的大小。
SQL> create index idx_test on test(id);

Index created.

SQL> conn / as sysdba
Connected.
SQL> select owner,index_name,status from dba_indexes where table_name=‘TEST‘;

OWNER                   INDEX_NAME              STATUS
------------------------------ ------------------------------ --------
HZQ                   IDX_TEST               UNUSABLE

SQL> alter index hzq.IDX_TEST rebuild;

Index altered.

--删除，重新收集手动运行顾问
DECLARE
BEGIN
dbms_advisor.delete_task (
task_name => ‘MYTEST Advice‘
);
END;
/

DECLARE
my_task_id number;
obj_id number;
my_task_name varchar2(100);
my_task_desc varchar2(500);
BEGIN
my_task_name := ‘MYTEST Advice‘;
my_task_desc := ‘Manual Segment Advisor Run‘;
---------
-- Step 1 create a task
---------
dbms_advisor.create_task (
advisor_name => ‘Segment Advisor‘,
task_id => my_task_id,
task_name => my_task_name,
task_desc => my_task_desc);
---------
-- Step 2 create a object
---------
dbms_advisor.create_object (
task_name => my_task_name,
object_type => ‘TABLE‘,
attr1 => ‘HZQ‘,
attr2 => ‘TEST‘,
attr3 => NULL,
attr4 => NULL,
attr5 => NULL,
object_id => obj_id);
---------
-- Step 3
---------
dbms_advisor.set_task_parameter(
task_name => my_task_name,
parameter => ‘recommend_all‘,
value => ‘TRUE‘);
---------
-- Step 4
---------
dbms_advisor.execute_task(my_task_name);
END;
/

SQL> select
‘Task Name : ‘ || f.task_name || chr(10) ||
‘Start Run Time : ‘ || TO_CHAR(execution_start, ‘dd-mon-yy hh24:mi‘) || chr (10) ||
‘Segment Name : ‘ || o.attr2 || chr(10) ||
‘Segment Type : ‘ || o.type || chr(10) ||
‘Partition Name : ‘ || o.attr3 || ch  2    3    4    5    6  r(10) ||
‘Message : ‘ || f.message || chr(10) ||
‘More Info : ‘ || f.more_info || chr(10) ||
‘------------------------------------------------------‘ Advice
FROM dba_advisor_findings f
,dba_advisor_objects o
,dba_advisor_executions e
WHERE o.task_id = f.ta  7    8    9   10   11   12   13  sk_id
AND o.object_id = f.object_id
AND f.task_id = e.task_id
AND e. execution_start > sysdate - 1
AND e.advisor_name = ‘Segment Advisor‘
ORDER BY f.task_name; 14   15   16   17   18  

ADVICE
----------------------------------------------------
Task Name : MYTEST Advice
Start Run Time : 18-may-16 23:07
Segment Name : TEST
Segment Type : TABLE
Partition Name :
Message : The free space in the object is less than 10MB.
More Info : Allocated Space:134217728: Used Space:126002153: Reclaimable Space :8215575:
------------------------------------------------------

--结果没有显示行链接问题