How to use segment advisor

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1、查看segment advisor

方法一：

select * fromtable(dbms_space.asa_recommendations('TRUE','FALSE','FALSE'));

dbms_space.asa_recommentdations的三个参数：

all_runs TURE返回历次运行的结果，FALSE则返回最近一次运行的结果

show_manual TURE返回手工执行segment advisor的执行结果，FALSE返回自动执行的segment advisor的执行结果

show_finding TURE仅显示结果不显示建议，FALSE显示结果和建议

方法二：

select f.task_name,

execution_start,

o.attr2,

o.type,

o.attr3,

f.message,

f.more_info

from dba_advisor_executions e,

dba_advisor_findings f,

dba_advisor_objects o

where o.task_id = f.task_id

and o.object_id = f.object_id

and f.task_id = e.task_id

and e.advisor_name = 'Segment Advisor'

order by f.task_name;

segment advisor会自动的定期执行，查看其执行情况的视图是dba_auto_segadv_summary

查看ora advisor的视图

dba_advisor_executions

dba_advisor_findings

dba_advisor_objects

2、手工生成segment advisor

查看advisor name

select * fromdba_advisor_definitions;

ADVISOR_IDADVISOR_NAME PROPERTY

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

1 ADDM 1

2 SQL Access Advisor 271

3 Undo Advisor 1

4 SQL Tuning Advisor 935

5 Segment Advisor 67

6 SQL Workload Manager 0

7 Tune MView 31

8 SQL Performance Analyzer 935

9 SQL Repair Advisor 679

10 Compression Advisor 3

生成segmentadvisor

DECLARE

my_task_id number;

obj_id number;

my_task_name varchar2(100);

my_task_desc varchar2(500);

BEGIN

my_task_name := 'BIG_TABLE Advice';

my_task_desc := 'Manual Segment Advisor Run';

-- Step 1创建一个任务

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为这个任务分配一个对象

dbms_advisor.create_object(task_name => my_task_name,

object_type =>'TABLE',

attr1 => 'SYSTEM',

attr2 => 'AL_APPLY',

attr3 => NULL,

attr4 => NULL,

attr5 => NULL,

object_id => obj_id);

-- Step 3设置任务参数

dbms_advisor.set_task_parameter(task_name=> my_task_name,

parameter=> 'recommend_all',

value => 'TRUE');

-- Step 4执行这个任务

dbms_advisor.execute_task(my_task_name);

END;

说明：

Table 14-2 DBMS_ADVISOR packageprocedures relevant to the Segment Advisor

Package Procedure Name

Description

CREATE_TASK

Use this procedure to create the Segment Advisor task. Specify 'Segment Advisor' as the value of the ADVISOR_NAME parameter.

CREATE_OBJECT

Use this procedure to identify the target object for segment space advice. The parameter values of this procedure depend upon the object type. Table 14-3 lists the parameter values for each type of object.

Note: To request advice on an IOT overflow segment, use an object type of TABLE, TABLE PARTITION, or TABLE SUBPARTITION. Use the following query to find the overflow segment for an IOT and to determine the overflow segment table name to use with CREATE_OBJECT:

select table_name, iot_name, iot_type from dba_tables;

SET_TASK_PARAMETER

Use this procedure to describe the segment advice that you need. Table 14-4 shows the relevant input parameters of this procedure. Parameters not listed here are not used by the Segment Advisor.

EXECUTE_TASK

Use this procedure to execute the Segment Advisor task.

Table 14-3 Input forDBMS_ADVISOR.CREATE_OBJECT

Input Parameter

OBJECT_TYPE

ATTR1

ATTR2

ATTR3

ATTR4

TABLESPACE

tablespace name

NULL

Unused. Specify NULL.

TABLE

schema name

table name

NULL

Unused. Specify NULL.

INDEX

schema name

index name

NULL

Unused. Specify NULL.

TABLE PARTITION

schema name

table name

table partition name

Unused. Specify NULL.

INDEX PARTITION

schema name

index name

index partition name

Unused. Specify NULL.

TABLE SUBPARTITION

schema name

table name

table subpartition name

Unused. Specify NULL.

INDEX SUBPARTITION

schema name

index name

index subpartition name

Unused. Specify NULL.

LOB

schema name

segment name

NULL

Unused. Specify NULL.

LOB PARTITION

schema name

segment name

lob partition name

Unused. Specify NULL.

LOB SUBPARTITION

schema name

segment name

lob subpartition name

Unused. Specify NULL.

Table 14-4 Input forDBMS_ADVISOR.SET_TASK_PARAMETER

Input Parameter

Description

Possible Values

Default Value

time_limit

The time limit for the Segment Advisor run, specified in seconds.

Any number of seconds

UNLIMITED

recommend_all

Whether the Segment Advisor should generate findings for all segments.

TRUE: Findings are generated on all segments specified, whether or not space reclamation is recommended.

FALSE: Findings are generated only for those objects that generate recommendations for space reclamation.

TRUE

Example:

variable id number;
begin
declare
name varchar2(100);
descr varchar2(500);
obj_id number;
begin
name:='Manual_Employees';
descr:='Segment Advisor Example';

dbms_advisor.create_task (
    advisor_name     => 'Segment Advisor',
    task_id          => :id,
    task_name        => name,
    task_desc        => descr);

dbms_advisor.create_object (
    task_name        => name,
    object_type      => 'TABLE',
    attr1            => 'HR',
    attr2            => 'EMPLOYEES',
    attr3            => NULL,
    attr4            => NULL,
    attr5            => NULL,
    object_id        => obj_id);

dbms_advisor.set_task_parameter(
    task_name        => name,
    parameter        => 'recommend_all',
    value            => 'TRUE');

dbms_advisor.execute_task(name);
end;
end;
/

查看segmentadvisor结果

SELECT

'Segment Advice --------------------------'||chr(10) ||

'TABLESPACE_NAME : ' || tablespace_name || chr(10) ||

'SEGMENT_OWNER : ' || segment_owner || chr(10) ||

'SEGMENT_NAME : ' || segment_name || chr(10) ||

'ALLOCATED_SPACE : ' || allocated_space || chr(10) ||

'RECLAIMABLE_SPACE: ' || reclaimable_space ||chr(10) ||

'RECOMMENDATIONS : ' || recommendations || chr(10) ||

'SOLUTION 1 : ' || c1 || chr(10) ||

'SOLUTION 2 : ' || c2 || chr(10) ||

'SOLUTION 3 : ' || c3 Advice

FROM

TABLE(dbms_space.asa_recommendations('TRUE','TRUE', 'FALSE'));

或者：

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

FROMdba_advisor_findings f

,dba_advisor_objects o

WHERE o.task_id =f.task_id

AND o.object_id =f.object_id

AND f.task_name like'BIG_TABLE Advice'

ORDER BYf.task_name;

删除segmentadvisor

execdbms_advisor.delete_task('BIG_TABLE Advice');

释放未使用的表的空间

alter tabletablename enable rowmovement;

alter tabletablename shrink spcace;

alter table tablename shrink spcace cascade;(级联收缩索引空间)

alter table tablename shrink spcace compact;(只整理碎片，不调整高水位线)--如果整理碎片和降低高水位话费时间会很长，用于分开操作

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