根据metalink脚本学习undo（三）
UndoUsage.sql 关于UNDO使用率 使用状态的脚本
set lines 120
set pages 999
clear col
set termout off
set trimout on
set trimspool on
connect / as sysdba
alter session set nls_date_format='dd-Mon-yyyy hh24:mi';
spool undousage.out
prompt
prompt ############## RUNTIME ##############
prompt
col rdate head "Run Time"
select sysdate rdate from dual;
prompt
prompt ############## IN USE Undo Data ##############
prompt
--undo 使用率
select
((select (nvl(sum(bytes),0))
from dba_undo_extents
where tablespace_name in (select tablespace_name from dba_tablespaces
where retention like '%GUARANTEE' )
and status in ('ACTIVE','UNEXPIRED')) *100) /
(select sum(bytes)
from dba_data_files
where tablespace_name in (select tablespace_name from dba_tablespaces
where retention like '%GUARANTEE' )) "PCT_INUSE"
from dual;
--undo 表空间信息
select tablespace_name, --undo表空间名称
extent_management, --extent 管理模式
allocation_type, --分配方式 SYSTEM UNIFORM USER
segment_space_management, --段管理方式
retention -- GUARANTEE undo 表空间声明为GUARANTEE 强制保留undo信息到undo_RETENTION
-- GUARANTEE undo 表空间声明为NOGUARANTEE 尽量保留undo信息到undo_RETENTION
-- NOT APPLY 非undo 表空间
from dba_tablespaces where retention like '%GUARANTEE'
/
col c format 999,999,999,999 head "Sum of Free"
select (nvl(sum(bytes),0)) c from dba_free_space --剩余空间
where tablespace_name in
(select tablespace_name from dba_tablespaces where retention like '%GUARANTEE')
/
col d format 999,999,999,999 head "Total Bytes"
select sum(bytes) d from dba_data_files --表空间大小
where tablespace_name in
(select tablespace_name from dba_tablespaces where retention like '%GUARANTEE')
/
PROMPT
PROMPT ############## UNDO SEGMENTS ##############
PROMPT
col status head "Status"
col z format 999,999 head "Total Extents"
break on report
compute sum on report of z
select status, count(*) z --表各状态空间区数量
from dba_undo_extents
group by status
/
col z format 999,999 head "Undo Segments"
select status, count(*) z --表空间各状态回滚段数量
from dba_rollback_segs
group by status
/
clear break
clear compute
prompt
prompt ############## CURRENT STATUS OF SEGMENTS ##############
prompt ############## SNAPSHOT IN TIME INFO ##############
prompt ##############(SHOWS CURRENT UNDO ACTIVITY)##############
prompt
col segment_name format a30 head "Segment Name"
col "ACT BYTES" format 999,999,999,999 head "Active Bytes"
col "UNEXP BYTES" format 999,999,999,999 head "Unexpired Bytes"
col "EXP BYTES" format 999,999,999,999 head "Expired Bytes"
select segment_name,
nvl(sum(act), 0) "ACT BYTES",
nvl(sum(unexp), 0) "UNEXP BYTES",
nvl(sum(exp), 0) "EXP BYTES"
from (select segment_name, nvl(sum(bytes), 0) act, 00 unexp, 00 exp
from dba_undo_extents
where status = 'ACTIVE'
group by segment_name
union
select segment_name, 00 act, nvl(sum(bytes), 0) unexp, 00 exp
from dba_undo_extents
where status = 'UNEXPIRED'
group by segment_name
union
select segment_name, 00 act, 00 unexp, nvl(sum(bytes), 0) exp
from dba_undo_extents
where status = 'EXPIRED'
group by segment_name)
group by segment_name
order by 1
/
--我自己改写了一下
select segment_name,
sum(case
when status = 'ACTIVE' then
bytes
else
0
end) "ACT BYTES", --活动状态的区大小
sum(case
when status = 'UNEXPIRED' then
bytes
else
0
end) "UNEXP BYTES" , --未过期区大小
sum(case
when status = 'EXPIRED' then
bytes
else
0
end) "EXP BYTES" --过期区大小
from dba_undo_extents
group by segment_name
order by 1
prompt
prompt ############## UNDO SPACE USAGE ##############
prompt
col usn format 999,999 head "Segment#"
col shrinks format 999,999,999 head "Shrinks"
col aveshrink format 999,999,999 head "Avg Shrink Size"
select usn, --回滚段编号
shrinks, --回滚段收缩次数
aveshrink --平均每次收缩的大小
from v$rollstat
/
spool off
set termout on
set trimout off
set trimspool off
clear col
--UNEXPIRED --事务已经提交 但提交时间尚未达到undo_RETENTION
--EXPIRED --事务已经提交 但提交时间已经达到undo_RETENTION