通过ASH分析Oracle数据库的历史性能问题
Posted bisal(Chen Liu)
tags:
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Oracle中国的官方博客，还是有很多好文章值得借鉴，短小精悍的风格，例如这篇《如何通过dba_hist_active_sess_history分析数据库历史性能问题》，就介绍了排查性能问题的一种常用手段，可以放在我们的工具箱中。
P. S. 原文链接，
https://blogs.oracle.com/database4cn/post/dbahistactivesesshistory
SQL> conn user/passwd
SQL> create table t_ash as select * from dba_hist_active_sess_history where SAMPLE_TIME between TO_TIMESTAMP ('<time_begin>', 'YYYY-MM-DD HH24:MI:SS') and TO_TIMESTAMP ('<time_end>', 'YYYY-MM-DD HH24:MI:SS');
$ exp user/passwd file=t_ash.dmp tables=(t_ash) log=t_ash.exp.log然后导入到测试机，
$ imp user/passwd file=t_ash.dmp log=t_ash.imp.log
set line 200 pages 1000
col sample_time for a25
col event for a40
alter session set nls_timestamp_format='yyyy-mm-dd hh24:mi:ss.ff';
select
t.dbid, t.instance_number, min(sample_time), max(sample_time), count(*) session_count
from t_ash t
group by t.dbid, t.instance_number
order by dbid, instance_number;
INSTANCE_NUMBER MIN(SAMPLE_TIME) MAX(SAMPLE_TIME) SESSION_COUNT
1 2015-03-26 21:00:04.278 2015-03-26 22:59:48.387 2171
2 2015-03-26 21:02:12.047 2015-03-26 22:59:42.584 36
select
dbid, instance_number, sample_id, sample_time, count(*) session_count
from t_ash t
group by dbid, instance_number, sample_id, sample_time
order by dbid, instance_number, sample_time;
INSTANCE_NUMBER SAMPLE_ID SAMPLE_TIME SESSION_COUNT
1 36402900 2015-03-26 22:02:50.985 4
1 36402910 2015-03-26 22:03:01.095 1
1 36402920 2015-03-26 22:03:11.195 1
1 36402930 2015-03-26 22:03:21.966 21
1 36402940 2015-03-26 22:03:32.116 102
1 36402950 2015-03-26 22:03:42.226 181
1 36402960 2015-03-26 22:03:52.326 200
1 36402970 2015-03-26 22:04:02.446 227
1 36402980 2015-03-26 22:04:12.566 242
1 36402990 2015-03-26 22:04:22.666 259
1 36403000 2015-03-26 22:04:32.846 289
1 36403010 2015-03-26 22:04:42.966 147
1 36403020 2015-03-26 22:04:53.076 2
1 36403030 2015-03-26 22:05:03.186 4
1 36403040 2015-03-26 22:05:13.296 1
1 36403050 2015-03-26 22:05:23.398 1
select t.dbid,
t.sample_id,
t.sample_time,
t.instance_number,
t.event,
t.session_state,
t.c session_count
from (select t.*,
rank() over(partition by dbid, instance_number, sample_time order by c desc) r
from (select
t.*,
count(*) over(partition by dbid, instance_number, sample_time, event) c,
row_number() over(partition by dbid, instance_number, sample_time, event order by 1) r1
from t_ash t
/*where sample_time >
to_timestamp('2013-11-17 13:59:00',
'yyyy-mm-dd hh24:mi:ss')
and sample_time <
to_timestamp('2013-11-17 14:10:00',
'yyyy-mm-dd hh24:mi:ss')*/
) t
where r1 = 1) t
where r < 3
order by dbid, instance_number, sample_time, r;
SAMPLE_ID SAMPLE_TIME INSTANCE_NUMBER EVENT SESSION_STATE SESSION_COUNT
36402900 22:02:50.985 1 ON CPU 3
36402900 22:02:50.985 1 db file sequential read WAITING 1
36402910 22:03:01.095 1 ON CPU 1
36402920 22:03:11.195 1 db file parallel read WAITING 1
36402930 22:03:21.966 1 cursor: pin S wait on X WAITING 11
36402930 22:03:21.966 1 latch: shared pool WAITING 4
36402940 22:03:32.116 1 cursor: pin S wait on X WAITING 83
36402940 22:03:32.116 1 SGA: allocation forcing component growth WAITING 16
36402950 22:03:42.226 1 cursor: pin S wait on X WAITING 161
36402950 22:03:42.226 1 SGA: allocation forcing component growth WAITING 17
36402960 22:03:52.326 1 cursor: pin S wait on X WAITING 177
36402960 22:03:52.326 1 SGA: allocation forcing component growth WAITING 20
36402970 22:04:02.446 1 cursor: pin S wait on X WAITING 204
36402970 22:04:02.446 1 SGA: allocation forcing component growth WAITING 20
36402980 22:04:12.566 1 cursor: pin S wait on X WAITING 219
36402980 22:04:12.566 1 SGA: allocation forcing component growth WAITING 20
36402990 22:04:22.666 1 cursor: pin S wait on X WAITING 236
36402990 22:04:22.666 1 SGA: allocation forcing component growth WAITING 20
36403000 22:04:32.846 1 cursor: pin S wait on X WAITING 265
36403000 22:04:32.846 1 SGA: allocation forcing component growth WAITING 20
36403010 22:04:42.966 1 enq: US - contention WAITING 69
36403010 22:04:42.966 1 latch: row cache objects WAITING 56
36403020 22:04:53.076 1 db file scattered read WAITING 1
36403020 22:04:53.076 1 db file sequential read WAITING 1
select
level lv,
connect_by_isleaf isleaf,
connect_by_iscycle iscycle,
t.dbid,
t.sample_id,
t.sample_time,
t.instance_number,
t.session_id,
t.sql_id,
t.session_type,
t.event,
t.session_state,
t.blocking_inst_id,
t.blocking_session,
t.blocking_session_status
from t_ash t
/*where sample_time >
to_timestamp('2013-11-17 13:55:00',
'yyyy-mm-dd hh24:mi:ss')
and sample_time <
to_timestamp('2013-11-17 14:10:00',
'yyyy-mm-dd hh24:mi:ss')*/
start with blocking_session is not null
connect by nocycle
prior dbid = dbid
and prior sample_time = sample_time
/*and ((prior sample_time) - sample_time between interval '-1'
second and interval '1' second)*/
and prior blocking_inst_id = instance_number
and prior blocking_session = session_id
and prior blocking_session_serial# = session_serial#
order siblings by dbid, sample_time;
LV ISLEAF ISCYCLE SAMPLE_TIME INSTANCE_NUMBER SESSION_ID SQL_ID EVENT SESSION_STATE BLOCKING_INST_ID BLOCKING_SESSION BLOCKING_SESSION_STATUS
1 0 0 22:04:32.846 1 1259 3ajt2htrmb83y cursor: WAITING 1 537 VALID
2 1 0 22:04:32.846 1 537 3ajt2htrmb83y SGA: WAITING UNKNOWN
select t.lv,
t.iscycle,
t.dbid,
t.sample_id,
t.sample_time,
t.instance_number,
t.session_id,
t.sql_id,
t.session_type,
t.event,
t.seq#,
t.session_state,
t.blocking_inst_id,
t.blocking_session,
t.blocking_session_status,
t.c blocking_session_count
from (select t.*,
row_number() over(partition by dbid, instance_number, sample_time order by c desc) r
from (select t.*,
count(*) over(partition by dbid, instance_number, sample_time, session_id) c,
row_number() over(partition by dbid, instance_number, sample_time, session_id order by 1) r1
from (select
level lv,
connect_by_isleaf isleaf,
connect_by_iscycle iscycle,
t.*
from t_ash t
/*where sample_time >
to_timestamp('2013-11-17 13:55:00',
'yyyy-mm-dd hh24:mi:ss')
and sample_time <
to_timestamp('2013-11-17 14:10:00',
'yyyy-mm-dd hh24:mi:ss')*/
start with blocking_session is not null
connect by nocycle
prior dbid = dbid
and prior sample_time = sample_time
/*and ((prior sample_time) - sample_time between interval '-1'
second and interval '1' second)*/
and prior blocking_inst_id = instance_number
and prior blocking_session = session_id
and prior
blocking_session_serial# = session_serial#) t
where t.isleaf = 1) t
where r1 = 1) t
where r < 3
order by dbid, sample_time, r;
SAMPLE_TIME INSTANCE_NUMBER SESSION_ID SQL_ID EVENT SEQ# SESSION_STATE BLOCKING_SESSION_STATUS BLOCKING_SESSION_COUNT
22:03:32.116 1 1136 1p4vyw2jan43d SGA: 1140 WAITING UNKNOWN 82
22:03:32.116 1 413 9g51p4bt1n7kz SGA: 7646 WAITING UNKNOWN 2
22:03:42.226 1 1136 1p4vyw2jan43d SGA: 1645 WAITING UNKNOWN 154
22:03:42.226 1 537 3ajt2htrmb83y SGA: 48412 WAITING UNKNOWN 4
22:03:52.326 1 1136 1p4vyw2jan43d SGA: 2150 WAITING UNKNOWN 165
22:03:52.326 1 537 3ajt2htrmb83y SGA: 48917 WAITING UNKNOWN 8
22:04:02.446 1 1136 1p4vyw2jan43d SGA: 2656 WAITING UNKNOWN 184
22:04:02.446 1 537 3ajt2htrmb83y SGA: 49423 WAITING UNKNOWN 10
22:04:12.566 1 1136 1p4vyw2jan43d SGA: 3162 WAITING UNKNOWN 187
22:04:12.566 1 2472 SGA: 1421 WAITING UNKNOWN 15
22:04:22.666 1 1136 1p4vyw2jan43d SGA: 3667 WAITING UNKNOWN 193
22:04:22.666 1 2472 SGA: 1926 WAITING UNKNOWN 25
22:04:32.846 1 1136 1p4vyw2jan43d SGA: 4176 WAITING UNKNOWN 196
22:04:32.846 1 2472 SGA: 2434 WAITING UNKNOWN 48
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