通过ASH分析Oracle数据库的历史性能问题

bisal的个人杂货铺 2022-08-18

722

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