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如何利用ash监控会话
ash是非常有效的监控工具之一，1秒抓一次
select max(sample_time)over(),min(sample_time)over() from dba_hist_active_sess_history; --8天
select max(sample_time)over(),min(sample_time)over() from v$active_session_history; --当天
首先先了解几个视图：
V$ACTIVE_SESSION_HISTORY: 是ASH的核心，用以记录活动SESSION的历史等待信息，每秒采样一次，这部分内容记录在内存中，期望值是记录一个小时的内容。
WRH#_ACTIVE_SESSION_HISTORY : 是V$ACTIVE_SESSION_HISTORY在AWR的存储地。
V$ACTIVE_SESSION_HISTORY: 中的信息会被定期(每小时一次)的刷新到负载库中，并缺省保留一个星期用于分析。
DBA_HIST_ACTIVE_SESS_HISTORY: 视图是WRH#_ACTIVE_SESSION_HISTORY视图和其他几个视图的联合展现，通常通过这个视图进行历史数据的访问。
------------------------------------
--V$ACTIVE_SESSION_HISTORY的监控：--
------------------------------------
------------session：1-----------------
SQL> @big
SID
----------
131
Elapsed: 00:00:00.00
drop table big
*
ERROR at line 1:
ORA-00942: table or view does not exist
Elapsed: 00:00:00.03
Elapsed: 00:00:00.31
Elapsed: 00:00:00.34
Elapsed: 00:00:00.29
Elapsed: 00:00:00.73
Elapsed: 00:00:01.75
Elapsed: 00:00:10.59
Elapsed: 00:00:24.62
Elapsed: 00:00:00.01
BIG_M
----------
522
Elapsed: 00:00:00.36
COUNT(*)
----------
4650368
Elapsed: 00:00:26.70
------------session：2-----------------
SQL> @getash_sid
Enter value for sid: 131
SESSION_ID NAME P_NAME P_VALUE SQL_ID WAIT_TIME CURRENT_OBJ# CURRENT_FILE# CURRENT_BLOCK#
---------- ---------------------------------------------------------------- --------------- --------------- ------------- ---------- ------------ ------------- ---------
131 db file sequential read file# 1 d2wbn28rdk8z4 0 547 1 3604
block# 53206
blocks 1
131 db file sequential read file# 1 d2wbn28rdk8z4 0 -1 0 0
block# 3009
blocks 1
131 db file scattered read file# 4 03b71c07nsc1a 0 134 1 1064
block# 4845
blocks 8
131 log buffer space 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch completion 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 6046
0
0
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 4995
block# 4995
blocks 5
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 7170
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 7170
0
0
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 8578
block# 8578
blocks 126
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 12802
block# 12802
blocks 126
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 12930
0
0
131 db file sequential read file# 1 aq32z6wjx1s4h 0 65921 201 3585
block# 2854
blocks 1
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 14084
block# 14084
blocks 124
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 18436
block# 18436
blocks 128
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 19972
block# 19972
blocks 128
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 21252
block# 21252
blocks 124
131 db file parallel read files 1 aq32z6wjx1s4h 0 76851 4 23424
blocks 29
requests 29
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 24320
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 24320
0
0
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 25856
block# 25856
blocks 128
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 27652
block# 27652
blocks 124
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 29312
block# 29312
blocks 32
131 Disk file operations I/O FileOperation 2 aq32z6wjx1s4h 0 76851 4 29952
fileno 0
filetype 2
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 30724
block# 30724
blocks 124
131 db file scattered read file# 4 aq32z6wjx1s4h 0 76851 4 34530
block# 34530
blocks 14
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 35716
0
0
131 log file switch (checkpoint incomplete) 0 aq32z6wjx1s4h 0 76851 4 35716
0
0
131 Disk file operations I/O FileOperation 5 aq32z6wjx1s4h 0 76851 4 37632
fileno 0
filetype 2
131 db file sequential read file# 4 fqcxb1n33642x 0 9 1 86832
block# 4999
blocks 1
131 db file scattered read file# 4 fqcxb1n33642x 0 9 1 86832
block# 10344
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 9 1 86832
block# 17409
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 9 1 86832
block# 22083
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 9 1 86832
block# 28549
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 9 1 86832
block# 34733
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 9 1 86832
block# 39217
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 9 1 86832
block# 45114
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 9 1 86832
block# 48836
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 9 1 86832
block# 52391
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 5196
block# 5196
blocks 6
131 db file sequential read file# 4 fqcxb1n33642x 0 76851 4 8261
block# 8261
blocks 1
131 db file sequential read file# 4 fqcxb1n33642x 0 76851 4 11318
block# 11318
blocks 1
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 14489
block# 14489
blocks 56
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 17935
block# 17935
blocks 50
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 21195
block# 21195
blocks 20
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 25170
block# 25170
blocks 2
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 28453
block# 28453
blocks 34
131 db file sequential read file# 4 fqcxb1n33642x 0 76851 4 33067
block# 33067
blocks 1
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 36991
block# 36991
blocks 13
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 41616
block# 41616
blocks 21
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 44055
block# 44055
blocks 8
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 2723
block# 2723
blocks 44
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 50056
block# 50056
blocks 9
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 53658
block# 53658
blocks 102
131 db file scattered read file# 4 fqcxb1n33642x 0 76851 4 56580
block# 56580
blocks 128
131 db file sequential read file# 4 fqcxb1n33642x 0 76851 4 60256
block# 60256
blocks 1
64 rows selected.
Elapsed: 00:00:00.40
SQL> @getsql_sqlid
Enter 1 for curr sql, 2 for hist sql,default 1:
Enter value for sqlid: fqcxb1n33642x
SQL_FULLTEXT
---------------------------------------------------------------------------------------------
select count(*) from big
Elapsed: 00:00:00.00
Elapsed: 00:00:00.00
SQL> @getobj_id
Enter value for dblink:
Enter value for obj_id: 76851
OWNER OBJECT_NAME OBJECT_TYPE CREATED STATUS
-------------------- ------------------------------ ------------------- ------------------- -------
SCOTT BIG TABLE 2014-11-20 15:56:23 VALID
1 row selected.
Elapsed: 00:00:00.01
SQL> @getobj_fb
Enter value for file_id: 4
Enter value for block_id: 60256
OWNER SEGMENT_NAME SEGMENT_TY
--------------- -------------------- ----------
SCOTT BIG TABLE
1 row selected.
Elapsed: 00:00:00.37
--------------------------@脚本--------------------
--@big
@sid
set feedback off
drop table big;
create table big as select * from dba_objects;
insert into big select * from big;
/
/
/
/
/
commit;
select SUM(bytes) / 1024 / 1024 big_M from dba_segments where segment_name = 'BIG';
select count(*) from big;
set feedback on
--@getash_sid
col p_name for a15
col p_value for a15
select SESSION_ID,
NAME,
P1TEXT||chr(10)||P2TEXT||chr(10)||P3TEXT p_name,
p1||chr(10)||p2||chr(10)||p3 p_value,
sql_id,
WAIT_TIME,
CURRENT_OBJ#,
CURRENT_FILE#,
CURRENT_BLOCK#
from v$active_session_history ash, v$event_name enm
where ash.event# = enm.event#
and SESSION_ID = &sid
order by sample_time;
----------------------------------------
--DBA_HIST_ACTIVE_SESS_HISTORY的监控：--
----------------------------------------
--查当前时间
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual;
--根据时间找到snap_id（8天内，1小时前），因为基表非常大，利用snap_id的索引才能快速查询
select distinct snap_id from dba_hist_snapshot b where to_date('2014-11-20 14:08:12','yyyy-mm-dd hh24:mi:ss') between b.begin_interval_time and b.end_interval_time;
--top instance
select /*+parallel(a,8)*/instance_number,count(*) from dba_hist_active_sess_history a where a.snap_id=67421 group by instance_number;
--top event
select /*+parallel(a,8)*/event,count(*) from dba_hist_active_sess_history a
where a.snap_id=67421
and instance_number=2
and sample_time>=to_timestamp('2014-11-20 14:07:12','yyyy-mm-dd hh24:mi:ss')
and sample_time<=to_timestamp('2014-11-20 14:08:12','yyyy-mm-dd hh24:mi:ss')
group by event
order by count(*) desc;
--top user
select /*+parallel(a,8)*/user_id,(select username from dba_users b where b.user_id=a.user_id) username,count(*) from dba_hist_active_sess_history a
where a.snap_id=67421
and instance_number=2
and sample_time>=to_timestamp('2014-11-20 14:07:12','yyyy-mm-dd hh24:mi:ss')
and sample_time<=to_timestamp('2014-11-20 14:08:12','yyyy-mm-dd hh24:mi:ss')
group by user_id
order by count(*) desc;
--top sql
select /*+parallel(a,8)*/sql_id,count(*) from dba_hist_active_sess_history a
where a.snap_id=67421
and instance_number=2
and sample_time>=to_timestamp('2014-11-20 14:07:12','yyyy-mm-dd hh24:mi:ss')
and sample_time<=to_timestamp('2014-11-20 14:08:12','yyyy-mm-dd hh24:mi:ss')
group by sql_id
order by count(*) desc;
-- select SQL_TEXT from dba_hist_sqltext where sql_id='49p4hfj6azw19';
--top program
select /*+parallel(a,8)*/program,count(*) from dba_hist_active_sess_history a
where a.snap_id=67421
and instance_number=2
and sample_time>=to_timestamp('2014-11-20 14:07:12','yyyy-mm-dd hh24:mi:ss')
and sample_time<=to_timestamp('2014-11-20 14:08:12','yyyy-mm-dd hh24:mi:ss')
group by program
order by count(*) desc;
如何利用ash监控会话
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