标签：tab count number session sysdate ddr blocking over 执行计划
===================================================== 数据库异常处理 ======================================================================
一、当前情况
1、监控当前TOPAS
topas
2、监控当前等待事件
set pagesize 999
set linesize 300
col event format a66
col wait_class format a30
select event,count(*),wait_class from gv$session group by event,wait_class order by 2;
3、通过等待事件检查会话
col machine format a32
col event format a32
col program format a32
set linesize 555
select sid,machine,program,sql_id,event,p1,p2 from v$session where event=‘&event_list‘ order by sql_id;
4、监控当前的数据库会话信息
set pagesize 999
set lines 666
col username format a13
col prog format a10 trunc
col sql_text format a41 trunc
col sid format 999999
col child for 999999
col avg_etime for 999,999,.99
col EXECS for 99999999999
select sid,
serial#,
status,
username,
substr(program,1,19) prog,
address,
hash_value,
b.sql_id,
child_number child,
plan_hash_value,
executions execs,
(elapsed_time / decode(nvl(executions,0),0,1,executions)) / 1000000 avg_etime,
sql_text
from v$session a,v$sql b
where status=‘ACTIVE‘
and username is not null
and a.sql_id=b.sql_id
and a.sql_child_number=b.child_number
and sql_text not like
‘%select sid,serial#,username,substr(program,1,19) prog,%‘ --don‘t show this query
order by sql_id,sql_child_number
/
5、根据以上查询的检查异常SQL_ID，主要检查 PLAN_HASH_VALUE
set lines 155
col execs for 999,999,999
col avg_etime for 999,999.999
col avg_lio for 999,999,999.9
col begin_interval_time for a30
col node for 99999
break on plan_hash_value on startup_time skip 1
select ss.snap_id,
ss.instance_number node,
begin_interval_time,
sql_id,
plan_hash_value,
nvl(executions_delta,0) execs,
(elapsed_time_delta /
decode(nvl(executions_delta,0),0,1,executions_delta))/1000000 avg_etime,
(buffer_gets_delta /
decode(nvl(buffer_gets_delta,0),0,1,executions_delta)) avg_lio,
(disk_reads_delta/
decode(nvl(buffer_gets_delta,0),0,1,executions_delta)) avg_pio
from DBA_HIST_SQLSTAT S,DBA_HIST_SNAPSHOT SS
where sql_id=‘&sql_id‘
and ss.snap_id=S.snap_id
and ss.instance_number=S.instance_number
and s.instance_number like nvl(‘&instance_number‘,s.instance_number)
and executions_delta>0
order by 1,2,3
/
6、通过上面的返回查看执行计划是否改变，检查执行计划
set linesize 300
select * from table(DBMS_XPLAN.DISPLAY_CURSOR(to_char(‘&sql_id‘),NULL));
二、非当前情况
1、检查快照信息
select INSTANCE_NUMBER,SNAP_ID,BEGIN_INTERVAL_TIME from DBA_HIST_SNAPSHOT where BEGIN_INTERVAL_TIME>sysdate-1 order by SNAP_ID;
##语句在时间段内的消耗情况（snap_id）
select /*+parallel(t,4)*/
plan_hash_value,
buffer_gets_delta/executions_delta get_exec,
disk_reads_delta/executions_delta read_exec,
cpu_time_delta/executions_delta/1000 cpu_exec_ms ,
elapsed_time_delta/executions_delta/1000 elaps_exec_ms ,
parsing_schema_id,
ROWS_PROCESSED_delta/executions_delta rows_exec,
executions_delta
from dba_hist_sqlstat t
where sql_id = ‘1mgfnuxggrfj0‘
and instance_number = 1
and SNAP_ID between 8978 and 8988
and EXECUTIONS_DELTA > 0;
回放故障期间数据库层等待事件的情况：
col event for a35
set lines 222
set pages 9999
col p1 for 999999999999999999999999999999
select instance_number,sample_id,sample_time,event,count(*) from dba_hist_active_sess_history
where sample_time >
to_timestamp(‘2018-08-02 11:00:00‘,‘yyyy-mm-dd hh24:mi:ss‘)
and sample_time <
to_timestamp(‘2018-08-02 11:55:00‘,‘yyyy-mm-dd hh24:mi:ss‘)
--and event =‘change tracking file synchronous read‘
group by instance_number,sample_id,sample_time,event
order by 1,3,5;
col event for a35
set lines 222
set pages 9999
col p1 for 999999999999999999999999999999
select sample_id,sample_time,event,count(*) from gv$active_session_history;
where INST_ID=2 and event is not null
and sample_id between 43715229 and 43715911
group by sample_id,sample_time,event
order by 1,4;
2、按照快照检查SQL执行信息
set lines 155
col execs for 999,999,999
col min_etime for 999,999.99
col max_etime for 999,999.99
col avg_etime for 999,999.999
col avg_lio for 999,999,999.9
col norm_stddev for 999,999.9999
col begin_interval_time for a30
col node for 99999
break on plan_hash_value on startup_time skip 1
select * from
(select sql_id,
sum(execs),
min(avg_etime) min_etime,
max(avg_etime) max_etime,
stddev_etime / min(avg_etime) norm_stddev
from (select sql_id,
plan_hash_value,
execs,
avg_etime,
stddev(avg_etime) over(partition by sql_id) stddev_etime
from (select sql_id,
plan_hash_value,
sum(nvl(executions_delta,0)) execs,
(sum(executions_delta)/
decode(sum(nvl(executions_delta,0)),
0,
1,
sum(executions_delta)) /1000000) avg_etime
--,sum((buffer_gets_delta/decode(nvl(buffer_gets_delta,0),0,1,executions_delta)) avg_lio
from DBA_HIST_SQLSTAT S,DBA_HIST_SNAPSHOT SS
where ss.snap_id=s.snap_id
and ss.instance_number=s.instance_number
and executions_delta>0
and elapsed_time_delta>0
and s.snap_id > nvl(‘&start_snap_id‘,0)
and s.snap_id < nvl(‘&last_snap_id‘,0)
group by sql_id,plan_hash_value))
group by sql_id,stddev_etime)
where max_etime>0.01
order by 4
/
3、根据时间检查SQL的信息 （可以修改default的值 当前为0.5天）
alter session set nls_date_format=‘yyyy-mm-dd hh24:mi:ss‘;
accept days_ago -
prompt ‘Enter Days ago: ‘ -
default ‘1‘
set lines 155
col execs for 999,999,999
col before_etime for 999,990.99
col after_etime for 999,990.99
col before_avg_etime for 999,990.99 head AVG_ETIME_BEFORE
col after_avg_etime for 999,990.99 head AVG_ETIME_AFTER
col min_etime for 999,990.99
col max_etime for 999,990.99
col avg_etime for 999,990.999
col avg_lio for 999,999,990.9
col norm_stddev for 999,990.9999
col begin_interval_time for a30
col node for 99999
break on plan_hash_value on startup_time skip 1
select * from (
select sql_id, execs, before_avg_etime, after_avg_etime, norm_stddev,
case when to_number(before_avg_etime) < to_number(after_avg_etime) then ‘Slower‘ else ‘Faster‘ end result
-- select *
from (
select sql_id, sum(execs) execs, sum(before_execs) before_execs, sum(after_execs) after_execs,
sum(before_avg_etime) before_avg_etime, sum(after_avg_etime) after_avg_etime,
min(avg_etime) min_etime, max(avg_etime) max_etime, stddev_etime/min(avg_etime) norm_stddev,
case when sum(before_avg_etime) > sum(after_avg_etime) then ‘Slower‘ else ‘Faster‘ end better_or_worse
from (
select sql_id,
period_flag,
execs,
avg_etime,
stddev_etime,
case when period_flag = ‘Before‘ then execs else 0 end before_execs,
case when period_flag = ‘Before‘ then avg_etime else 0 end before_avg_etime,
case when period_flag = ‘After‘ then execs else 0 end after_execs,
case when period_flag = ‘After‘ then avg_etime else 0 end after_avg_etime
from (
select sql_id, period_flag, execs, avg_etime,
stddev(avg_etime) over (partition by sql_id) stddev_etime
from (
select sql_id, period_flag, sum(execs) execs, sum(etime)/sum(decode(execs,0,1,execs)) avg_etime from (
select sql_id, ‘Before‘ period_flag,
nvl(executions_delta,0) execs,
(elapsed_time_delta)/1000000 etime
-- sum((buffer_gets_delta/decode(nvl(buffer_gets_delta,0),0,1,executions_delta))) avg_lio
from DBA_HIST_SQLSTAT S, DBA_HIST_SNAPSHOT SS
where ss.snap_id = S.snap_id
and ss.instance_number = S.instance_number
and executions_delta > 0
and elapsed_time_delta > 0
and ss.begin_interval_time <= sysdate-&&days_ago
union
select sql_id, ‘After‘ period_flag,
nvl(executions_delta,0) execs,
(elapsed_time_delta)/1000000 etime
-- (elapsed_time_delta)/decode(nvl(executions_delta,0),0,1,executions_delta)/1000000 avg_etime
-- sum((buffer_gets_delta/decode(nvl(buffer_gets_delta,0),0,1,executions_delta))) avg_lio
from DBA_HIST_SQLSTAT S, DBA_HIST_SNAPSHOT SS
where ss.snap_id = S.snap_id
and ss.instance_number = S.instance_number
and executions_delta > 0
and elapsed_time_delta > 0
and ss.begin_interval_time > sysdate-&&days_ago
-- and s.snap_id > 7113
)
group by sql_id, period_flag
)
)
)
group by sql_id, stddev_etime
)
)
where after_avg_etime>0.01
order by norm_stddev
/
4、根据以上查询的检查异常SQL_ID，主要检查PLAN_HASH_VALUE
set lines 155
col execs for 999,999,999
col avg_etime for 999,999.999
col avg_lio for 999,999,999.9
col begin_interval_time for a30
col node for 99999
break on plan_hash_value on startup_time skip 1
select ss.snap_id,
ss.instance_number node,
begin_interval_time,
sql_id,
plan_hash_value,
nvl(executions_delta,0) execs,
(elapsed_time_delta/
decode(nvl(executions_delta,0),0,1,executions_delta))/1000000 avg_etime,
(buffer_get_delta/
decode(nvl(buffer_gets_delta,0),0,1,executions_delta)) avg_lio,
(disk_reads_delta/
decode(nvl(buffer_gets_delta,0),0,1,executions_delta)) avg_pio
from DBA_HIST_SQLSTAT S,DBA_HIST_SNAPSHOT SS
where sql_id-‘&sql_id‘
and ss.snap_id=s.snap_id
and ss.instance_number=s.instance_number
and s.instance_number like ‘&instance_number‘
and executions_delta > 0
order by 1,2,3
/
5、通过上面的返回查看执行计划是否改变，检查执行计划
set pagesize 999
set linesize 380
select * from table(dbms_xplan.display_cursor(to_char(‘&sql_id‘),NULL);
6、根据快照ID查询SQL_ID的来源信息（查所有的视图太大）
set linesize 555
set pagesize 999
col event format a40
col program format a30
col wait_class format a20
select snap_id,instance_number,session_id,sql_id,event,wait_class,p1,p2,p3,blocking_session,blocking_inst_id,program
from dba_hist_active_sess_history
where snap_id > &start_snap_id
and snap_id < &last_snap_id
and sql_id = &sql_id
order by snap_id,program;
标签：tab count number session sysdate ddr blocking over 执行计划
原文地址：https://www.cnblogs.com/dc-chen/p/12954724.html
