More than often I’m asked to investigate “what happened yesterday when performance problems appeared”.
Sometimes I have the Enterprise Manager DB Console licensed, sometimes not. Sometimes I have direct SQL*Net access to the database that I may use to produce custom reports with my LAMP self-developed application. But it may happen that only an ssh access is granted to the db server.
That’s why I started to develop some little scripts to plot the trends of database timed statistics.
Let’s see this one:
SQL> @sysstat.sql
Enter a sysstat to search for: physical reads
STAT_ID STAT_NAME
----------- ------------------------------------------
2263124246 physical reads
4171507801 physical reads cache
297908839 physical reads cache prefetch
2589616721 physical reads direct
2564935310 physical reads direct (lob)
2663793346 physical reads direct temporary tablespace
473165409 physical reads for flashback new
3102888545 physical reads prefetch warmup
531193461 physical reads retry corrupt
9 rows selected.
Enter the desired stat_id: 2263124246
Enter the start date (YYYYMMDD) [defaults today] : 20080922
Enter the end date date (YYYYMMDD) [defaults today] : 20080922
STAT_NAME START END
---------------- -------- --------
physical reads 20080922 20080922
BEGIN_INTERVAL_TIME VALORE PLOTTED_VALUE
------------------------- ---------- -------------------------
22-SEP-08 12.00.12.122 AM 0
22-SEP-08 01.00.28.253 AM 120092
22-SEP-08 02.00.05.039 AM 35780
22-SEP-08 03.00.55.595 AM 4792
22-SEP-08 04.00.43.725 AM 4905
22-SEP-08 05.00.31.855 AM 7300
22-SEP-08 06.00.17.017 AM 234596
22-SEP-08 07.00.08.132 AM 24651
22-SEP-08 08.00.50.936 AM 481884
22-SEP-08 09.00.33.488 AM 130201
22-SEP-08 10.00.03.805 AM 1300306 **
22-SEP-08 11.00.07.764 AM 491857
22-SEP-08 12.00.31.548 PM 304702
22-SEP-08 01.01.04.880 PM 1023664 *
22-SEP-08 02.00.17.822 PM 8588180 ************
22-SEP-08 03.00.36.969 PM 2201615 ***
22-SEP-08 04.01.01.397 PM 17237098 *************************
22-SEP-08 05.00.39.262 PM 1606300 **
22-SEP-08 06.00.03.829 PM 451568
22-SEP-08 07.00.31.461 PM 137684
22-SEP-08 08.00.05.966 PM 203803
22-SEP-08 09.00.24.829 PM 536394
22-SEP-08 10.00.12.945 PM 10209783 **************
22-SEP-08 11.00.35.123 PM 6151663 *********
24 rows selected.
Oh! At 4.00 PM we had a lot of physical reads. Nice.
This is the code:
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-- display given statistics from DBA_HIST_SYSSTAT col BEGIN_INTERVAL_TIME for a25 set pages 100 lines 130 set verify off term on accept sysstat prompt 'Enter a sysstat to search for: ' select STAT_ID, STAT_NAME from DBA_HIST_STAT_NAME where lower(STAT_NAME) like lower('%&sysstat%') order by stat_name; accept stat_id prompt 'Enter the desired stat_id: ' accept startdate prompt 'Start date (YYYYMMDD) [today] : ' accept enddate prompt 'End date date (YYYYMMDD) [today] : ' select STAT_NAME, nvl('&startdate',to_char(sysdate,'YYYYMMDD')) as "START", nvl('&enddate',to_char(sysdate,'YYYYMMDD')) as "END" from DBA_HIST_STAT_NAME where STAT_ID = &stat_id; select BEGIN_INTERVAL_TIME, VALORE, substr( rpad('*',40*round( VALORE/max(VALORE)over(),2),'*'),1,40) PLOTTED_VALORE from ( select s.BEGIN_INTERVAL_TIME BEGIN_INTERVAL_TIME, nvl(decode(greatest(VALUE, nvl(lag(VALUE) over (partition by s.dbid, s.instance_number, g.stat_name order by s.snap_id),0)), VALUE, VALUE - lag(VALUE) over (partition by s.dbid, s.instance_number, g.stat_name order by s.snap_id),VALUE), 0) VALORE from DBA_HIST_SNAPSHOT s, DBA_HIST_SYSSTAT g, v$instance i where s.SNAP_ID=g.SNAP_ID and g.STAT_ID='&stat_id' and s.BEGIN_INTERVAL_TIME >= trunc(to_timestamp(nvl('&startdate',to_char(sysdate,'YYYYMMDD')),'YYYYMMDD')) and s.BEGIN_INTERVAL_TIME < = trunc(to_timestamp(nvl('&enddate',to_char(sysdate,'YYYYMMDD')),'YYYYMMDD')+1) and s.instance_number=i.instance_number and s.instance_number=g.instance_number order by 1 ); |
Ciao
—
Ludovico