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Determining transactions per second

This code can approximate the number of transactions per second by looking at the number of SCN changes per second.

When asked how many transactions per second were happening on each system, I realized that a quick approximation could be derived from the number of SCN changes per second as recorded in the logs, so I wrote the following code.

Management asked for a rough cut on the number of transactions per second because that's how vendors describe their systems. We were looking to replace our systems with newer, larger machines. Rather than just calculate an overall average, I realized that determining utilization by hour would let us identify peak loads so that the new machine could be sized to handle the peaks and not just the daily average. Subsequently, we use it to monitor system utilization: We watch for changes in the level of system utilization and can tell if an user performance concern is due to increased system load.

I've run it on Oracle 8 & 9. It does not work on 7.

set pages 60
set lines 132
set term off
ttitle off
column dbname  new_value  dbname
column time_stamp new_value time_stamp
column timestamp_np noprint
column year_np noprint
column month_np noprint
column mon format a3
column day   format a2
set verify off
select name dbname, substr(to_char(sysdate,'YYYY-Mon-DD HH24:MI:SS'),1,20)
   from v$database;
ttitle left "Transactions (SCNs) per second" center "&dbname" right
set term on
column tps00 format 999 head "00"
column tps01 format 999 head "01"
column tps02 format 999 head "02"
column tps03 format 999 head "03"
column tps04 format 999 head "04"
column tps05 format 999 head "05"
column tps06 format 999 head "06"
column tps07 format 999 head "07"
column tps08 format 999 head "08"
column tps09 format 999 head "09"
column tps10 format 999 head "10"
column tps11 format 999 head "11"
column tps12 format 999 head "12"
column tps13 format 999 head "13"
column tps14 format 999 head "14"
column tps15 format 999 head "15"
column tps16 format 999 head "16"
column tps17 format 999 head "17"
column tps18 format 999 head "18"
column tps19 format 999 head "19"
column tps20 format 999 head "20"
column tps21 format 999 head "21"
column tps22 format 999 head "22"
column tps23 format 999 head "23"
select * from
select substr(year_np,1,8)  timestamp_np,
       substr(year_np,5,2) Mon, substr(year_np,7,2) Day,
       sum(decode(substr(year_np,9,2),'00',1,0) * tps)   tps00,
       sum(decode(substr(year_np,9,2),'01',1,0) * tps)   tps01,
       sum(decode(substr(year_np,9,3),'02',1,0) * tps)   tps02,
       sum(decode(substr(year_np,9,2),'03',1,0) * tps)   tps03,
       sum(decode(substr(year_np,9,2),'04',1,0) * tps)   tps04,
       sum(decode(substr(year_np,9,3),'05',1,0) * tps)   tps05,
       sum(decode(substr(year_np,9,2),'06',1,0) * tps)   tps06,
       sum(decode(substr(year_np,9,2),'07',1,0) * tps)   tps07,
       sum(decode(substr(year_np,9,3),'08',1,0) * tps)   tps08,
       sum(decode(substr(year_np,9,2),'09',1,0) * tps)   tps09,
       sum(decode(substr(year_np,9,2),'11',1,0) * tps)   tps10,
       sum(decode(substr(year_np,9,3),'11',1,0) * tps)   tps11,
       sum(decode(substr(year_np,9,3),'12',1,0) * tps)   tps12,
       sum(decode(substr(year_np,9,2),'13',1,0) * tps)   tps13,
       sum(decode(substr(year_np,9,2),'14',1,0) * tps)   tps14,
       sum(decode(substr(year_np,9,3),'15',1,0) * tps)   tps15,
       sum(decode(substr(year_np,9,2),'16',1,0) * tps)   tps16,
       sum(decode(substr(year_np,9,2),'17',1,0) * tps)   tps17,
       sum(decode(substr(year_np,9,3),'18',1,0) * tps)   tps18,
       sum(decode(substr(year_np,9,2),'19',1,0) * tps)   tps19,
       sum(decode(substr(year_np,9,2),'20',1,0) * tps)   tps20,
       sum(decode(substr(year_np,9,3),'21',1,0) * tps)   tps21,
       sum(decode(substr(year_np,9,3),'22',1,0) * tps)   tps22,
       sum(decode(substr(year_np,9,2),'23',1,0) * tps)   tps23
  from (select to_char(first_time,'YYYYMMDDHH24') year_np,
               (max(next_change#) - min(first_change#))/(60 * 60) tps
          from v$log_history
         group by to_char(first_time,'YYYYMMDDHH24')
group by substr(year_np,1,8), substr(year_np,5,2), substr(year_np,7,2)
order by timestamp_np

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