Oracle 10g is stealing my processor at 10pm

Question

Hi All,
I have a real time application running on the same server as Oracle 10g. I dont use the database during real time operation, only for persistant store of config data.
At 10pm each night an Oracle process is consuming all CPU on one of the processors for a minute or so, and this is damaging my real time response times.
Can anyone tell me what Oracle is doing here, how do I control it?
Any help appreciated.
Regards,
Keith

Answer 1

The AWR has been described (by Tom Kyte, I believe) as Statspack on steroids. AWR collects database statistics every 60 minutes out of the box (this is configurable), and this data is maintained for a week and then purged. The statistics collected by AWR are stored in the database. To properly collect database statistics, the parameter statistics_level should be set to TYPICAL (the default) or ALL.
The Oracle database uses AWR for problem detection and analysis as well as for self-tuning. A number of different statistics are collected by the AWR including wait events, time model statistics, active session history statistics, various system and session-level statistics, object usage statistics, and information on the most resource-intensive SQL statements. Other Oracle Database 10g features use the AWR, including ADDM and the other advisors in Oracle Database 10g that we will discuss in this series of articles.
If you want to explore the AWR repository, feel free to do so. The AWR consists of a number of tables owned by the SYS schema and typically stored in the SYSAUX tablespace (currently no method exists to move these objects to another tablespace). All AWR table names start with the identifier “WR.” Following WR is a mnemonic that identifies the type designation of the table followed by a dollar sign ($). AWR tables come with three different type designations:
Metadata (WRM$)
Historical data (WRH$)
AWR tables related to advisor functions (WRI$)
Most of the AWR table names are pretty self-explanatory, such as WRM$_SNAPSHOT or WRH$_ACTIVE_SESSION_HISTORY.
Also Oracle Database 10g offers several DBA tables that allow you to query the AWR repository. The tables all start with DBA_HIST, followed by a name that describes the table. These include tables such as DBA_HIST_FILESTATS, DBA_HIST_DATAFILE, or DBA_HIST_SNAPSHOT.