Oratop is a utility very similar in nature to the ‘top’ unix OS utility.
It provides an almost real-time overview of both RAC as well as single-instance database performance and can be used in combination with top to get a more complete overview of system performance and identify and monitor any activity causing bottlenecks.
Oratop is available as part of the Trace File Analyzer (TFA) Collector package and also can be downloaded via the MOS note 1500864.1.
What information does oratop show us? – a lot!
- Database instance activity like number of user sessions logged in, number of active sessions, SGA/PGA allocation and usage, I/O activity, Flash Recovery Area and TEMP usage
- Top 5 Wait Events – both real-time as well as since instance start
- Top user sessions and processes as well as sessions blocking others. What database events are sessions waiting on as well as latch activity
- Top SQL_IDs and SQL statements, elapsed time, rows returned
- SQL Execution Plan based on SQL_ID
- Tablespace usage information
- AWR Disk Group space usage information
And much more..!
We can launch oratop via the TFA menu interface as shown below :
We can also launch oratop from the command line via tfactl.
/u01/app/126.96.36.199/grid/tfa/aunmmorac1n1/tfa_home/bin/tfactl oratop -database “tppsnm1”
There are a number of switches available in the oratop utility to enable us to toggle the information which is displayed.
Let us have a look at some of them.
By default, oratop will display the Top 5 Wait Events since instance start. To view the information real-time we can use ‘d‘.
The Events are now shown real-time (RT) instead of the default (C).
Use ‘m‘ to toggle between display of Programs and display of Modules.
Use ‘s‘ to toggle between Process Mode (default) and SQL Mode.
Use ‘a‘ for ASM Disk Group information.
Use ‘x‘ to display the SQL Execution Plan for a specific SQL ID.
Use ‘i‘ to change the refresh or data gathering interval.
Use ‘h‘ to display the Help menu. We can view the Help menu for each section individually.