This parameter specifies the interval (in seconds) at which Oracle collects operating statistics. Statistics are only collected when a request is made from the client to the server, or when a request completes.
| Version | Type | Default | Session Modifiable |
System Modifiable |
| 8.0.4 | Integer | 0 | Yes | Immediate |
| 8.0.5 | Integer | 0 | Yes | Immediate |
| 8.0.6 | Integer | 0 | Yes | Immediate |
| 8.1.5 | Integer | 0 | Yes | Immediate |
| 8.1.6 | Integer | 0 | Yes | Immediate |
| 8.1.7 | Integer | 0 | Yes | Immediate |
| 9.0.1 | Integer | 0 | Yes | Immediate |
| 9.2.0 | Integer | 0 | Yes | Immediate |
When TIMED_OS_STATISTICS is enabled statistics are collected as follows:
The default value of zero specifies that operating system statistics are not gathered.
On older systems gathering operating system statistics was very expensive and Oracle recommended:
The parameter can be set in the initialisation file e.g.
timed_os_statistics = 30
This parameter can be set at system level e.g.
ALTER SYSTEM SET timed_os_statistics = 30
This parameter can be set at session level e.g.
ALTER SESSION SET timed_os_statistics = 0
This parameter is apparently not supported on Windows NT or Windows 2000.
Operating system (OS) statistics belong to statistics class 16 (see V$STATNAME.CLASS)
In Oracle 8.0.4 and above the value of TIMED_OS_STATISTICS is the number of seconds
In Oracle 7.3.4 and below, TIMED_OS_STATISTICS can take one of the following values
| Value | Description |
| OFF | Do not gather operating system statistics. This is the default value |
| CALL | Gather statistics at every push or pop call. This option has significant overhead |
| LOGOFF | Gather statistics when the user logs off from an Oracle session |
Statistics affected by enabling TIMED_OS_STATISTICS include:
| OS User level CPU time |
| OS System call CPU time |
| OS Other system trap CPU time |
| OS Text page fault sleep time |
| OS Data page fault sleep time |
| OS Kernel page fault sleep time |
| OS User lock wait sleep time |
| OS All other sleep time |
| OS Wait-cpu (latency) time |
| OS Minor page faults |
| OS Major page faults |
| OS Swaps |
| OS Input blocks |
| OS Output blocks |
| OS Messages sent |
| OS Messages received |
| OS Signals received |
| OS Voluntary context switches |
| OS Involuntary context switches |
| OS System calls |
| OS Chars read and written |
| OS Process heap size |
| OS Process stack size |
The statistics collected may vary by platform and release. The above table represents statistics collected for Oracle 9.2 on Solaris