Database Reference
In-Depth Information
EVENT
The initialization parameter
EVENT
is partially documented in the
Oracle Database Reference
manual. The parameter syntax as well as which events may be set are undocumented. The manual
states that the parameter must not be used except under the supervision of Oracle Support
Services.
The parameter
EVENT
may be used to set one or more events at instance level. Events set
in this way are enabled for the entire lifetime of an instance. All other approaches for setting
events, such as
DBMS_SYSTEM
, do not cover the entire lifetime of an instance. The parameter is
appropriate for situations where other means for setting events are not feasible or events must
be set right when a process starts. Processing of a technical assistance request by Oracle Support
Services may involve setting certain events. A DBA who is familiar with the parameter
EVENT
is
less dependent on Oracle Support and may find a workaround or gather diagnostic data without
needing to ask for assistance.
Syntax
The events that may be set with the parameter
EVENT
are the same events that can be set by
other means, such as
ALTER
SESSION
,
ALTER
SYSTEM
, and
ORADEBUG
. The commonalities go even
further, since the event specification syntax for the aforementioned methods and the parameter
EVENT
is identical. Multiple events may be set by entering several event specifications separated
by colons. The syntax is:
event='event_specification1[:event_specificationN]*'
Brackets indicate that an element is optional. The asterisk indicates that the preceding
element may be repeated. The syntax for an individual event specification is as follows:
event_number trace name context forever, level event_level
The placeholders
event_number
and
event_level
are both integers. Most event numbers
are in the range 10000 to 10999.
9
On UNIX systems, these events are listed in the file
$ORACLE_
HOME/rdbms/mesg/oraus.msg
along with a description. The supported event level is unspecified
for most of the events in the file, such that it may be necessary to involve Oracle Support to
determine the correct level. The OERR utility may be used to retrieve the description for a
certain event. Following is an example for an event that switches off a cost-based optimizer
(CBO) access path:
$ oerr ora 10196
10196, 00000, "CBO disable index skip scan"
// *Cause:
// *Action:
It is also possible to request a diagnostic dump when an ORA-
nnnnn
error occurs. The
syntax for this is identical to the syntax that must be used with
ALTER
SESSION
/
SYSTEM
SET
EVENTS
(covered in Chapter 13). Further information on events is provided in Part III.
9.
Events 14532 (enable bug fix for excess use of shared pool memory during DDL on partitioned objects
in 10.2.0.3) and 38068 (CBO enable override of guess impact on index choice) are example exceptions
to this rule.
