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Tracing Sessions: Single SQL_ID, Single Process, New 11g Event Syntax

Happy Reading!!!

Hope you already aware of tracing sessions with different methods

11g onwards, you can trace a session (other session) with in the alter system command itself , no worries of finding pid etc etc. for example like below

SQL> alter session set events ‘sql_trace {process : pid = <pid>, pname = <pname>, […]

Quiz Post #4: Purge single sql from Shared Pool?


How to purge a single statement from shared pool?

Additional info. (Thanks to my friend colleague for updating about the version its possible and the event)

For 10g.

The enhanced DBMS_SHARED_POOL package with the PURGE procedure is included in the patchset release. and customers can download and install RDBMS patch […]

Quiz Post #3: Which background daemon writes to OCR Disk, crsd or cssd?


Which background daemon writes to OCR disk? or the voting disk?

CRSD? Answer No

CRSD just read the OCR to know about its resources.

Its OCSSD under the following conditions , Oracle cluster synchronization service daemon (OCSSD) is responsible for Writing to OCR registry.

a. New Node Addition /Deletion

b. New Service Addition / […]

Performance Tuning Basics: Oracle Common Wait events


Just an excerpt from the Documentation/Note as a ready reference who reads this post.

Oracle Wait events can be divided into two categories , that is idle (IDLE) to wait for events and non-idle (NON-IDLE) .

1) Idle wait event represents ORACLE is waiting on some work at the time of diagnosis […]

PROC-26: Error while accessing the physical storage, PROT-602: ,OCR/Voting Disk fail to mount, OCR corruption

Issue: CRSD not coming up, the other resource until CRS, (need CRS startup sequence, see here) CRSD is failing with error, Possible OCR corruption.

in $GI_HOME/log/<nodename>crsd.log

PROC-26: Error while accessing the physical storage,


GI Version:, RDBMS Version: , Two Node RAC on Linux

We are not using ASMLIB, using block devices directly […]

Quiz Post #2: Why you need to increase the cache size for sys.audsess$ sequence in RAC


Why you need to increase the cache size of sys.audsess$ sequence in RAC?


Background:- In oracle database every session must have an AUDSID (v$session.audsid) when the session spawns/created in database, this number is derived from a sequence called sys.audsess$ where the cache option set to 20 and noorder.

When you have an database […]

11gR2 RAC: Important Trace Directories & Log Locations


Please find the structured 11gR2 GI Clusterware log locations and its relevancy.

Directory structured (Source: Oracle Documentation)

Log Locations


Replication: does Streams works after role transition i.e switchover or failover


Today I have got a call containing couple of questions on streams replication in a standby environment especially when the streams is on downstream capture database.

Here are the questions & my answers to it.


Primary or Source: -10GR2 RAC with 2 node

Standby: Physical Standby

Streams: Downstreams capture database in different server


11g Grid Infrastructure (RAC): CRS Startup Sequence


This is about to understand the startup sequence of Grid Infrastructure daemons and its resources in 11gR2 RAC.


In 11g RAC aka Grid Infrastructure we all know there are additional background daemons and agents, and the Oracle documentation is not so clear nor the other blog.


For example:- I have found below […]

11g Feature: Audit Trail Purging, No more custom scripts

Dear All,

Prior to 11g, in order to purge the audit trails we have to write a custom script and run in a cron or control M scheduler job or a DBMS_SCHEDULER, where in

From 11g onwards Oracle provides a package DBMS_AUDIT_MGMT to manage the audit trails.

Additionally, This package can also be […]