Monday, June 25, 2007

Getting a job as a Junior DBA - series

Unfortunately, due to some unspecified events happened early 2008, Howard decide to withdraw his contribution to Oracle community. More info here
The interview series link is no longer valid. I wish I had cut/pasted it :(

One of the most common Q I saw new DBA ask in Oracle forum is what kind of questions employer will ask during a job interview? I tried to sum a few questions I have been asked during job interviews as a job candidate.

Howard Rogers has nice serie in his blog from interviewer's prospective.
Getting a job as a Junior DBA

Frankly if you ask me, I don't want to work for him :) However that doesn't change the fact it's a nice reading.

Heterogeneous Distributed Database Systems

How to maintain a regular data replication between other type of databases with Oracle is a pretty frequently asked question in DBA world.

Consider setup Heterogeneous Distributed Database Systems to solve the problem.

John Palinski has a good post about it here

Saturday, June 23, 2007

Shared Pool Structures

A useful link to a white page about shared pool

Understanding Shared Pool Memory Structures

Also to toubleshoot any ORA-4031 error, metalink has a good note,

Troubleshooting and Diagnosing ORA-4031 Error (previously FAQ: ORA-4031):

Thursday, June 21, 2007

Find out Rollback Segment with active transactions

Use this script to find out how many active transactions link with a rollback segment.


Secure your Password

You should run following script $ORACLE_HOME/rdbms/admin/utlpwdmg.sql
to secure your Password via Default Profile after DB creation. Or expect to see a lot of Policy Violations in your EM dbconsole for the instance.
I don't know why Oracle didn't make these setting 'Default' in the first place.
You could modify the CREATE FUNCTION verify_function part to fit your need.

alter profile default
limit failed_login_attempts 3
password_grace_time 10
password_life_time 45
password_lock_time unlimited
password_reuse_max 180
password_reuse_time unlimited password_verify_function VERIFY_FUNCTION;

Wednesday, June 13, 2007

Quick steps to fix OMS agent problem

Some time when communication between OMS agent and OMS server is interrupted. You have problem to sync up the connection. Common problem/error include,

EMD upload error: uploadXMLFiles skipped :: OMS version not checked yet..

when run
emctl upload

emctl status agent

you will get following lines in result,

Last attempted heartbeat to OMS : 2007-06-07 17:12:30
Last successful heartbeat to OMS : unknown

The quick way to clear the problem is going through following steps:
  1. emctl stop agent
  2. delete all files in $AGENT_HOME/sysman/emd/upload and AGENT_HOME/sysman/emd/state
  3. emctl clearstate agent
  4. emctl secure agent
  5. emctl start agent