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Re: Oracle Key Concepts - Make Sure You Know All!

From: <>
Date: Fri, 14 Sep 2007 08:15:11 -0700
Message-ID: <>

On Sep 14, 6:08 am, "" <> wrote:
> Oracle Key Concepts - Make Sure You Know All!
> Oracle Key Concepts - Make sure you know all especially before
> appearing for Oracle Certification (i.e. to becoming Oracle Certified
> Professional or OCP)

Some of Asim Abbasi's key concepts ...

3. Oracle Database is encrypted and we cannot read it through any Text Editor like MS Word.

Wrong. It's not encrypted at all as I can output a good portion of the file with the strings command. I wouldn't want to open it with Notepad or vi, but a good bit of it would be readable. And Microsoft Word is NOT a text editor.

7. Following analogies help you in building concept

  1. Instance = Genie
  2. Database = Notebook
  3. Session = Aladdin (or connected Users)

I haven't seen questions on Aladdin on any OCP exams, nor have I experienced any interrogatories involving Genies. I'm wondering what's in your medicine chest,

  1. Steps to Master Oracle
  2. SQL
  3. DBA
  4. Network Admin
  5. Bkup & Recov.
  6. Performance Tuning

So if I can correctly write 'select * from dual;' I'm qualified to move on to database administration? And I don't need to bother with backup and recovery and networking before I become a DBA? You need to think again, Asim.

22. Data inside the segment can reside in two or more data files with the same tablespace.

No. A single segment does not cross file boundaries. The segments for a given object can span multiple data files, but a single segment, and the data within, resides in ONE datafile.

29. A database should have at least two Redo Log groups.

A small niggle here, but 'should' isn't the proper word here. A database MUST have at least two Redo log groups. Period.

35. Human brain works pretty much the same way Oracle Instance works.

Really? So amnesia is caused by too many ORA-01555 errors? Or would that be too many ORA-00942 errors?

76. Primary/Foreign key relationship needs not to be present among tables for making SELECT statement containing "joins" to run. 78. Primary & Foreign Key has nothing to do with Joins statements.

Which is it, Asim? Did you mean to say that a join operates on tables containing related data? Simply because two tables contain related data (EMP and DEPT, for example) in no way ensures or implies a primary key/foreign key relationship exists. Creating the demo tables in Oracle creates no such relationship between EMP and DEPT, yet the tables contain related data and a join between them using the proper column successfully returns data from both entities.

87. DBA is the owner of all the schemas and hence all the objects within each of these schemas.

Hmmm, then why can't a DBA, by default, grant object privileges from one schema owner to another? GRANT SELECT on BOB.MYTABLE to ED; fails if the DBA isn't BOB and this DBA hasn't been explicitly granted SELECT with ADMIN OPTION on BOB.MYTABLE. And, by default, a DBA account isn't granted such wide-ranging privileges.

90. Each value in the Primary Key column is a unique identifier for the whole record/row or in other words, no duplicate or NULL values are allowed in Primary key constraint column.

You assume the primary key is a single column, and it may not be, thus your uniqueness within that column doesn't exist, as it's the uniqueness of the ENTIRE KEY which determines what is or is not a duplicate.

  1. spfile has made possible the ALTER SYSTEM statement to get utilized in changing any initialization parameter with no need to restart the Oracle Server.

Wrong. Some parameters cannot be changed in a running instance, spfile or not. You CAN change the value in the spfile then stop and restart the instance to effect such changes.

There are more of these 'gems' but I think you get the idea. I'd hate to see an OCP with this knowledge base interview for a job.

David Fitzjarrell Received on Fri Sep 14 2007 - 10:15:11 CDT

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