Some Questions about Oracle 10g

[cmptrnerd9]

I am studying for the Oracle 10g OCA exam and I have a few questions on what I have read so far.

1. What exactly do tablespaces do? I come from a SQL Server 2000 background, and I don't think there is anything remotely like tablespaces in SQL Server 2000.

2. I understand what a temporary tablespace is really used for, but I am unsure about why you would want to create more than one of them? Can anyone shed some light on this for me?

3. Does Flash Recovery automatically do log archiving, or do you also have to enable log archiving when setting up the backup and recovery settings in the DBCA?

4. What is the difference between a shared and dedicated server?

5. Can the same user account in Linux/Unix own multiple database objects, or do you have to create a user account for each database?

6. I came across a create database script in the book and it has the line "CONTROLFILE REUSE". Why would you want to reuse a control file? My understanding that it has important information about a specific database??

I appreciate any answers to my questions.

Thanks,
Michael

 

[alexhu]

You need the concepts manual from here

http://tahiti.oracle.com/

Alex

 

[markrem]

You hopefully know these things by now, but just in case you are still working on them ...

1. an Oracle tablespace is similar to a SQL Server file group. However, it is also used to establish default values for tables and indexes. When you create an object and do not specify certain attributes, Oracle uses the default value set at the tablespace level.

2. answer by way of question ... if you take the one and only temp tablespace off line, which temp tablespace will people use? You should create a temp tablespace group that has two or three temp tablespaces in it, and make the group your database's default temp tablespace.

3. the database must be in archivelog mode. In Oracle 9i and earlier, you must also enable archiving using the inti.ora parameter log_archive_start, which is gone in 10g.

4. think about a restaurant. do you want a dedicated waiter or do you want to share your waiter with other tables. Generally, a restaurant cannot afford to hire enough waiters to dedicate one per customer. Generally, if you have over 250 concurrent users you should be using Oracle Shared Servers. However, SYSDBA connections always require a dedicated connection.

5. yes, the same user account can own multiple databases.

6. CONTROLFILE REUSE does not reuse a controlfile. It reuses the file's space on disk, and completely overwrites the old file. If the old file was larger than the new one, Oracle releases the blocks back to the operating system.

I hope that was helpful.

-Mark
9i OCP