Re: ** HELP! a couple of "expert" questions **

bpuett_at_interpath.com (Brad Puett) wrote:

>Everone has been so helpful to my questions, so I thought I'd
>take a chance and post these questions which are critical to my
>job ... I've been hired as a consultant, mostly to load data from
>old tables to a new Oracle Database ... But some questions have
>arisen that require DBA skills, and I don't seem to "totally"
>understand how to solve them ... To wit:
>
>1) I KNOW that if you have the ORACLE_SID and ORACLE_HOME
> environment variables set correctly, you can log in and
> do things with SQL*Plus ... I ALSO KNOW that if you have
> the ORACLE_SID, you can find the corresponding ORACLE_HOME
> by looking in the /etc/oratab file ...
>
> What I don't understand is once you have both variables, HOW does
> Oracle determine where your data files are? I mean physically,
> not logically ... What I'm trying to do is prove that I'm working
> with the correct tables in SQL*Plus, but I only know ORACLE_HOME
> and ORACLE_SID ... I need to know which tables are "attached" to
> these 2 variables ... SOMEONE ELSE set up the tables (who is no
> longer with the company) and no one else there knows much about
> Oracle (they've only had it for 6 weeks!)
>
$ORACLE_HOME is the disk/directories that contain the Oracle programs. $ORACLE_SID is used to define the Oracle Instance (database) on the system that you want to access. There can be more than one instance on a given machine.

First, you are not working with the datafiles, only the Oracle instance does that. Oracle knows where it's files are by entries in the control files. The control files are specified by entries in INITsid.ora. Do not try to edit these files Oracle maintains them. The Oracle control files and initialization files normally reside in $ORACLE_HOME/dbs.

To determine which tables you are working with you can select owner,tablename from all_tables. This will show you all tables you have access to and the owner of those tables. I suggest you read the Oracle application developers guide.

>2) What do most people use to back up their data base files? Tar or export?
> I KNOW that you can use TAR to backup everything for the purposes
> of restoring all the data and structures ... suppose you just
>want a cum-
> lative backup, what do you use? Suppose you want to ensure that, once
> you've made changes to the structure of the database (i.e. you have to
> increase the storage size, change some keys in tables, etc.), you can
> restore the data back to the way it was (Note: I don't mean make any
> changes that would preclude putting the data back correctly [adding new
> fields, etc.])
>

If you can shut down oracle before you back up all files then that is the best way to obtain an image of the disks. If the backup has to be done while the database is running, then you will have to take a hot backup and alter the tablespaces begin backup and end backup before and after you back up the data files. You can also export the database to a binary (.dmp) file and then write the .dmp file to tape. That will backup the data in the database but not the database itself. Refer to the Oracle Database Administrators Guide for information on backups.

>3) If you happen to be an "expert" in the software package "Pointman", I have
> some other questions (mostly in how it interacts with the
>database, etc. --
> nothing too technical!)
>

Sorry, never used Pointman.

Dale Fargo, CDP
DBA
Palm Beach County, ISS
dfargo_at_mag.net

>Thanks for any info you can give me!!!
>
>--
>Brad Puett
>bpuett_at_interpath.com
Received on Sun Mar 24 1996 - 00:00:00 CET