Upgrade Experiences from Oracle 7.3.X and Oracle 8.0.X to Oracle 8i

Upgrade Experiences from Oracle 7.3.X and Oracle 8.0.X to Oracle 8i

Post by Douglas Kearne » Sun, 25 Feb 2001 03:17:53



Hi,

     I have scanned the Oracle groups and haven't found much talk about
experiences with upgrading production environments from 7.3.X or 8.0.X to
8i.
I have tried to get on to metalink without much luck because of it being so
slooooow. So, this is the next step. I also noticed that upgrading is
basically taking dumps and re-importing into 8i after server has been
upgraded. Are their any automated steps that I have missed or am I just
crazy?? Wait, I just crazy, this is Oracle we are speaking about. The
platforms that I am interested in are NT,2000, and HP Unix.

Thanks in advance,
Doug K.

 
 
 

Upgrade Experiences from Oracle 7.3.X and Oracle 8.0.X to Oracle 8i

Post by Sybrand Bakke » Sun, 25 Feb 2001 04:39:37




Quote:>Hi,

>     I have scanned the Oracle groups and haven't found much talk about
>experiences with upgrading production environments from 7.3.X or 8.0.X to
>8i.
>I have tried to get on to metalink without much luck because of it being so
>slooooow. So, this is the next step. I also noticed that upgrading is
>basically taking dumps and re-importing into 8i after server has been
>upgraded. Are their any automated steps that I have missed or am I just
>crazy?? Wait, I just crazy, this is Oracle we are speaking about. The
>platforms that I am interested in are NT,2000, and HP Unix.

>Thanks in advance,
>Doug K.

The doc set for Oracle 8 contains a full migration manual. All docs
are online at http://technet.oracle.com (this is a different site from
metalink), so you could prepare for upgrade by scanning through the
migration manual.
The main concern in migration is how your applications deal with the
rowid, as the format of the rowid changes in Oracle 8 (so not in
Oracle 8i). If you use the rowid explicitly (other than Oracle's own
internal rowid mechanisms) you need to take special precautions. In
this scenario you can't use the migration tool (which converts an
existing database in situ, so it upgrades the database), as the
migration tool will not convert the rowids. If you use the export
import route all your rowids are converted automatically. Another
concern with the migration tool you will temporarily have two
dictionaries located in the system tablespace. In the past space
estimates of the migration tool could be wrong, this seems to have
improved. Also, keep in mind using export import reorganizes your
database, which may be benificial in your situation, as you can
address two issues in one go.
The only thing that will strike you probably when you go from 7.3 to
8.0 (so not directly to 8i) is the lack of difference. Some Oracle
instructors call 8.0 '7.4'

Hth

Sybrand Bakker, Oracle DBA

 
 
 

Upgrade Experiences from Oracle 7.3.X and Oracle 8.0.X to Oracle 8i

Post by Nuno Sou » Sun, 25 Feb 2001 19:07:14




Quote:>slooooow. So, this is the next step. I also noticed that upgrading is
>basically taking dumps and re-importing into 8i after server has been
>upgraded. Are their any automated steps that I have missed or am I just
>crazy?? Wait, I just crazy, this is Oracle we are speaking about. The
>platforms that I am interested in are NT,2000, and HP Unix.

Hmmm, not so crazy, IMHO.  :-)
Anyways, here is what I've found so far (7->8i and 8->8i):
- Some of the earlier versions of 8i were quite buggy. 8.1.6 or later
is the one to use.
- Working set sizes (memory) for 8i blow up like crazy unless you're
using MTS and/or a few other tricks.
- Rowids are a worry inside the apps going from 7 to 8. PL/SQL code
seems to be shielded from this in 8i if the code is using the datatype
ROWID (automatically done).
- Handling of NULLS in PRO*C programs can be a problem.  There is an
option on the pre-compiler to behave like 7, but I'm more inclined to
have the code fixed.
- SQL*Loader is much, much faster in 8i.  Nearly 30% faster. Dunno
why, but it is.
- I have yet to see major improvments in parallel
INSERT/UPDATE/DELETE. But the parallel SELECT seems to work just fine
in 8.
- The optimizer is a bit iffy on 8.0 working with partitioned tables
and indexes.  Most of the time it needs help.  Unless you're prepared
to do full ANALYZE of all columns *AND* indexes.
- The optimizer in 8i is much better and takes better decisions.  But
some of the new hints are very badly explained, so thread carefully.
- Even in 8.1.6, there are still a few surprise "bugs"...

Cheers
Nuno Souto

http://www.users.bigpond.net.au/the_Den/index.html