Oracle FAQ Your Portal to the Oracle Knowledge Grid

Home -> Community -> Mailing Lists -> Oracle-L -> RE: Rebuilding database to change block size

RE: Rebuilding database to change block size

From: Gurgaon, DBA (CAP, GECSI, CONTRACTOR) <>
Date: Wed, 7 Jun 2000 10:19:00 +0530
Message-Id: <>

Create new database after changing db_block_size in init.ora. initially create only system tablespace,redo logfiles and a single big rollback segment and after this just import the data using sys.This will create all your other tablespaces using old datafiles.So no need to remove old datafiles also.

-----Original Message-----
From: Miller, Jay [] Sent: Tuesday, June 06, 2000 10:21 PM
To: Multiple recipients of list ORACLE-L Subject: Rebuilding database to change block size

Okay, we finally got enough storage space to hold an export of our datawarehouse so I'm going to change the block size from 4 to 16.

Obviously I'm testing this on a small play database first, but I've never done this before so I have several questions and would welcome any advice/comments/criticisms. Here's what I was thinking of:

  1. Do a full export (consistent=y) as sys. Backup control file to trace
    (just as an extra precaution).
  2. Shutdown database.
  3. Cold backup of all files.
  4. Drop all datafiles,control files, redo logs. Any other cleanup necessary? Or since the CREATE DATABASE command will erase data in existing datafiles, can I just skip this step entirely?
  5. Change db_block_size in init.ora file
  6. Start database in NOMOUNT mode.

Here's where I'm on somewhat thinner ice: 7. Issue create database command. Is there a way to generate this automatically from the existing database? It's easy enough to write from scratch but I'd rather not take chances with typos if I don't have to. 8. Change sys and system passwords.
9. I definitely want to precreate a few tablespaces where I want to change the initial extent parameter. Is it necessary to precreate all tablespaces and users (I can generate that script very easily)? 10. Import database as sys.

Okay, what am I missing?

Thanks to all,

Author: Miller, Jay

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
To REMOVE yourself from this mailing list, send an E-Mail message
to: (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L

(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
Received on Tue Jun 06 2000 - 23:49:00 CDT

Original text of this message