Optimising Oracle Imports
author: Martin "mpot" Pot
date: 25 October 2004
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Contents
Introduction
Aim of this Article
While recently upgrading a client's Oracle database from Oracle 7.3.4 to Oracle 8.1.7, the Oracle import was identified as an activity which took an extended period of time, resulting in a significant outage of some of the client's applications which relied on the database.
This article identifies Oracle configuration parameters that can be tuned to:
- significantly decrease the time required to migrate the database
- provide a performance improvement in normal operation
Decreasing the time taken to migrate the database will reduce the outage of any Oracle-dependant applications, allowing them to be returned to service sooner.
Scope
This document is specifically targeted at improving the import of Oracle databases, and also includes some configuration options to improve the performance of an Oracle database.
The scope of this document is limited to the following:
- Oracle 8.1.7 (also known as Oracle 8i)
- Windows 2000 / Windows 2003 Server
No performance testing was performed on a running database with and without the configuration changes described in this document. The primary purpose of these configuration changes is to reduce the data import duration. However, the changes should also provide a performance improvement on the normal operation the database.
While most of the configuration described in this document may be applicable for later versions of Oracle, it has not been tested.
Due to the changes and new features in Oracle 9i, some of the tuning suggestions in this document are not applicable for Oracle 9i and later versions.
Disclaimer
Sources
The configuration described in this document is the result of various discussions with Oracle DBAs, and from information contained in Oracle's MetaLink knowledge base.
Verify Configuration
You should verify that the configuration is appropriate for your database prior to implementing any configuration changes. Each database and site has different requirements, and the configuration described here is based on the configuration of one client's database.
Database Backup
Ensure you have a valid database backup prior to making any changes to the configuration of your database, and prior to performing the migration.
Review
An appropriately qualified Oracle DBA should review any configuration changes prior to implementation.
Read In Entirety
Read this entire document carefully before performing import, and refer to the referenced articles for more details and background information.
Background Info
Database Migration
When migrating a database from Oracle 7.3.4 to Oracle 8.1.7, the data and other objects are exported from the Oracle 7.3.4 database instance, and imported into a new Oracle 8.1.7 database instance.
pictorial representation of Oracle migration process
If migrating the database onto a new server, the process is simplified somewhat, as you can install the Oracle 8.1.7 server software, and build your database, prior to the migration itself, thus reducing the downtime of any applications. This also provides an easy back-out strategy, if anything were to go wrong during the migration, as you can easily revert back to the old database on the existing server.
If migrating the database from Oracle 7.3.4 to Oracle 8.1.7 on the same hardware, then you'll need to export the database, un-install Oracle 7.3.4, install Oracle 8.1.7, build a database instance, and then import the dump file.
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