Oracle Consulting Oracle Training Development

Remote DBA

Remote DBA Plans  

Remote DBA Service

Remote DBA RAC

   
Remote DBA Oracle Home
Remote DBA Oracle Training
Remote DBA SQL Tuning Consulting
Remote DBA Oracle Tuning Consulting
Remote DBA Data Warehouse Consulting
Remote DBA Oracle Project Management
Remote DBA Oracle Security Assessment
Remote DBA Unix Consulting
Burleson Books
Burleson Articles
Burleson Web Courses
Burleson Qualifications
Oracle Links
Remote DBA Oracle Monitoring
Remote DBA Support Benefits
Remote DBA Plans & Prices
Our Automation Strategy
What We Monitor
Oracle Apps Support
Print Our Brochure
Contact Us (e-mail)
Oracle Job Opportunities
Oracle Consulting Prices





   

 

 

 

Remote DBA services

Remote DBA Support

Remote DBA RAC

Remote DBA Reasons

Remote Oracle Tuning

Remote DBA Links

Oracle DBA Support

Oracle DBA Forum

Oracle Disaster

Oracle Training

Oracle Tuning

Oracle Training

 Remote DBA SQL Server

Remote MSSQL Consulting

Oracle DBA Hosting

Oracle License Negotiation

 

 


 

 

 

        
 

 Oracle Files for Loading into External Tables
Oracle Tips by Burleson Consulting

Oracle 11g Grid & Real Application Clusters by Rampant TechPress is written by four of the top Oracle database experts (Steve Karam, Bryan Jones, Mike Ault and Madhu Tumma).  The following is an excerpt from the book.

Files for Loading into External Tables

External tables allow direct access of data located in the operating system level files by using the SQL interface within the database. It is a way of reading and writing files into and out of the database. Note that one cannot write to an existing external table.  Data stored in operating system level files (ASCII filer) can be accessed as if they are a table with rows and columns. Joins and views can be constructed with data in the O/S file and logical database tables.

 

For all practical purposes, external tables act the same as the usual tables; however, the data is not stored with the Oracle data files. External tables are a great way to load the data into a database and do data processing. Inserts, updates, and index creation are not allowed on an external table.  A DROP TABLE statement issued against an external table removes the table metadata only; the operating system file is not removed.

 

There is no restriction as to where the external table data file has to be located. In a RAC database system, it can be located on the local file system or on shared disk. For the sake of concurrent access, it becomes more meaningful to keep the external table file on a shared storage. This allows for transparent access to the external table so that any instance in the RAC database should be able to read it at the operating system level (ASCII). This is possible only if the external table file is located on a shared disk.

Oracle Cluster Registry (OCR)

The OCR contains cluster and database configuration information for RAC and Cluster Ready Services (CRS) such as the cluster node list, instance to node mapping, and CRS application resource profiles.

 

The OCR is a shared file located in a cluster file system. When not using a cluster file system, the OCR file can be located on a shared raw device in UNIX-based systems or a shared logical partition in Windows environments. If more than one database is created on the cluster, they all share the same Oracle cluster registry.

Voting Disk

The voting disk file must reside on shared storage.  The voting disk file manages information for node membership.  Oracle recommends using multiple voting disk files.

ORACLE_HOME Files (Oracle Binaries)

Typically, every instance in Oracle 11g RAC will have its own ORACLE_HOME and a set of exclusive binaries. However, the Oracle binaries are located either on a local file system or on a clustered file system. Locating the Oracle home (binaries) on a clustered file system provides easier management by keeping a single copy of Oracle home supporting all the instances.

 

A common Oracle home for multiple instances has some advantages because it helps to easily expand the nodes and shrink the nodes as needed. It helps the dynamic addition and expansion of nodes without bothering with a fresh install of the Oracle binaries for the new instance. This feature is useful for large clusters, and it fits into the grid strategy of easier addition and reduction of computing resources.

UNDO Tablespace Files

UNDO tablespaces are special tablespaces that have system undo segments. They contain before images of blocks involved in uncommitted transactions. As such, they are the primary support structure allowing a transaction to rollback if the decision is made to not commit the transaction.  Tables and indexes cannot be created in the undo tablespace.  A database can have more than one undo tablespace, but only one can be used at one time. Automatic undo management is the default mode for an 11g database.  DBCA will automatically create an undo tablespace named UNDOTBS1.

     

Remote DBA Service
 

Oracle Tuning Book

 

Advance SQL Tuning Book 

BC Oracle support

Oracle books by Rampant

Oracle monitoring software

 

 

 

 

 

 

 

 

 

BC Remote Oracle Support

Remote DBA

Remote DBA Services

Copyright © 1996 -  2013 by Burleson. All rights reserved.

Oracle® is the registered trademark of Oracle Corporation.