Tip

Compressing Oracle exports on the fly

Here is how to create compressed Oracle export files on the fly even though the export utility does not support writing to the Unix standard output stream. It is been tested on versions 7.3 though 8.1. It should also work on 9i, or any version of Oracle that runs on Unix.

Instead of piping the export file directly into the unix compress utility, create a named pipe with the mkfifo command and specify that as the name of the export file. Prior to starting the export, run a compress command in background that reads from the named pipe and writes to a regular file. That file will be created compressed on the fly.

To import from the compressed file to just the opposite. Create a named pipe and use zcat or uncompress in background to read from the compressed file and redirect the output to the named pipe. Then start the import utility and specify the named pipe as the import file.

This tip is useful because it allows you to created compressed export files directly without first having to run the export then compress the output file. To do it the traditional way requires enough disk space to hold both the compressed and uncompressed files simultaneously. My method bypasses the uncompressed file altogether.

To export to a compressed file:

mkfifo pipe.dmp
compress < pipe.dmp > expdat.dmp.Z &
exp user/passwd full=y file=pipe.dmp
To import the same file:
mkfifo pipe.dmp
uncompress < expdat.dmp.Z > pipe.dmp &
imp

    Requires Free Membership to View

user/passwd full=y file=pipe.dmp

For More Information

  • Feedback: E-mail the editor with your thoughts about this tip.
  • More tips: Hundreds of free Oracle tips and scripts.
  • Tip contest: Have an Oracle tip to offer your fellow DBAs and developers? The best tips submitted will receive a cool prize -- submit your tip today!
  • Ask the Experts: Our SQL, database design, Oracle, SQL Server, DB2, metadata, and data warehousing gurus are waiting to answer your toughest questions.
  • Forums: Ask your technical Oracle questions--or help out your peers by answering them--in our active forums.
  • Best Web Links: Oracle tips, tutorials, and scripts from around the Web.

This was first published in October 2002

There are Comments. Add yours.

 
TIP: Want to include a code block in your comment? Use <pre> or <code> tags around the desired text. Ex: <code>insert code</code>

REGISTER or login:

Forgot Password?
By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy
Sort by: OldestNewest

Forgot Password?

No problem! Submit your e-mail address below. We'll send you an email containing your password.

Your password has been sent to:

Disclaimer: Our Tips Exchange is a forum for you to share technical advice and expertise with your peers and to learn from other enterprise IT professionals. TechTarget provides the infrastructure to facilitate this sharing of information. However, we cannot guarantee the accuracy or validity of the material submitted. You agree that your use of the Ask The Expert services and your reliance on any questions, answers, information or other materials received through this Web site is at your own risk.