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Use pipe to unload/load database tables

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Chushia
Frequent Advisor

Use pipe to unload/load database tables

I have a server rp5430 with HP-UX 11i running Informix IDS 9.40. I want to reclaim some database storage by performing a table reorg. I'm using a named pipe for unload table in one shell and simultaneously load table in another shell trying to eliminate the need of intermediate large files.

I tested on a smaller table and the result of using pipe is not what I expected. The pipe is as big as I unload to a data file, generating a large intermediate file. On top of that, the load shell can terminate while the unload is not finished. These just don’t show much benefit of using pipe over a normal way of “unload to file, and then load back from the file”. I think I didn’t use pipe properly. Could you gurus give me some advice ?

Thanks,
Chushia
6 REPLIES
Hein van den Heuvel
Honored Contributor
Solution

Re: Use pipe to unload/load database tables

>> I think I didnâ t use pipe properly. Could you gurus give me some advice ?

If you show me yours, then I'll show you mine.

Seriously, how exactly did you use the pipe?
Did you use mkfifo, or mknod name p ?

fwiw,
Hein.


Chushia
Frequent Advisor

Re: Use pipe to unload/load database tables

Thank you Hein,

I forgot to do a mkfifo ... now it's working as I expected.

Thanks!
Chushia
TwoProc
Honored Contributor

Re: Use pipe to unload/load database tables

Hein, is there a difference?
All I've ever used is mknod -p. I've read the man pages, and I fail to see a difference.
Can you enlighten me as to why mkfifo is different/better thank mknod -p? Other than in this case, it works... but why?
We are the people our parents warned us about --Jimmy Buffett
Dennis Handly
Acclaimed Contributor

Re: Use pipe to unload/load database tables

>TwoProc: why mkfifo is different/better than mknod p?

Because mkfifo(1) does what its name implies and nothing else. It also has -p and -m.

Also its option is on the correct side of the filename (left).
Hein van den Heuvel
Honored Contributor

Re: Use pipe to unload/load database tables

As Dennis replied, mkfifo seems more descriptive.That's all.
Hein.

TwoProc
Honored Contributor

Re: Use pipe to unload/load database tables

Thnks Dennis and Hein
We are the people our parents warned us about --Jimmy Buffett