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RE: Huge import takes a long time

From: Marquez, Chris <>
Date: Thu, 21 Jul 2005 11:16:44 -0400
Message-ID: <B30C2483766F9342B6AEF108833CC84E05BD5EA4@ecogenemld50.Org.Collegeboard.local>

Without knowing or looking at the specifics of your situation or the limitations of partition IMPorts, these are small and large things that have helped me and I have used many times in the past and even within the last week to complete a large db migration to a new platform (boy, I will be glad when RMAN can just move/copy/clone (data) files from OS-a to OS-b!!!)

Be forewarned about using "_[parameter]" parameters! Using them and having a db/server crash during use, means corrupt database for sure. Un-set them when finished *AND* make sure you can switch / cycle all redo (arch logs)...test, test, test. You have been warned.

Good luck...hth

Chris Marquez
Oracle DBA


Set IMP parameter COMMIT = Y.
Set IMP parameter RECORDLENGTH >= EXP RECORDLENGTH value. Set IMP parameter BUFFER = MB (Set in the MB range not KB range)

Set IMP parameter STATISTICS = NONE (9i, n/a 8i)

Set IMP parameter RECALCULATE_STATISTICS = N. (8i, n/a 9i) Set IMP parameter ANALYZE = N. (8i, n/a 9i)

Set IMP parameter INDEXES = N (Import them later...separately)

Set init.ora parameter LOG_ARCHIVE_START = FALSE *&*   alter database noarchivelog;
Set init.ora parameter _disable_logging = TRUE (Warning, this could be dangerous and unrecoverable in failure.  Backup immediately after import - * Redo records (to disk) will NOT be generated (redo WAS generated in the log buffer.) [Even with _disable_logging you still "switch" logs when they get "full"])
Set init.ora parameter _wait_for_sync = FALSE (Warning, this could be dangerous and unrecoverable in failure.  Backup immediately after import - _wait_for_sync: Wait_for_sync is an oracle generic parameter which, when set to  false, will allow the system to complete commits without waiting  for the redo-log buffer flushes to complete.)

Make redo logs enormous; 500MB, 1GB, etc.

Use Locally Managed Tablespaces on target database.

Chris Marquez
Oracle DBA

-----Original Message-----

From: on behalf of Kline.Michael Sent: Thu 7/21/2005 10:00 AM
Subject: Huge import takes a long time  

I've got a massive import that takes a long time. This is one I'd love to drop and recreate the index, but that alone would probably be almost a terabyte, so that is out of the question.  

This is a table partitioned by month and a normal partition is about 20-24GB. As it's coming in, it's getting a lot of I/O wait on the index datafiles, but only the datafiles of that partition. The index is also partitioned.  

This is now, so just how high can you set up the buffer?  

Are there any other "tricks"?  

As I get to the "end" of the partition my import rate is getting to be 2-3GB per day.  


Michael Kline
Database Administration
SunTrust Technology Center
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Richmond, Virginia 23227
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Cell 804.744.1545

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-- Received on Thu Jul 21 2005 - 10:22:18 CDT

Original text of this message