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RE: exp performance question ( direct=y)

From: Mohammad Rafiq <rafiq9857_at_hotmail.com>
Date: Fri, 22 Jun 2001 14:42:00 -0700
Message-ID: <F001.003348AA.20010622144042@fatcity.com>

Please check export parameter RECORDLENGTH and try export with maximum allowable limit of your OS system with direct=y . On some OS limit is 65535 and see if it improves export time..
Regards
Rafiq

Reply-To: ORACLE-L_at_fatcity.com
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> Date: Fri, 22 Jun 2001 13:06:07 -0800

Thanks to all who helped me get a clear understanding of the direct=Y option for the exp utility.
I feel good, it is Friday and I have learned something today. ROR mô¿ôm

 >>> cspence_at_FuelSpot.com 06/22/01 04:44PM >>> No, direct only effects two things, the way oracle exports the data (avoiding character conversions and buffering) and the format of the file. The size and import speed of the export are effect only but .0001% or so. Basically insignificant.

"Walking on water and developing software from a specification are easy if both are frozen."

Christopher R. Spence
Oracle DBA
Fuelspot

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

Sent: Friday, June 22, 2001 3:01 PM
To: Multiple recipients of list ORACLE-L

I thought that DIRECT=Y was for imports only. It makes since because in the import you are placing the data directly into the blocks with out a redo log.
  I have no idea why there was a difference in the times unless it was the extra overhead for a command that was not used. ROR mª¿ªm

 >>> zlmei_at_hotmail.com 06/22/01 12:55PM >>> Oracle : 8.0.5
Platform : Sun

Currently we have cron job every night (starting from 11pm) to do export. I changed the setting "direct" to "y" two days ago while leaving all other parameters unchanged, hoping to gain some performance. I am a bit surprused to find that it did not. It actually took longer to create dump file with less data to export. The whole exp process takes about 2 hours to finish. Yes, there could be lots of other unix processes running during that time. But I would still expect to see some improvement because we are doing this way for quite a while. So my questions are:

  1. From your "real" export experience, how much performance boost did you see when you set "direct=y"?
  2. If "direct=y" improves the performance, why would anyone want to use "direct=n"?

Thanks.

Guang

-rw-rw-r-- 1 mt prog 1042197132 Jun 18 01:05 oracle.dmp.5.gz
-rw-rw-r-- 1 mt prog 1042375633 Jun 19 01:04 oracle.dmp.4.gz
-rw-rw-r-- 1 mt prog 1042556662 Jun 20 00:25 oracle.dmp.3.gz
-rw-rw-r-- 1 mt prog 1034773279 Jun 21 01:17 oracle.dmp.2.gz
-rw-rw-r-- 1 mt prog 1035237986 Jun 22 01:22 oracle.dmp.1.gz

--here is the parameter file:

BUFFER = 64000
COMPRESS = Y
CONSISTENT = N
CONSTRAINTS = Y
DIRECT = Y
FILE = /oracle/exports/oracle.dmp.pipe
#FULL = Y
GRANTS = Y
INDEXES = Y
LOG = /oracle/exports/export.log
ROWS = Y
USERID = xxx/yyy
OWNER = (aaa,bbb)



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Author: Mohammad Rafiq
  INET: rafiq9857_at_hotmail.com

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