exp performance question ( direct=y)

From: Guang Mei <zlmei_at_hotmail.com>
Date: Fri, 22 Jun 2001 09:26:03 -0700
Message-ID: <F001.00333D10.20010622085552@fatcity.com>

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:

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

Thanks.

Guang

here is my orcle dump file's time stamp: (dmp.1 and dmp.2 are from direct=y, dmp.3, dmp.4 and dmp.5 are from direct=n).

-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: Guang Mei
INET: zlmei_at_hotmail.com

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