RE: Export of IOT very slow
- From: "Khedr, Waleed" <Waleed.Khedr@xxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 26 May 2004 17:16:48 -0400
Interesting!
Could it be a result of bad settings for the overflow segment (you have
an overflow segment that requires a single block visits similar to the
chained rows situation for tables)?
Waleed
-----Original Message-----
From: Rick Stephenson [mailto:RStephenson@xxxxxxxx]=20
Sent: Wednesday, May 26, 2004 5:04 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Export of IOT very slow
Why does an IOT only allow for 1 block read at a time to extract data
during
an export. I have an IOT with 250 Million rows that takes 24 hours to
export, whereas, I have a heap table with 12 million rows that takes 6
minutes to export. If I extrapolate that out, the heap table would take
roughly 2 hours to finish with 250 million rows. I decided to trace the
processes and noticed that the IOT export will only read 1 block at a
time,
whereas the heap reads in 16 blocks at a time. Is there a way to force
the
"sequential" read to grab 16 blocks at a time?
=20
I am running EE 9.2.0.3 on Solaris 2.8.
=20
Trace file for IOT:
WAIT #0: nam=3D'db file sequential read' ela=3D 5828 p1=3D15 p2=3D509603 =
p3=3D1
WAIT #0: nam=3D'db file sequential read' ela=3D 16070 p1=3D17 =
p2=3D1063439 p3=3D1
WAIT #0: nam=3D'db file sequential read' ela=3D 13220 p1=3D16 p2=3D39872 =
p3=3D1
=20
Trace file for Heap:
WAIT #3: nam=3D'db file scattered read' ela=3D 1810 p1=3D27 p2=3D32645 =
p3=3D16
WAIT #3: nam=3D'db file scattered read' ela=3D 1648 p1=3D27 p2=3D32661 =
p3=3D16
WAIT #3: nam=3D'db file scattered read' ela=3D 1866 p1=3D27 p2=3D32677 =
p3=3D16
=20
Thanks for your help,
=20
Rick Stephenson
=20
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