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Home -> Community -> Mailing Lists -> Oracle-L -> 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?
I am running EE 9.2.0.3 on Solaris 2.8.
Trace file for IOT:
WAIT #0: nam='db file sequential read' ela= 5828 p1=15 p2=509603 p3=1
WAIT #0: nam='db file sequential read' ela= 16070 p1=17 p2=1063439 p3=1
WAIT #0: nam='db file sequential read' ela= 13220 p1=16 p2=39872 p3=1
Trace file for Heap:
WAIT #3: nam='db file scattered read' ela= 1810 p1=27 p2=32645 p3=16
WAIT #3: nam='db file scattered read' ela= 1648 p1=27 p2=32661 p3=16
WAIT #3: nam='db file scattered read' ela= 1866 p1=27 p2=32677 p3=16
Thanks for your help,
Rick Stephenson
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