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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Export of IOT very slow
Perhaps there was a deliberate choice in the
spec to make IOT export ordered, and therefore
risk it being much slower so that IOT import
would import data in index order, and
therefore be much faster with far fewer leaf
block splits.
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk/faq/ind_faq.html The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/seminar.html Optimising Oracle Seminar - schedule updated May 1st
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?
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