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Message Posted: Fri, 14 Mar 2003 @ 17:57:46 GMT

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Subj:   Re: Deleting from a huge table
From:   Dennis Calkins

Anantaraman, Kumaran (K.) wrote:

  wall time in secs (mload = 75, insert-select = 2160)
AMP CPU (mload = 1686, insert-select = 39067)
Disk I/O (mload = 4305018, insert-select = 14124056)

  The table had 500 mill rows and I was deleting 100 mill (20%) on a WHERE on a non-PI column date column. There are no SIs, and there were no blocking during the runs. I am using V2R4.1  

  What could explain the above results?  


Insert select has to move the 80% of the rows which are remaining to a new table.

Multiload delete only needs to delete 20% of the rows.

Deleting 100 million rows is faster than writing 400 million rows.

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