Archives of the TeradataForum
Message Posted: Fri, 14 Mar 2003 @ 17:57:46 GMT
| 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.