Re: How to best reset a column to null on very large tables.

From: Mark D Powell <Mark.Powell_at_eds.com>
Date: 18 Mar 2005 08:01:30 -0800
Message-ID: <1111161690.079998.38260@o13g2000cwo.googlegroups.com>

The ideas of dropping the column and adding it back involves a lot of work. And a column drop is for every row or none. You problem description makes it seem that the columns to be nullified may belong to only a specific customer and not all rows.

What you are doing now sounds reasonable.

Are any of the columns in question indexed? Null values are not indexes so if you have one of two columns that can be used as drivers for the operation indexing them may help greatly for the 10k to 50k requests. You would probably want to full scan for the 15M out of 20M deletes.

PQO is definitely a consideration for the big deletes.

HTH -- Mark D Powell -- Received on Fri Mar 18 2005 - 10:01:30 CST