Mass updates to production tables (NULL to non-NULL)

From: Jesse, Rich <Rich.Jesse_at_qtiworld.com>
Date: Mon, 25 Nov 2002 13:03:53 -0800
Message-ID: <F001.0050B49C.20021125130353@fatcity.com>

I've got a real hot project (8.1.7.2 on HP/UX 11.0) that needs to have NULLs converted to spaces on three different columns. Each is a CHAR, so I shouldn't need to worry about chaining, since that column's full size has already been allocated in the block, right? But the first column has 1.2M NULLs out of 1.45M rows.

My first test was to just UPDATE mytable SET mycol = ' ' WHERE mycol IS NULL, after removing the index on that column. Seeing as there were many more rows updated than I had anticipated, I was going to test the UPDATE using a cursor, and committing at every 10K rows (~120 total commits) to reduce rollback and locking issues.

Thoughts? Since this table is used for time-and-attendance and directly affects payroll, downtime isn't possible.

TIA! Rich

Rich Jesse                           System/Database Administrator
Rich.Jesse_at_qtiworld.com              Quad/Tech International, Sussex, WI USA

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Author: Jesse, Rich
  INET: Rich.Jesse_at_qtiworld.com

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