Oracle-L: RE: Mass updates to production tables (NULL to non-NULL)

From: mantfield <mantfield_at_connexus.net.au>
Date: Mon, 25 Nov 2002 17:08:57 -0800
Message-ID: <F001.0050B835.20021125170857@fatcity.com>

If you're going the PDML route, don't forget to increase the initrans of the tables and indices, since each Parallel Execution slave will have its own entry into the block transaction list, and this in itself could result in that annoying ORA-01555 error we see.

Regards :

Ferenc Mantfeld

-----Original Message-----

From:	Deshpande, Kirti [SMTP:kirti.deshpande_at_verizon.com]
Sent:	Tuesday, November 26, 2002 11:19 AM
To:	Multiple recipients of list ORACLE-L
Subject:	RE: Mass updates to production tables (NULL to non-NULL)

I would consider PDML to get the job done faster, provided there are enough resources.
Using a cursor seems like a good idea, but avoid fetching across commits. We are going through a similar exercise, adding 10000000 to a cust_id field to denote the source of the data, and Developers complained about ORA-1555. Asked them not to commit as existing rollback segments and space were adequate ;)

Good Luck,

Kirti

-----Original Message-----

Sent: Monday, November 25, 2002 3:04 PM
To: Multiple recipients of list ORACLE-L

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: mantfield
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