Re: Incorrect Migrated/Chained rows...

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Wed, 28 Apr 2004 05:59:56 +0000 (UTC)
Message-ID: <c6nh8s$fsb$1@sparta.btinternet.com>

The number of columns is the most relevant point. A row defined with more than 250-ish columns is stored as up to 4 separate row pieces, and is therefore chained - even if all 4 pieces are in the same block.

If most of your rows are NULL after column 250(-ish), then the piece with all the nulls would not be required, which is why you would be able to see just a few thousand rows apparently chained after copying out 400,000 rows.

BUT - I discounted the 'long row' theory when I read your post, because when you re-copied the table, you had no chained rows. It seems like from your description, though, that Oracle may have changed the way it handles chaining when it is intra-block chaining - a couple of the things it did in 8.1 needed refinement.

-- 
Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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"MAK" <maks70_at_comcast.net> wrote in message
news:b7178504.0404271638.40945edc_at_posting.google.com...


> Thanks JL for your reply.

>

> > You don't quote an Oracle version - and oddities

> > like this can be highly version dependent.

> >

> Its 9.2.0.3.

>

> The table in question has 305 columns ( > 255) , should it make any

> difference?

> >

>

Received on Wed Apr 28 2004 - 00:59:56 CDT