Re: online index rebuilds

You can actually get an index full scan
(rather than fast full scan) for an offline index rebuild - and I thnk I decided the choice was cost-based even back in 8i.

Regards

Jonathan Lewis

http://www.jlcomp.demon.co.uk/faq/ind_faq.html The Co-operative Oracle Users' FAQ

http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html Cost Based Oracle: Fundamentals

http://www.jlcomp.demon.co.uk/appearances.html Public Appearances - schedule updated 10th Jan 2006

• Original Message ----- From: "Tanel Põder" <tanel.poder.003_at_mail.ee> To: <roger_xu_at_dp7uptx.com>; <joseph_at_amalrajinc.com>; "Bobak, Mark" <Mark.Bobak_at_il.proquest.com>; "ORACLE-L" <oracle-l_at_freelists.org> Sent: Monday, January 30, 2006 7:58 PM Subject: Re: online index rebuilds

Hi,

Thinking about why full table scan is required for online index rebuild... Maybe the potential index block splits are the reason why index FFS can't be used for online index rebuild? Consistent reads should overcome this issue though, but maybe there is something we don't know...

Btw, with offline index rebuild the decision whether to go with FTS or index FFS is also cost based (at least 10.2). If I have only single-column table indexed then the offline rebuild may do an FTS instead of fasf full index scan. (also, even in the case of fast full index scan, rows have to be sorted anyway, because index fast full scan doesn't guarantee an ordered result).

Tanel.

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