Re: is rebuilding indexes necessary after import?

Comments below

• Original Message ----- From: "stephen booth" <stephenbooth.uk_at_gmail.com> To: <mark_at_bobak.net> Cc: <sjaffarhussain_at_gmail.com>; "Active DBA" <oracle-l_at_freelists.org> Sent: Wednesday, December 22, 2004 6:29 PM Subject: Re: is rebuilding indexes necessary after import?

On Wed, 22 Dec 2004 02:37:25 -0500, Mark J. Bobak <mark_at_bobak.net> wrote:
> No, because import does not really "import" indexes. It issues a create
> index statement. So, the indexes are freshly built at the end of an
> import.
> -Mark

That begs the question, when is the create index statement issued? 'Create table, create index, import rows' and 'create table, import rows, create index' could lead to different results in terms of index efficiency. If the order of the data is such that the leading edge of the index is monotonically increasing or decreasing then you'll probably get an unbalanced and inefficient index (the same as you do with any increasing indexed value) if the index is created before the before the rows are imported and isn't reverse key.

Hi Stephen,

Monotonically increasing indexes do not become unbalanced and in the vast majority of cases, don't become inefficient.

Please take a look at :
http://www.actoug.org.au/Downloads/oracle_index_internals.pdf

One day, the message will get through.

One day ...

Cheers

Richard

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