Re: RBO changes plan from 8i to 9i

  • From: "LS Cheng" <exriscer@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Fri, 14 Jul 2006 08:53:58 +0200

Hi Alex

Those changes only affects very simple Deletes such as

delete x where x_id = 1

The predicate must be part or all of a single index, if there are references
to other columns then you will still see table access. I am not sure what
this is called.

And by the way to disable nested loop parallel scan with multi join keys you
can set _multi_join_key_table_lookup to FALSE and leave
_table_lookup_prefetch_size with its default value. I am not sure which is
betetr idea, I would guess modifying _multi_join_key_table_lookup might be a
better approach since I am not sure what other features you are disbaling by
setting _table_lookup_prefetch_size to cero.


Regards



On 7/13/06, amonte <ax.mount@xxxxxxxxx> wrote:

Hi again

I just noticed some minor changes in DELETE plans as well, instead of

DELETE STATEMENT    null
          DELETE    null

                TABLE ACCESS    BY INDEX ROWID
                INDEX    RANGE SCAN

in 8.1.7.4 I see now

DELETE STATEMENT    null
          DELETE    null
                INDEX    RANGE SCAN

Again it's very minor change, table access is no longer needed.

What is this new feature called...?

Thanks


Alex


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