Re: Fast Full Index Scan in 8.1.7

Cherie        
        You could turn it off using _fast_full_scan_enabled=false at the instance level. fast_full_scan_enabled is simply an underscore parameter in 8.1.7. But, I would turn on the event 10053 and run the statement to find why CBO is not using.. Could it be possible that this behaviour is due to poor index selectivity ?         alter session set events '10053 trace name context forever, level 1';

Thanks
Riyaj "Re-yas" Shamsudeen
Certified Oracle DBA
i2 technologies   www.i2.com

Cherie_Machler_at_gelco.com
Sent by: root_at_fatcity.com
09/07/01 06:55 AM
Please respond to ORACLE-L

        
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        Subject:        Re: Fast Full Index Scan in 8.1.7

I wanted to turn it off in testing so I could try some other indexes as an alternative.   I'm not sure that I trust it to make a good decision.

Even with an alternative index hint, it's not using the index I'm trying to get it to use, but rather the fast full index scan.  I can't see any typo but
maybe it just can't use that index with full full index scan enabled.

That's why I wanted to try and disable it and see what would happen.

CBO does some interesting things.  Every time I think I have a handle on some aspect of it, it changes and starts doing something different.

Thanks for your reply.

Cherie

                                                                                                                   
                    Jared Still                                                                                    
                    <jkstill_at_cybco       To:     ORACLE-L_at_fatcity.com, Cherie_Machler_at_gelco.com                    
                    n.com>               cc:                                                                       
                                         Subject:     Re: Fast Full Index Scan in 8.1.7                            
                    09/07/01 12:04                                                                                 
                    AM                                                                                             
                                                                                                                   
                                                                                                                   

The alternative is probably a full table scan.

Are you sure you want to turn it off?

I think you need to hint your SQL to do that.

Jared

On Thursday 06 September 2001 13:21, Cherie_Machler_at_gelco.com wrote:
> I had been using the FAST_FULL_SCAN_ENABLED initialization parameter in
an
> 8.0.4 database.
>
> Apparently this parameter is now obsolete in 8.1.7.2.   Seems as though I
> am getting the fast full index
> scans automatically now.  I'm not sure if I want them in all cases.   Is
> there a way to turn them off?
>
> Thanks,
>
> Cherie Machler
> Oracle DBA
> Gelco Information Network

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