t is cross ref table betwen t1 and t3 , so 3rd join can't be added (
t1.id = t3.id ).
Well, I guees Mark has the right when saying that at least one table must
be FTS as driver table in the
absence of filters.
This is exactly what customer noticed too - by adding additional filters
FTS is completelly gone.
Mistery solved I guess.
Thanks all, especially Mark.
Rgrds, rm.
On 5/18/06, Bobak, Mark <Mark.Bobak@xxxxxxxxxxxxxxx> wrote:
>
> Um, ok. Why would you not expect at least one FTS? There is no filter
> predicate, therefore, the driving table MUST do FTS. Depending on
> statistics, the optimizer may decide that utilizing the join predicate to
> drive a index access is efficient to join the second table to the driving
> table, or it may decide to FTS the second table as well.
>
> However, in that query, at least one table MUST be full scanned.
>
> -Mark
>
>
> *--*
> *Mark J. Bobak*
> *Senior Oracle Architect*
> *ProQuest Information & Learning*
>
> For a successful technology, reality must take precedence over public
> relations, for Nature cannot be fooled. --Richard P. Feynman, 1918-1988
>
>
> ------------------------------
> *From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
> *On Behalf Of *Ranko Mosic
> *Sent:* Thursday, May 18, 2006 2:06 PM
> *To:* Wolfgang Breitling
> *Cc:* _oracle_L_list
>
> *Subject:* Re: Index not used
>
>
> Even the following query does FTS:
> SELECT *
> > 2 FROM tab1 t1 ,
> > 3 tab2 t2
> where t1.id = t2.id
>
>
> rm
>
>
> On 5/17/06, Wolfgang Breitling < breitliw@xxxxxxxxxxxxx> wrote:
>
> > There is no predicate for tab2, the smallest of the three tables,
> apart from the
> join predicate. Are there usable indexes on tab1.type and
> tab3.start_date?
> Any changes if you add the transitive closure predicate (the optimizer
> does not
> do this (yet)):
> t1.id = t2.id and t2.id = t3.id => t1.id = t3.id
> It opens additional access paths.
>
> Quoting Ranko Mosic < ranko.mosic@xxxxxxxxx>:
>
> > Hi List,
> >
> > SELECT *
> > 2 FROM tab1 t1 ,
> > 3 tab2 t2 ,
> > 4 tab3 t3
> > 5 WHERE t1.id = t2.id
> > 6 AND t2.id = t3.id
> > 7 AND t1.type IN
> > 8 ('A','B','C')
> > 9 AND t3.type = 'A'
> > 10* AND t3.start_date = '01-APR-2004'
> >
> > All join cols are indexed on leading cols. There is FTS on t2 . Stats
> are
> > fresh and computed .
> > Why FTS on t2 ? ( v 9.2 ).
> > --
> > Regards,
> > Ranko Mosic
> > Contract Senior Oracle DBA
> > B. Eng, Oracle 10g, 9i Certified Database Professional
> > Phone: 416-450-2785
> > email: mosicr@xxxxxxxxxx
> >
>
>
http://ca.geocities.com/mosicr@xxxxxxxxxx/ContractSeniorOracleDBARankoMosicMain.html
> >
>
>
> --
> regards
>
> Wolfgang Breitling
> Oracle 7,8,8i,9i OCP DBA
> Centrex Consulting Corporation
> www.centrexcc.com
>
>
>
>
> --
>
> Regards,
> Ranko Mosic
> Contract Senior Oracle DBA
> B. Eng, Oracle 10g, 9i Certified Database Professional
> Phone: 416-450-2785
> email: mosicr@xxxxxxxxxx
>
http://ca.geocities.com/mosicr@xxxxxxxxxx/ContractSeniorOracleDBARankoMosicMain.html
>
>
--
Regards,
Ranko Mosic
Contract Senior Oracle DBA
B. Eng, Oracle 10g, 9i Certified Database Professional
Phone: 416-450-2785
email: mosicr@xxxxxxxxxx
http://ca.geocities.com/mosicr@xxxxxxxxxx/ContractSeniorOracleDBARankoMosicMain.html
