Chris/ Wolfgang, Thanks for your replies. Chris, U are right .. It isnt a FTS, its a Full Partition Scan. The autotrace output is: TABLE ACCESS (FULL) OF 'PART_TAB' (Cost=8412 Card =19 Bytes=2109) The plan_table clearly shows thats it will scan just one partition and not the full table. Still that behaviour is not as expected. The table access(full) run takes about 1:56 mins .. whereas if i give the index hint, it takes about 0:35 mins. ( I had initially thought that this happens only when the input value is a non-existent one.. maybe thats forcing a full-partn-scan. But thats not the case. It happens randomly even for values that do exist in the table.). Wolfgang, user@DB1 > show parameter cursor NAME TYPE VALUE ------------------------------------ ----------- ------ cursor_sharing string EXACT cursor_space_for_time boolean FALSE open_cursors integer 1000 session_cached_cursors integer 0 I collect statistics using the following ( once a week) : dbms_stats.gather_schema_stats(ownname=> 'DBOWNER', estimate_percent => DBMS_STATS.AUTO_SAMPLE_SIZE, method_opt => 'FOR ALL COLUMNS SIZE AUTO', cascade => TRUE); Regards Sanjay On 10/14/05, Wolfgang Breitling <breitliw@xxxxxxxxxxxxx> wrote: > > You don't, by any chance, have set cursor_sharing to force or similar? > How did you gather the table statistics? "options=>'gather auto'" ? > > Sanjay Madan wrote: > > > Chris, > > > > > > There is an associated problem too. I am not sure whether the 2 are > related. > > An autotrace output of FTS or INDX scan doesn't seem to actually > > guarantee an actual run as per the autotrace plan. > > > > i set db_file_multiblock_read_count to 16 with an alter session ( its 32 > > right on on the db). THAT makes the autotrace output show an INDX scan > > for the same 1234561 for which it shows a FTS with a > > db_file_multiblock_read_count = 32. > > (block_size is 8192). HOWEVER, the actual run timings for both the runs > > are quite similar. > > But if I specify an Index-hint, it runs in a fraction of that time ( > > irrespective of whether the db_f_m_r_c is set to 16 or 32 ... > > > > > -- > Regards > > Wolfgang Breitling > Centrex Consulting Corporation > www.centrexcc.com <http://www.centrexcc.com> >