Hi Ryan 1) The OP is probably using 8i. Therefore he cannot use system stats = anyway. 2) As usually it depends on your system... I did very good experiences = with them! The impact on the CBO can be huge. The most evident is that = db_file_multiblock_read_count isn't used for costing full table scan. Chris >-----Original Message----- >From: oracle-l-bounce@xxxxxxxxxxxxx = [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of >ryan_gaffuri@xxxxxxxxxxx >Sent: 21 October 2004 15:31 >To: JozeS@xxxxxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx >Cc: Joze Senegacnik >Subject: RE: Why the optimizer is not choosing the best plan? > >we are using system stats here and we have noticed absolutely no = difference whatsoever in oracles >ability to make the best plan over using optimizer parameters. I've = also noticed that even with bad >optimizer init.ora settings in 9.2 the CBO is still write about 99% of = the time. >with decent settings that improves to 99.5% of the time. so if system = stats helps its minimal. > >-------------- Original message -------------- > >> If you are on 9i then you should try to gather system statistics. = This =3D >> may change the join method from NL to HJ. >> >> Regards, Joze=3D20 >> >> -----Original Message----- >> From: oracle-l-bounce@xxxxxxxxxxxxx =3D >> [mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Sami Seerangan >> Sent: Wednesday, October 20, 2004 9:49 PM >> To: Oracle Discussion List >> Subject: Why the optimizer is not choosing the best plan? >> > >-- >http://www.freelists.org/webpage/oracle-l -- http://www.freelists.org/webpage/oracle-l