We has problems with another undocumented parameter that changed when we migrated to 9i in August last year. _B_TREE_BITMAP_PLANS change from false to true and caused a number of issues with sub-optimal execution plans.
Another possible trap for the unwary ... Cheers Richard ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Thursday, October 02, 2003 2:54 AM > One of the undocumented init.ora parameters that changed from 8 to 9 is > "_UNNEST_SUBQUERY" (from false to true). You could try if that is the > culprit. Of course, since it is an undocumented parameter, get the blessing > from Oracle support before using it in a production database. > > At 10:09 AM 10/1/2003, you wrote: > >Joan, what is the difference in the plans? What specific feature > >made the difference? Are the values of > >optimizer_index_cost_adj and optimizer_index_caching same on both > >versions? How about histograms? What is with > >db_file_multiblock_read_count,sort_area_size and hash_area_size? Is > >everything same as in 8i? May be setting of those parameters can be > >tweaked to your benefit? > > > >On Wed, 2003-10-01 at 11:54, Joan Hsieh wrote: > > > Kirti, > > > > > > I had upgraded a database from 8.1.7.4 to 9.2.0.4. Before the upgrade, > > > performance is good. After upgrade, one query run time from 2 min to 12 > > > hours. Of course, I re-analyzed all tables and indexes. The explain plan > > > changed from hash join to nested-loop. All the parameters are same. So I > > > have to put optimized_feature_enable=8.1.7 to make run normal as usual. > > > I hate to disable the new feature, but no choose. > > Wolfgang Breitling > Oracle7, 8, 8i, 9i OCP DBA > Centrex Consulting Corporation > http://www.centrexcc.com > > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Wolfgang Breitling > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Richard Foote INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
