How many more of these "undocumented" but seemingly crucial optimizer parameters has changed from 8i to 9i? I'd think these are a bit more important to know about.
Anyone have a list of these changed parameters? Are they noted in the 9i docs? boss > > 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). > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Todd Boss 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).
