Kumar Answer to your question depends upon the workload in your database. Most EBiz database will work just fine with sga_target and sga_max_size. If your workload is higher, then you do need to customize these parameters. I tend to take a safer approach and avoid excessive allocation changes between buffer cache and shared pool etc. I calculate, size of buffer cache, shared pool size, java pool size, stream pool size, and log buffer; then set values for these areas. Then leave some free space (few GBs) between the sum of these areas and sga_max_size. With this approach, we can use dynamic SGA feature and reduce the risk of memory moving between the areas excessively. Of course, you should monitor v$sga_dynamic_components and monitor the allocation change activity. Except memory area size parameters, I adhere to other parameters listed in bde_chk_cbo script. Cheers Riyaj Shamsudeen Principal DBA, Ora!nternals - http://www.orainternals.com - Specialists in Performance, Recovery and EBS11i Blog: http://orainternals.wordpress.com OakTable member http://www.oaktable.com Co-author of the books: Expert Oracle Practices<http://tinyurl.com/book-expert-oracle-practices/>, Pro Oracle SQL, Expert PL/SQL Practices<http://tinyurl.com/book-expert-plsql-practices> On Sun, Jul 17, 2011 at 3:35 AM, Kumar Madduri <ksmadduri@xxxxxxxxx> wrote: > Hi > I am upgrading from 11gR1 to 11gR2. As part of this, I am cleaning up some > init.ora parameters that exists from the older versions. > As per note 396009.1, the parameter db_cache_size should not be set. But I > noticed that when I unset it performance suffers for operations like data > pump and concurrent jobs (this is an ebiz 12.1.2 env) that fetch lot of > data. Some concurrent programs dont even run if the db_cache_size is not > set. > The predicament is that, Oracle Ebiz development swears by the document > 396009.1 ( > http://www.oracle.com/technetwork/apps-tech/collab2011-tuning-ebusiness-421966.pdf). > In this article, reference to 396009.1 is given and in this > > http://blogs.oracle.com/stevenChan/entry/recommended_database_parameters_updated_for_ebs_11 > > "Don't be fooled -- these changes are extremely important and can have > profound impact on the performance of your Apps database. All Apps DBAs > should spend some quality time comparing your current database settings with > the latest recommendations in this document." > but when you dont set them there are issues. > I want to follow oracle's recommendation but our experience shows that > db_cache_size cannot be unset. > Pasting this information from the note > > 4.2 Parameter Removal List for Oracle Database 11*g* Release 2 > > If they exist, you should remove the following parameters from your > database initialization parameters file for Oracle Database 11*g* Release > 2 (11.2.X). > _always_anti_join > _always_semi_join > _complex_view_merging > _index_join_enabled > _kks_use_mutex_pin > _new_initial_join_orders > _optimizer_cost_based_transformation > _optimizer_cost_model > _optimizer_mode_force > _optimizer_undo_changes > _or_expand_nvl_predicate > _ordered_nested_loop > _push_join_predicate > _push_join_union_view > _shared_pool_reserved_min_alloc > _sortmerge_inequality_join_off > _sqlexec_progression_cost > _table_scan_cost_plus_one > _unnest_subquery > _use_column_stats_for_function > always_anti_join > always_semi_join > background_dump_dest > core_dump_dest > db_block_buffers > *db_cache_size* > db_file_multiblock_read_count > DRS_START > enqueue_resources > event="10932 trace name context level 32768" > event="10933 trace name context level 512" > event="10943 trace name context forever, level 2" > event="10943 trace name context level 16384" > event="38004 trace name context forever, level 1" > hash_area_size > java_pool_size > job_queue_interval > large_pool_size > max_enabled_roles > nls_language > optimizer_dynamic_sampling > optimizer_features_enable > optimizer_index_caching > optimizer_index_cost_adj > optimizer_max_permutations > optimizer_mode > optimizer_percent_parallel > plsql_compiler_flags > plsql_native_library_dir > plsql_native_library_subdir_count > plsql_optimize_level > query_rewrite_enabled > rollback_segments > row_locking > sort_area_size > sql_trace > SQL_VERSION > timed_statistics > undo_retention > undo_suppress_errors > user_dump_dest > > > > Want to know the experience of others in setting/unsetting db_cache_size > > Thank you > Kumar > >