| NAME | 8.1.7 | 9.2.0 | 10.2.0.1 |
| _trace_options | text | multiple | text |
| _db_block_adjchk_level | 78561536 | 78889216 | 78889216 |
| _always_semi_join | OFF | CHOOSE | CHOOSE |
| _ordered_nested_loop | FALSE | TRUE | TRUE |
| _optimizer_max_permutations | 80000 | 2000 | 2000 |
| query_rewrite_enabled | FALSE | FALSE | TRUE |
| _mmv_query_rewrite_enabled | FALSE | FALSE | TRUE |
| _index_join_enabled | FALSE | TRUE | TRUE |
| _table_scan_cost_plus_one | FALSE | TRUE | TRUE |
| _cost_equality_semi_join | FALSE | TRUE | TRUE |
| _new_initial_join_orders | FALSE | TRUE | TRUE |
| _optim_peek_user_binds | FALSE | TRUE | TRUE |
| _gs_anti_semi_join_allowed | FALSE | TRUE | TRUE |
| _optim_new_default_join_sel | FALSE | TRUE | TRUE |
| optimizer_dynamic_sampling | 0 | 1 | 2 |
| _pre_rewrite_push_pred | FALSE | TRUE | TRUE |
| _union_rewrite_for_gs | OFF | YES_GSET_MVS | YES_GSET_MVS |
| _generalized_pruning_enabled | FALSE | TRUE | TRUE |
| _optim_adjust_for_part_skews | FALSE | TRUE | TRUE |
| _optimizer_compute_index_stats | FALSE | FALSE | TRUE |
| _optimizer_filter_pred_pullup | FALSE | FALSE | TRUE |
| optimizer_features_enable | 8.1.7 | 9.2.0 | 10.2.0.1 |
| optimizer_mode | CHOOSE | CHOOSE | ALL_ROWS |
| _always_anti_join | OFF | CHOOSE | CHOOSE |
| _partition_view_enabled | FALSE | FALSE | TRUE |
| _b_tree_bitmap_plans | FALSE | TRUE | TRUE |
| _cpu_to_io | 100 | 0 | 0 |
| _optimizer_cost_model | IO | CHOOSE | CHOOSE |
| _optimizer_undo_cost_change | 8.1.7 | 9.2.0 | 10.2.0.1 |
| _optimizer_system_stats_usage | FALSE | TRUE | TRUE |
| _new_sort_cost_estimate | FALSE | TRUE | TRUE |
| _complex_view_merging | FALSE | TRUE | TRUE |
| _unnest_subquery | FALSE | TRUE | TRUE |
| _pred_move_around | FALSE | TRUE | TRUE |
| _remove_aggr_subquery | FALSE | FALSE | TRUE |
| _optimizer_squ_bottomup | FALSE | FALSE | TRUE |
| _push_join_predicate | FALSE | TRUE | TRUE |
| _push_join_union_view | FALSE | TRUE | TRUE |
| _push_join_union_view2 | FALSE | FALSE | TRUE |
| _optimizer_skip_scan_enabled | FALSE | TRUE | TRUE |
| _parallel_broadcast_enabled | FALSE | TRUE | TRUE |
| _right_outer_hash_enable | FALSE | FALSE | TRUE |
| skip_unusable_indexes | FALSE | FALSE | TRUE |
| _optimizer_dim_subq_join_sel | FALSE | FALSE | TRUE |
| _query_rewrite_setopgrw_enable | FALSE | FALSE | TRUE |
| _optimizer_join_order_control | 0 | 0 | 3 |
| _bloom_filter_enabled | FALSE | FALSE | TRUE |
| _gby_hash_aggregation_enabled | FALSE | FALSE | TRUE |
| _sql_model_unfold_forloops | COMPILE_TIME | COMPILE_TIME | RUN_TIME |
| _optimizer_transitivity_retain | FALSE | FALSE | TRUE |
| _px_pwg_enabled | FALSE | FALSE | TRUE |
| _optimizer_or_expansion | BREADTH | BREADTH | DEPTH |
| _selfjoin_mv_duplicates | FALSE | FALSE | TRUE |
| _dimension_skip_null | FALSE | FALSE | TRUE |
在10g中不能将Optimizer_features_enable设成10.2.0, 而9i中则可以不带第四个版本号.