Oracle 11g新特性:spfile Fault-tolerant增强

作者：盖国强 来源:eygle.com

在以前的版本中，如果spfile参数文件丢失，我们只能通过备份去恢复，或者从存在的pfile中创建...

实际上如果仅仅是参数文件丢失，数据库仍然在运行，那我们完全可以从数据库实例中得到当前的所有运行参数，从Oracle 11g开始，一个新的命令被引入，这个命令是：
create spfile from memory;

这个命令可以使用当前的参数设置在缺省位置创建一个spfile文件，当然我们也可以指定一个不同的位置：

SQL> create spfile='/tmp/spfile.ora' from memory;

File created.

这一增强简化了我们在某些条件下的参数文件恢复，使得参数文件的可用性进一步提高。
不要不相信，参数文件特别是spfile文件损坏的情况非常常见，我自己也遭遇过一次。

当然创建出来的参数文件比现有的文件包含了更多的参数：

[oracle@test126 ~]$ strings /tmp/spfile.ora
*.__db_cache_size=184M
*.__java_pool_size=4M
*.__large_pool_size=4M
*.__oracle_base='/opt/oracle' # ORACLE_BASE set from environment
*.__pga_aggregate_target=92M
*.__sga_target=284M
*.__shared_io_pool_size=0
*.__shared_pool_size=84M
*.__streams_pool_size=0
*._always_anti_join='CHOOSE'
*._always_semi_join='CHOOSE'
*._b_tree_bitmap_plans=TRUE
*._bloom_filter_enabled=TRUE
*._bloom_pruning_enabled=TRUE
*._complex_view_merging=TRUE
*._convert_set_to_join=FALSE
*._cost_equality_semi_join=T
*._cpu_to_io=0
*._dimension_skip_null=TRUE
*._eliminate_common_subexpr=TRUE
*._enable_type_dep_selectivity=TRUE
*._fast_full_scan_enabled=TRUE
*._first_k_rows_dynamic_proration=TRUE
*._gby_hash_aggregation_enabled=TRUE
*._generalized_pruning_enabled=TRUE
*._globalindex_pnum_filter_enabled=TRUE
*._gs_anti_semi_join_allowed=TRUE
*._improved_outerjoin_card=TRUE
*._improved_row_length_enabled=TRUE
*._index_join_enabled=TRUE
*._ksb_restart_policy_times='0'
*._ksb_restart_policy_times='60'
*._ksb_restart_policy_times='120'
*._ksb_restart_policy_times='240' # internal update to set default
*._left_nested_loops_random=TRUE
*._local_communication_costing_enabled=TRUE
*._minimal_stats_aggregation=TRUE
*._mmv_query_rewrite_enabled=TRUE
*._new_initial_join_orders=TRUE
*._new_sort_cost_estimate=TRUE
*._nlj_batching_enabled=1
*._optim_adjust_for_part_skews=TRUE
*._optim_enhance_nnull_detection=TRUE
*._optim_new_default_join_sel=TRUE
*._optim_peek_user_binds=TRUE
*._optimizer_adaptive_cursor_sharing=TRUE
*._optimizer_better_inlist_costing='ALL'
*._optimizer_cbqt_no_size_restriction=TRUE
*._optimizer_complex_pred_selectivity=TRUE
*._optimizer_compute_index_stats=TRUE
*._optimizer_connect_by_combine_sw=TRUE
*._optimizer_connect_by_cost_based=TRUE
*._optimizer_correct_sq_selectivity=TRUE
*._optimizer_cost_based_transformation='LINEAR'
*._optimizer_cost_hjsmj_multimatch=TRUE
*._optimizer_cost_model='CHOOSE'
*._optimizer_dim_subq_join_sel=TRUE
*._optimizer_distinct_elimination=TRUE
*._optimizer_enable_density_improvements=TRUE
*._optimizer_enable_extended_stats=TRUE
*._optimizer_enhanced_filter_push=TRUE
*._optimizer_extend_jppd_view_types=TRUE
*._optimizer_extended_cursor_sharing='UDO'
*._optimizer_extended_cursor_sharing_rel='SIMPLE'
*._optimizer_extended_stats_usage_control=240
*._optimizer_filter_pred_pullup=TRUE
*._optimizer_fkr_index_cost_bias=10
*._optimizer_group_by_placement=TRUE
*._optimizer_improve_selectivity=TRUE
*._optimizer_join_elimination_enabled=TRUE
*._optimizer_join_order_control=3
*._optimizer_join_sel_sanity_check=TRUE
*._optimizer_max_permutations=2000
*._optimizer_mode_force=TRUE
*._optimizer_multi_level_push_pred=TRUE
*._optimizer_native_full_outer_join='FORCE'
*._optimizer_new_join_card_computation=TRUE
*._optimizer_null_aware_antijoin=TRUE
*._optimizer_or_expansion='DEPTH'
*._optimizer_order_by_elimination_enabled=TRUE
*._optimizer_outer_to_anti_enabled=TRUE
*._optimizer_push_down_distinct=0
*._optimizer_push_pred_cost_based=TRUE
*._optimizer_rownum_bind_default=10
*._optimizer_rownum_pred_based_fkr=TRUE
*._optimizer_skip_scan_enabled=TRUE
*._optimizer_sortmerge_join_inequality=TRUE
*._optimizer_squ_bottomup=TRUE
*._optimizer_star_tran_in_with_clause=TRUE
*._optimizer_system_stats_usage=TRUE
*._optimizer_transitivity_retain=TRUE
*._optimizer_undo_cost_change='11.1.0.6'
*._or_expand_nvl_predicate=TRUE
*._ordered_nested_loop=TRUE
*._parallel_broadcast_enabled=TRUE
_partition_view_enabled=TRUE
*._pivot_implementation_method='CHOOSE'
*._pre_rewrite_push_pred=TRUE
*._pred_move_around=TRUE
*._push_join_predicate=TRUE
*._push_join_union_view=TRUE
*._push_join_union_view2=TRUE
*._px_minus_intersect=TRUE
*._px_pwg_enabled=TRUE
*._px_ual_serial_input=TRUE
*._query_rewrite_setopgrw_enable=TRUE
*._remove_aggr_subquery=TRUE
*._right_outer_hash_enable=TRUE
*._selfjoin_mv_duplicates=TRUE
*._sql_model_unfold_forloops='RUN_TIME'
*._sqltune_category_parsed='DEFAULT' # parsed sqltune_category
*._subquery_pruning_enabled=TRUE
*._subquery_pruning_mv_enabled=FALSE
*._table_scan_cost_plus_one=TRUE
*._union_rewrite_for_gs='YES_GSET_MVS'
*._unnest_subquery=TRUE
*._use_column_stats_for_function=TRUE
*.audit_file_dest='/opt/oracle/admin/dodd/adump'
*.audit_trail='DB'
*.compatible='11.1.0.0.0'
*.control_files='/opt/oracle/oradata/dodd/control01.ctl'
*.control_files='/opt/oracle/oradata/dodd/control02.ctl'
*.control_files='/opt/oracle/oradata/dodd/control03.ctl'
*.core_dump_dest='/opt/oracle/diag/rdbms/dodd/dodd/cdump'
*.db_block_size=8192
*.db_domain=''
*.db_name='dodd'
*.db_recovery_file_dest='/opt/oracle/flash_recovery_area'
*.db_recovery_file_dest_size=2G
*.diagnostic_dest='/opt/oracle'
*.log_buffer=6000640 # log buffer update
*.memory_target=376M
*.open_cursors=300
*.optimizer_dynamic_sampling=2
*.optimizer_mode='ALL_ROWS'
*.plsql_warnings='DISABLE:ALL' # PL/SQL warnings at init.ora
*.processes=150
*.query_rewrite_enabled='TRUE'
*.remote_login_passwordfile='EXCLUSIVE'
*.resource_manager_plan=''
*.result_cache_max_size=992K
*.skip_unusable_indexes=TRUE
*.undo_tablespace='UNDOTBS1'