Oracle 11g新特性-初始化文件创建（Memory）
Oracle 11g对于初始化增加了一个特别有用的功能，它可以根据内存中的参数设置来创建初始化参数文件。
Oracle从9i推出SPFILE之后，就给出了使用PFILE创建SPFILE以及由SPFILE创建PFILE的语法。
在Oracle 11g中，Oracle增强了这种语法，使得创建PFILE或SPFILE时，不在需要指定一个物理的文件，而是可以从当前内存中的设置来获取参数配置。
采用这种方式创建的PFILE或SPFILE，可以保证获得的参数就是当前运行的参数，而如果从PFILE或SPFILE则无法确保文件中的参数设置与数据库运行的参数设置一致。
语法很简单，将创建时的FROM语句后面的文件类型PFILE或SPFILE改为MEMORY就可以了。
[oracle@yangtk ~]$ sqlplus "/ as sysdba"
SQL*Plus: Release 11.1.0.6.0 - Production on Thu Jan 10 15:06:30 2008Copyright (c) 1982, 2007, Oracle. All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> create pfile='/home/oracle/initora11g_p.ora' from memory;
File created.
SQL> create spfile='/home/oracle/spfileora11g_p.ora' from memory;
File created.
注意：上面的这种方式要求数据库至少处于NOMOUNT状态，否则会出现报错：
SQL> shutdown immediate
Database closed.Database dismounted.ORACLE instance shut down.SQL> create pfile='/home/oracle/initora11g_p.ora' from memory;create pfile='/home/oracle/initora11g_p.ora' from memory*ERROR at line 1:ORA-00922: missing or invalid optionSQL> create spfile='/home/oracle/spfileora11g_p.ora' from memory;create spfile='/home/oracle/spfileora11g_p.ora' from memory*ERROR at line 1:ORA-00922: missing or invalid optionSQL> startup nomountORACLE instance started.Total System Global Area 267825152 bytesFixed Size 1299316 bytesVariable Size 176163980 bytesDatabase Buffers 88080384 bytesRedo Buffers 2281472 bytesSQL> create pfile='/home/oracle/initora11g_p.ora' from memory;File created.SQL> create spfile='/home/oracle/spfileora11g_p.ora' from memory;File created.
案例：
[root@rh6 ~]# su - oracle
[oracle@rh6 ~]$ export ORACLE_SID=test1
[oracle@rh6 ~]$ sqlplus '/as sysdba'SQL*Plus: Release 11.2.0.1.0 Production on Mon Feb 24 16:22:52 2014Copyright (c) 1982, 2009, Oracle. All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing options16:22:52 SYS@ test1 >create spfile='/home/oracle/spfiletest1.ora' from memory;File created.[oracle@rh6 ~]$ strings /home/oracle/spfiletest1.ora |more*.__db_cache_size=16M*.__java_pool_size=24M*.__large_pool_size=32M*.__oracle_base='/u01/app/oracle' # ORACLE_BASE set from environment*.__pga_aggregate_target=10M*.__sga_target=280M*.__shared_io_pool_size=0*.__shared_pool_size=128M*.__streams_pool_size=0*._aggregation_optimization_settings=0*._always_anti_join='CHOOSE'*._always_semi_join='CHOOSE'*._and_pruning_enabled=TRUE*._b_tree_bitmap_plans=TRUE*._bloom_filter_enabled=TRUE*._bloom_folding_enabled=TRUE*._bloom_pruning_enabled=TRUE*._complex_view_merging=TRUE*._compression_compatibility='11.2.0'*._connect_by_use_union_all='TRUE'*._convert_set_to_join=FALSE*._cost_equality_semi_join=TRUE*._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......以上为截取的部分spfile里的内容 。