oracleparameter

概述

Oracle系统中有一类参数称之为隐藏参数，是系统中使用，但Oracle官方没有公布的参数， 11g中共有2562 左右隐藏参数，这些参数可能是那些还没有成熟或者是系统开发中使用的参数。这些参数在所有Oracle官方提供的文档中都没有介绍，他们的命名有一个共同特征就是都以 '_' 作为参数的首字符。当然这部分的参数是不建议用户进行修改的，除非你对ORACLE 的整体架构相当熟悉，对整个参数修改所带来的影响有个清晰的认识。

如：查看_optimizer_adaptive_cursor_sharing

SELECT i.ksppinm name, i.ksppdesc description, CV.ksppstvl VALUE, CV.ksppstdf isdefault FROM sys.x$ksppi i, sys.x$ksppcv CV WHERE i.inst_id = USERENV ('Instance') AND CV.inst_id = USERENV ('Instance') AND i.indx = CV.indx AND i.ksppinm ='_optimizer_adaptive_cursor_sharing'ORDER BY REPLACE (i.ksppinm, '_', '');11G常见的隐藏参数说明ORACLE 11GR2常用参数(含隐含参数)设置如下：

alter system t "_PX_u_large_pool" = true scope=spfile;alter system t "_clusterwide_global_transactions" = fal scope=spfile;alter system t "_gc_defer_time" = 3 scope=spfile;alter system t "_resource_manager_always_off" = true scope=spfile;alter system t "_resource_manager_always_on" = fal scope=spfile;alter system t "_rial_direct_read" = never scope=spfile;alter system t "_cleanup_rollback_entries" = 400 scope=spfile;alter system t "_optimizer_u_feedback" = fal scope=spfile;alter system t "_dbms_sql_curity_level" =0 scope=spfile;alter system t "_bloom_pruning_enabled" = fal scope=spfile;alter system t "_gc_policy_time" = 0 scope=spfile;alter system t "_bloom_filter_enabled" = fal scope=spfile;alter system t "_gc_read_mostly_locking" = fal scope=spfile;alter system t "_gc_undo_affinity" = fal scope=spfile;alter system t "_smu_debug_mode" = 134217728 scope=spfile;alter system t "_undo_autotune" = fal scope=spfile;alter system t deferred_gment_creation = fal scope=spfile;alter system t Audit_trail = none scope=spfile;alter system t event='28401 trace name context forever,level 1' scope=spfile;alter system t "_optimizer_extended_cursor_sharing_rel"=none;alter system t "_optimizer_extended_cursor_sharing"=none;alter system t "_optimizer_adaptive_cursor_sharing"=fal;

篇幅有限，Oracle隐藏参数就介绍到这了，大家感兴趣的话也可以测试研究一下。后面小编会分享更多DBA方面的内容，感兴趣的朋友走一波关注哩~