oracleparameter

概述

Oracle系統中有一類參數稱之為隱藏參數，是系統中使用，但Oracle官方沒有公布的參數， 11g中共有2562 左右隱藏參數，這些參數可能是那些還沒有成熟或者是系統開發中使用的參數。這些參數在所有Oracle官方提供的文檔中都沒有介紹，他們的命名有一個共同特征就是都以 '_' 作為參數的首字符。當然這部分的參數是不建議用戶進行修改的，除非你對ORACLE 的整體架構相當熟悉，對整個參數修改所帶來的影響有個清晰的認識。

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常見的隱藏參數說明ORACLE 11GR2常用參數(含隱含參數)設置如下：

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隱藏參數就介紹到這了，大家感興趣的話也可以測試研究一下。后面小編會分享更多DBA方面的內容，感興趣的朋友走一波關注哩~