查询oracle隐含参数

我都是放在$ORACLE_HOME/rdbms/admin下，看起来像个Oracle提供的脚本

$ cat show_para.sql

col p_name for a40

col p_DESCRIPTION for a50

col p_value for a30

set linesize 10000

SELECT i.ksppinm p_name,

i.ksppdesc p_description,

CV.ksppstvl p_VALUE,

CV.ksppstdf isdefault,

DECODE (BITAND (CV.ksppstvf, 7),1, 'MODIFIED',4, 'SYSTEM_MOD', 'FALSE')

ismodified,

DECODE (BITAND (CV.ksppstvf, 2), 2, 'TRUE', 'FALSE') isadjusted

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 upper(i.ksppinm) LIKE upper('%&p%')

ORDER BY REPLACE (i.ksppinm, '_', '');

比如我现在想查CBC Latch的数量，如下操作：

SQL*Plus: Release 11.2.0.1.0 Production on Sat Feb 16 18:51:17 2013

Copyright (c) 1982, 2009, Oracle. All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> @?/rdbms/admin/show_para　　--@代表运行，?代表$ORACLE_HOME

Enter value for p: latch --输入latch，如果不记得CBC Latch的参数，那就做糊涂查询

old 12: AND upper(i.ksppinm) LIKE upper('%&p%')

new 12: AND upper(i.ksppinm) LIKE upper('%latch%')

P_NAME P_DESCRIPTION P_VALUE ISDEFAULT ISMODIFIED ISADJ

---------------------------------------- -------------------------------------------------- ------------------------------ --------- ---------- -----

_cp_num_hash_latches connection pool number of hash latches 1 TRUE FALSE FALSE

_db_block_hash_latches Number of database block hash latches 4096 TRUE FALSE FALSE--这个参数就是CBC Latch

_db_block_lru_latches number of lru latches 16 　TRUE FALSE FALSE

_db_blocks_per_hash_latch Number of blocks per hash latch TRUE FALSE FALSE

_deq_ht_child_latches deq ht child latches 8 　　TRUE FALSE FALSE

_disable_latch_free_SCN_writes_via_32cas disable latch-free SCN writes using 32-bit compare FALSE TRUE FALSE FALSE

Oracle中有很多隐藏参数，一般不建议修改，默认值为佳。