DRM原理、管理与相关隐藏参数

DRM是Oracle RAC架构中提供的动态重新定义数据块的master节点，使得频繁访问数据块的节点成为Master节点从而减少CacheFusion，数据库传播的开销，下面我们  

判断是否启动DRM特性

col KSPPINM for a30

col KSPPSTVL for a30

col KSPPDESC for a50

set line 200

SELECT   ksppinm, ksppstvl, ksppdesc FROM   x$ksppi x, x$ksppcv y WHERE   x.indx = y.indx AND  ksppinm ='_gc_read_mostly_locking';

KSPPINM                        KSPPSTVL                       KSPPDESC

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

_gc_read_mostly_locking        TRUE                           if TRUE, enable read-mostly locking

SELECT   ksppinm, ksppstvl, ksppdesc FROM   x$ksppi x, x$ksppcv y WHERE   x.indx = y.indx AND  ksppinm ='_gc_bypass_readers';

KSPPINM                        KSPPSTVL                       KSPPDESC

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

_gc_bypass_readers             TRUE                           if TRUE, modifications bypass readers

SELECT   ksppinm, ksppstvl, ksppdesc FROM   x$ksppi x, x$ksppcv y WHERE   x.indx = y.indx AND  ksppinm='_gc_policy_time';

SQL> SELECT   ksppinm, ksppstvl, ksppdesc FROM   x$ksppi x, x$ksppcv y WHERE   x.indx = y.indx AND  ksppinm='_gc_policy_time';

KSPPINM                        KSPPSTVL                       KSPPDESC

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

_gc_policy_time                10                             how often to make object policy decisions in minutes

禁用DRM特性

alter system set  "_gc_read_mostly_locking"=false scope=spfile;

alter system set  "_gc_bypass_readers"=false scope=spfile;

或者

alter system set "_gc_policy_time=0"  scope=spfile;

SELECT   ksppinm, ksppstvl, ksppdesc FROM   x$ksppi x, x$ksppcv y WHERE   x.indx = y.indx AND  ksppinm='_gc_policy_time';

查询buffer在数据库缓冲区中的CR块copy数量

col KSPPINM for a30

col KSPPSTVL for a30

col KSPPDESC for a50

set line 200

SELECT   ksppinm, ksppstvl, ksppdesc FROM   x$ksppi x, x$ksppcv y

 WHERE   x.indx = y.indx AND  ksppinm='_db_block_max_cr_dba';

DRM发生条件的几个隐藏参数

col KSPPINM for a30

col KSPPSTVL for a30

col KSPPDESC for a60

set line 200

SELECT   ksppinm, ksppstvl, ksppdesc  FROM   x$ksppi x, x$ksppcv y  WHERE   x.indx = y.indx AND  ksppinm='_gc_policy_time'

union all

SELECT   ksppinm, ksppstvl, ksppdesc  FROM   x$ksppi x, x$ksppcv y  WHERE   x.indx = y.indx AND  ksppinm='_gc_policy_minimum'

union all

SELECT   ksppinm, ksppstvl, ksppdesc  FROM   x$ksppi x, x$ksppcv y  WHERE   x.indx = y.indx AND  ksppinm='_gc_affinity_ratio';

KSPPINM                        KSPPSTVL                       KSPPDESC

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

_gc_policy_time                10                                how often to make object policy decisions in minutes

_gc_policy_minimum      1500                           dynamic object policy minimum activity per minute

_gc_affinity_ratio             50                               dynamic object affinity ratio