为了避免DBWR不必要的唤醒及过于活跃,从Oracle10g开始,Oracle对DBWR的SCAN间隔进行了调整.
在内部由一个隐含参数:_dbwr_scan_interval 控制.
Oracle9i中这个参数缺省值为10 s:
SQL> select * from v$version
2 /
BANNER
----------------------------------------------------------------
Oracle9i Enterprise Edition Release 9.2.0.4.0 - 64bit Production
PL/SQL Release 9.2.0.4.0 - Production
CORE 9.2.0.3.0 Production
TNS for Solaris: Version 9.2.0.4.0 - Production
NLSRTL Version 9.2.0.4.0 - Production
SQL> col ksppinm for a20
SQL> col ksppdesc for a40
SQL> col ksppstvl for a10
SQL> select
2 ksppinm,ksppdesc,ksppstvl
3 from
4 sys.x$ksppi x,
5 sys.x$ksppcv y
6 where
7 x.inst_id = userenv('Instance') and
8 y.inst_id = userenv('Instance') and
9 x.indx = y.indx and
10 x.ksppinm like '%_dbwr_scan%'
11 /
KSPPINM KSPPDESC KSPPSTVL
-------------------- ---------------------------------------- ----------
_dbwr_scan_interval dbwriter scan interval 10
|
从Oracle10g开始,此缺省值被调这个为300 s:
SQL> select * from v$version
2 /
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.1.0.3.0 - 64bi
PL/SQL Release 10.1.0.3.0 - Production
CORE 10.1.0.3.0 Production
TNS for Solaris: Version 10.1.0.3.0 - Production
NLSRTL Version 10.1.0.3.0 - Production
SQL> col ksppinm for a20
SQL> col ksppdesc for a40
SQL> col ksppstvl for a10
SQL> select
2 ksppinm,ksppdesc,ksppstvl
3 from
4 sys.x$ksppi x,
5 sys.x$ksppcv y
6 where
7 x.inst_id = userenv('Instance') and
8 y.inst_id = userenv('Instance') and
9 x.indx = y.indx and
10 x.ksppinm like '%_dbwr_scan%'
11 /
KSPPINM KSPPDESC KSPPSTVL
-------------------- ---------------------------------------- ----------
_dbwr_scan_interval dbwriter scan interval 300
|
