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DBWR enhancements In Oracle10g
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$ksppcv y 6 where 7 x.inst_id = userenv('Instance') and 8 y.inst_id = userenv('Instance') and 9 x.indx = y.indx and 10 x.ksppinm like '%_dbwr_scan%' 11 /
KSPPINM KSPPDESC KSPPSTVL -------------------- ---------------------------------------- ---------- _dbwr_scan_interval dbwriter scan interval 10
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从Oracle10g开始,此缺省值被调这个为300 s:
SQL> select * from v$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
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在Oracle10gR2中,这个参数未作进一步调整,缺省值仍然为300:
SQL> select * from v$version 2 /
BANNER ---------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod PL/SQL Release 10.2.0.1.0 - Production CORE 10.2.0.1.0 Production TNS for Linux: Version 10.2.0.1.0 - Production NLSRTL Version 10.2.0.1.0 - Production
SQL> col ksppinm for a20 SQL> col ksppdesc for a40 SQL> col ksppstvl for a10 SQL> select 2 ksppinm,ksppdesc,ksppstvl 3 from 4 sys.x$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
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以上内容,仅供参考.
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By eygle on 2006-02-07 16:09 |
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