Qdblinxi的博客

主备切换前，一定要注意日志全都应用主备切换报错，如何切换回去？现备库（原主库）切回主库QL> select database_role,switchover_status from v$database;DATABASE_ROLESWITCHOVER_STATUSPHYSICAL STANDBYSESSIONS ACTIVESQL> alter database commit to switchover to primary with session shutdown;Da

1.在经过主库rman duplicate 复制后，备库启动时报错ERROR at line 1:ORA-10458: standby database requires recoveryORA-01152: file 1 was not restored from a sufficiently old backupORA-01110: data file 1: ‘/opt/oracle/oradata/yoon/system01.dbf’此情况多为tnsname.ora配置问题;或者主库重启即可

统计某个表所占空间，统计索引将table 改为INDEXselect segment_name, sum(bytes)/1024/1024/1024 GB from user_segments where segment_type=‘TABLE’ and segment_name in (‘APPLYCONSTRAINTCOLUMNS′,′ACCESS_CONSTRAINT_COLUMNS','ACCESSC​ONSTRAINTC​OLUMNS′,′ACCESS’) group by segment_

https://blog.youkuaiyun.com/ly7472712/article/details/111186830?spm=1001.2014.3001.5501集群https://blog.youkuaiyun.com/ly7472712/article/details/110491656?spm=1001.2014.3001.5501单实例

OGG-01027WARNING OGG-01027 Long Running Transaction: XID 82.4.242063, Items 0, Extract YX_EXT1, Redo Thread 1, SCN 2379.2132775890 (10219859973074), Redo Seq #5688, Redo RBA 195997712. 查看是否有长交易，里面的xid与告警日志对应，通过xid找到sql_textsend extract (进程名)，show

动态采样有0-10 共11个level,级别越大，扫描的rows块越多。动态采样的标志为dynamic sampling …,在olap数据仓库环境下，level级别一般设置为3、4，oltp中一般不使用动态采样。@在统计信息失效的情况下，即state为yes时，执行计划中会出现dynamic sampling…@当表中含有临时表，临时表不会被列为动态采样对象。----如何修改采样级别？show parameter optimizer_dynamic_sampling，可改此参数。alter ses

锁，在数据库的发生来源于并发。通常通过视图vlock查看。selectsid,type,id1,id2,lmode,request,blockfromvlock查看。select sid ,type,id1,id2,lmode,request,block from vlock查看。selectsid,type,id1,id2,lmode,request,blockfromvlock where sid in (1,2) order by sid;其中，block=1表示此花花正在阻塞其他的会话，requ

集群dbca -silent -createDatabase -templateName General_Purpose.dbc -gbName ra -sid ra -sysPassword a -systemPassword a -storeageType ASM -diskGroupName DATADG -datafileJarLocation $ORACLE_HOME/assistants/dbca/templates nodeinfo rac1,rac2 -characterset ZHS16

将磁盘挂载到/u01下装盘Cfgmgr识别盘Lspv列出当前系统可用的磁盘Chdev -l hdisk5 -a pv=yes加新盘新建卷组oraclevg （新建卷组需要激活，varyonvg oraclevg）mkvg -y oraclevg hdisk5 新命名为oraclevg逻辑卷组mklv -y oraclelv oraclevg hdisk5 新命名为oraclelv 逻辑卷若已有物理卷oraclevg则，执行extendvg oraclevg hdisk56.

awr报告无snap_id

数据库表空间文件不小心放错了位置，如何更改？

1.内连接：inner join 查询两个表中相同的所有行,左、右连接#的交集。2.左连接：A left join B on (A. =B. )，以A表为主，A表有，B表无加null3.右连接：A right join B on (A. =B. )，以B表为主， B表有，A表无加null4.完全连接： A full join B on (A. =B. ),A表有，B表无加null,B表有，A表无加null ,左、右连接的并集。5.外连接：左外连接：(A left outer join B)