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1、建表方式Acreate table lx_bbk--tablespace test is a created by asm pattern.tablespace testasselect * from scott.emp;Create table(asm) 阅读全文
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Oracle 10g 11g New Features OverviesASM InstanceFlashback IFlashback IIFlashback DatabaseManaging MemoryAuto SchedularMaintaincePerformanceManage DB PerformanceSQL PerformanceDiag DatabaseMoving DataManage SpaceManage Databse SpaceDUP DatabaseSupport 阅读全文
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Table Lock ModesThese table lock modes are automatically assigned by the Oracle server:Row Exclusive(RX):INSERT,UPDATE,DELETERow Share(RS):SELECT ... FOR UPDATEManually Locking a TableManually acquired in LOCK TABLE StatementSQL>LOCK TABLE HR.employees IN share MODE;Share(S)No DML operations allo 阅读全文
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DML LocksA DML transaction gets at least two blocks:A shared table lockAn exclusive row lockA shared table lock主要是阻止DDL语句对当前表进行修改.An exclusive row lock主要是阻止别的transaction修改同一条记录.如何查看锁的信息?有三个重要的动态性能视图:v$transaction:记录了当前活动的transaction.desc v$transactionSQL> desc v$transaction; Name ... 阅读全文
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ObjectivesAfter completing this lesson,you should be able to do the following:Define levels of lockingIdentify causes of contentionPrevent locking problemsUse Oracle utilities to detect lock contentionResolve contention in an emergencyResovle deadlock conditionsModes of LockingOracle Database uses t 阅读全文
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Partition table 三种基本类型:ranage、hash、list partition table，另外composite partition就是对以上三种类型的组合类型.Composite PartitioningIdeal for both historical data and data placementProvides high availability and manageability,like range partitioningImproves performance for parallel DML and supports partition-wise joi 阅读全文
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Hash Partitioning OverviewEasy to ImplementEnables better performance for PDML and partion-wise joinsPDML->P DML并发的修改数据partition-wise join只能的Join,只需要有用的Partition 进行Join,没用的partition就不参加JoinInserts rows into partitions automatically based on the hash of the partion keySupports(hash) local indexesp 阅读全文
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Partitioning MethodsThe following partitioning methods are available:RangeHashListComposite按年度分区，2009年、2010年、...每年一张表；自oracle 9i以后，每个表空间可以指定不同的block_size，但是在分区表中，每个不同的分区必须使用相同的db_block_size;CREATE TABLE sales( acct_no NUMBER(5), person VARCHAR2(30), sales_amount... 阅读全文
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Hash Clustered TablesHash Clustered Table的设计目的就是减少I/O的次数，如果设计不当（一般因为size大小设置问题） 导致overflow blocks ,无疑会增大I/O的次数，造成事倍功半.create hash clustered table and show it space info[oracle@arcerzhang usefull_scripts]$ lltotal 4-rw-r--r-- 1 oracle oinstall 3642 May 9 12:45 show_space.sql[oracle@arcerzhang useful. 阅读全文
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Data Access MethodsTo enhance performance ,you can use the following data access methods:ClustersIndexesB-tree(nomal or reverse key)BitmapFunction basedIndex-organized tablesMaterialized viewsClustersCluster TypesHash Clustered TablesExample创建Index ClusterCREATE CLUSTER mycluster(deptno number(2)) s 阅读全文