ArcerZhang`s Technology Blog

摘要： 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

摘要： 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

摘要： 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

摘要： 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

摘要： 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

摘要： 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

摘要： 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

摘要： 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

摘要： 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

摘要： 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