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If you are currently using a text initialization parameter file, use the following steps to migrate to a server parameter file.1. If the initialization parameter file is located on a client machine, transfer the file (for example, FTP) from the client machine to the server machine. 2. Create a server parameter file using the CREATE SPFILE statement. This statement reads the initialization parameter file to create a server parameter file. The database does not have to be started to issue a CREATE

A server parameter file can be thought of as a repository for initialization parameters that is maintained on the machine running the Oracle Database server. It is, by design, a server-side initialization parameter file. Initialization parameters stored in a server parameter file are persistent, in that any changes made to the parameters while an instance is running can persist across instance shutdown and startup. This arrangement eliminates the need to manually update initialization parameters

Parallel execution dramatically reduces response time for data-intensive operations on large databases typically associated with decision support systems and data warehouses. In addition to conventional tables, you can use parallel query and parallel DML with range- and hash-partitioned tables. By doing so, you can enhance scalability and performance for batch operations.The semantics and restrictions for parallel DML sessions are the same whether you are using index-organized tables or not.[@mo

A partition-wise join is a join optimization for joining two tables that are both partitioned along the join column(s). With partition-wise joins, the join operation is broken into smaller joins that are performed sequentially or in parallel. Another way of looking at partition-wise joins is that they minimize the amount of data exchanged among parallel slaves during the execution of parallel joins by taking into account data distribution.[@more@]

The Oracle database server explicitly recognizes partitions and subpartitions. It then optimizes SQL statements to mark the partitions or subpartitions that need to be accessed and eliminates (prunes) unnecessary partitions or subpartitions from access by those SQL statements. In other words, partition pruning is the skipping of unnecessary index and data partitions or subpartitions in a query.For each SQL statement, depending on the selection criteria specified, unneeded partitions or subpartit

索引的选择性是指索引列中不同值的数目与表中记录数的比。如果一个表中有2000条记录，表索引列有1980个不同的值，那么这个索引的选择性就是1980/2000=0.99。　　一个索引的选择性越接近于1，这个索引的效率就越高。　　如果是使用基于cost的最优化，优化器不应该使用选择性不好的索引。如果是使用基于rule的最优化，优化器在确定执行路径时不会考虑索引的选择性（除非是唯一性索引），并且不得不手工优化查询以避免使用非选择性的索引。　　确定索引的选择性，可以有两种方法：手工测量和自动测量。　　（1）手工测量索引的选择性 　　如果

明明知道一件事情的成功几率很小，但是还是有人去试，这是一种什么心态？1 顽固执拗,执迷不悟,不见棺材不落泪,不撞南墙不回头2 自负（碍于面子）3 不懂得变通4 认为坚持一下就好了5 屡败屡战6 赌博心态7 还是其他[@more@]

Here are a few points to remember when using partitioned indexes on composite partitions:■ Subpartitioned indexes are always local and stored with the table subpartition by default.■ Tablespaces can be specified at either index or index subpartition levels.当在复合分区上使用分区索引时，需要记录以下几点：1. 子分区索引通常情况下为本地索引，并存储于表的子分区2. 表空间可以在索引或索引子分区级别指定[@more@]

Here are a few guidelines for data warehousing and DSS applications:■ Local indexes are preferable because they are easier to manage during data loads and during partition-maintenance operations.■ Local indexes can improve performance because many index partitions can be scanned in parallel by range queries on the index key.在数据载入和分区维护操作情况较多的情况下，本地索引更加合适在索引键的范围内查询时，本地索引可改进性能，因为许多索引分区能被并行扫描[@more@]

Here are a few guidelines for OLTP applications:■ Global indexes and unique, local indexes provide better performance than nonunique local indexes because they minimize the number of index partition probes.■ Local indexes offer better availability when there are partition or subpartition maintenance operations on the table.■ Hash-partitioned global indexes offer better performance by spreading out contention when the index is monotonically growing. In other words, most of the index insertions

You can create bitmap indexes on partitioned tables, with the restriction that the bitmap indexes must be local to the partitioned table. They cannot be global indexes.Global indexes can be unique. Local indexes can only be unique if the partitioning key is a part of the index key.可在分区表上创建位图索引，但必须是Local类型[@more@]

Global nonpartitioned indexes behave just like a nonpartitioned index. They are commonly used in OLTP environments and offer efficient access to any individual record.全局非分区索引普遍用于OLTP环境[@more@]

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Syntax LOG_FILE_NAME_CONVERT = 'string1' , 'string2' , 'string3' , 'string4' , ... Where: ■ string1 is the pattern of the primary database filename ■ string2 is the pattern of the standby database filename ■ string3 is the pattern of the primary database filename ■ string4 is the pattern of the standby database filename You can use as many pairs of primary and standby replacement

Syntax DB_FILE_NAME_CONVERT = 'string1' , 'string2' , 'string3' , 'string4' , ... Where: ■ string1 is the pattern of the primary database filename ■ string2 is the pattern of the standby database filename ■ string3 is the pattern of the primary database filename ■ string4 is the pattern of the standby database filename You can use as many pairs of primary and standby replacement

By default, the following operations on partitions on a heap-organized table mark all global indexes as unusable:ADD (HASH) COALESCE (HASH) DROP EXCHANGE MERGE MOVE SPLIT TRUNCATE These indexes can be maintained by appending the clause UPDATE INDEXES to the SQL statements for the operation. The two advantages to maintaining global indexes:■ The index remains available and online throughout the operation. Hence no other applications are affected by this operation.■ The index doesn't have to be

Global hash partitioned indexes improve performance by spreading out contention when the index is monotonically growing. In other words, most of the index insertions occur only on the right edge of an index.[@more@]

Global range partitioned indexes are flexible in that the degree of partitioning and the partitioning key are independent from the table's partitioning method. They are commonly used for OLTP environments and offer efficient access to any individual record.The highest partition of a global index must have a partition bound, all of whose values are MAXVALUE. This ensures that all rows in the underlying table can be represented in the index. Global prefixed indexes can be unique or nonunique.You c

Local partitioned indexes are easier to manage than other types of partitioned indexes. They also offer greater availability and are common in DSS environments. The reason for this is equipartitioning: each partition of a local index is associated with exactly one partition of the table. This enables Oracle to automatically keep the index partitions in sync with the table partitions, and makes each table-index pair independent. Any actions that make one partition's data invalid or unavailable on