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To move or copy a set of tablespaces, you must make the tablespaces read only, copy the datafiles of these tablespaces, and use export/import to move the database information (metadata) stored in the data dictionary. Both the datafiles and the metadata export file must be copied to the target database. The transport of these files can be done using any facility for copying flat files, such as the operating system copying facility, ftp, or publishing on CDs. After copying the datafiles and import

A tablespace repository is a collection of tablespace sets. Tablespace repositories are built on file group repositories, but tablespace repositories only contain the files required to move or copy tablespaces between databases. Different tablespace sets may be stored in a tablespace repository, and different versions of a particular tablespace set also may be stored. A version of a tablespace set in a tablespace repository consists of the following files:■ The Data Pump export dump file for th

A transportable tablespace lets you move a subset of an Oracle database from one Oracle database to another, even across different platforms. You can clone a tablespace and plug it into another database, copying the tablespace between databases, or you can unplug a tablespace from one Oracle database and plug it into another Oracle database, moving the tablespace between databases. Moving data by transporting tablespaces can be orders of magnitude faster than either export/import or unload/load

One or more temporary tablespaces can be used only for sort segments. A temporary tablespace is not the same as a tablespace that a user designates for temporary segments, which can be any tablespace available to the user. No permanent schema objects can reside in a temporary tablespace. Sort segments are used when a segment is shared by multiple sort operations. One sort segment exists for every instance that performs a sort operation in a given tablespace.Temporary tablespaces provide performa

You can manage space for sort operations more efficiently by designating one or more temporary tablespaces exclusively for sorts. Doing so effectively eliminates serialization of space management operations involved in the allocation and deallocation of sort space. A single SQL operation can use more than one temporary tablespace for sorting. For example, you can create indexes on very large tables, and the sort operation during index creation can be distributed across multiple tablespaces.All o

The primary purpose of read-only tablespaces is to eliminate the need to perform backup and recovery of large, static portions of a database. Oracle never updates the files of a read-only tablespace, and therefore the files can reside on read-only media such as CD-ROMs or WORM drives. Read-only tablespaces cannot be modified. To update a read-only tablespace, first make the tablespace read/write. After updating the tablespace, you can then reset it to be read only.Because read-only tablespaces c

When a tablespace goes offline, Oracle does not permit any subsequent SQL statements to reference objects contained in that tablespace. Active transactions with completed statements that refer to data in that tablespace are not affected at the transaction level. Oracle saves rollback data corresponding to those completed statements in a deferred rollback segment in the SYSTEM tablespace. When the tablespace is brought back online, Oracle applies the rollback data to the tablespace, if needed. Wh

A database administrator can bring any tablespace other than the SYSTEM tablespace online (accessible) or offline (not accessible) whenever the database is open. The SYSTEM tablespace is always online when the database is open because the data dictionary must always be available to Oracle.A tablespace is usually online so that the data contained within it is available to database users. However, the database administrator can take a tablespace offline for maintenance or backup and recovery purpo

Oracle supports multiple block sizes in a database. The standard block size is used for the SYSTEM tablespace. This is set when the database is created and can be any valid size. You specify the standard block size by setting the initialization parameter DB_BLOCK_SIZE. Legitimate values are from 2K to 32K.In the initialization parameter file or server parameter, you can configure subcaches within the buffer cache for each of these block sizes. Subcaches can also be configured while an instance i

baidu了一下关于日出时间早晚的比较可以分为四类：1、在同一纬度上的两地，越东边的地点越先看到日出（不考虑地形因素的影响）；2、在同一经度上的两地，白昼越长的地点越先看到日出（不考虑地形因素的影响）；3、在同一地点，海拔越高的地方越先看到日出；4、在经度和纬度均不相同的地点，如果两地经度相差较小，一般为白昼越长的地点越先看到日出。如果两地经度相差较大，既要考虑白昼长短的因素，又要考虑经度差的因素。所以应该是和纬度经度海拔有关......[@more@]

1. 将administrator用户踢出ora_dba组2. 修改ORACLE_HOME/network/admin/sqlnet.ora将SQLNET.AUTHENTICATION_SERVICES= (nts) 屏蔽或者改为none.两者择其一 ， 就可以禁用windows本地认证 , 从而sys输入正确的密码才能登入.[@more@]

If you created your database with an earlier version of Oracle, then you could be usingdictionary managed tablespaces. For a tablespace that uses the data dictionary tomanage its extents, Oracle updates the appropriate tables in the data dictionarywhenever an extent is allocated or freed for reuse. Oracle also stores rollbackinformation about each update of the dictionary tables. Because dictionary tables androllback segments are part of the database, the space that they occupy is subject to the

When you create a locally managed tablespace using the CREATE TABLESPACEstatement, the SEGMENT SPACE MANAGEMENT clause lets you specify how free andused space within a segment is to be managed. Your choices are:1 AUTOThis keyword tells Oracle that you want to use bitmaps to manage the free spacewithin segments. A bitmap, in this case, is a map that describes the status of eachdata block within a segment with respect to the amount of space in the blockavailable for inserting rows. As more or l

A tablespace that manages its own extents maintains a bitmap in each datafile to keeptrack of the free or used status of blocks in that datafile. Each bit in the bitmapcorresponds to a block or a group of blocks. When an extent is allocated or freed forreuse, Oracle changes the bitmap values to show the new status of the blocks. Thesechanges do not generate rollback information because they do not update tables in thedata dictionary (except for special cases such as tablespace quota information)

Tablespaces allocate space in extents. Tablespaces can use two different methods tokeep track of their free and used space:1 Locally managed tablespaces: Extent management by the tablespace2 Dictionary managed tablespaces: Extent management by the data dictionaryWhen you create a tablespace, you choose one of these methods of space management.Later, you can change the management method with the DBMS_SPACE_ADMINPL/SQL package.If you do not specify extent management when you create atablespa

秒 s - second厘秒 cs - centisecond - 100th of a second 毫秒 ms - millisecond - 1000th of a second微秒 us - microsecond - 1000000th of a second[@more@]

NAMES.DIRECTORY_PATHUse the parameter NAMES.DIRECTORY_PATH to specify the order of the namingmethods used for client name resolution lookups.<naming method value> : <description>tnsnames (local naming naming method) : Set to resolve a net service name through the tnsnames.orafile on the client.ldap (directory naming naming method) : Set to resolve a database service name, net service name, ornet　service alias through a directory server.ezconnect or hostname (easy connect naming

SQLNET.AUTHENTICATION_SERVICESUse the parameter SQLNET.AUTHENTICATION_SERVICES to enable one or moreauthentication services. If authentication has been installed, it is recommended thatthis parameter be set to either none or to one of the authentication methods.Authentication Methods Available with Oracle Net Services:1 none for no authentication methods. A valid username and password can be usedto access the database.2 all for all authentication methods3 nts for Windows NT native authe

1 Create new tablespaces2 Add datafiles to tablespaces3 Set and alter default segment storage settings for segments created in atablespace4 Make a tablespace read only or read/write5 Make a tablespace temporary or permanent6 Rename tablespaces7 Drop tablespacesDBA可对表空间进行如下操作:1. 创建新的表空间2. 为表空间增加数据文件3. 为表空间设置或更改段的存储设置4. 可使表空间只读 ， 可读可写5. 设置表空间为临时或者永久6. 为表空间重命名7. 删除表空间[@more@]

1 Control disk space allocation for database data2 Assign specific space quotas for database users3 Control availability of data by taking individual tablespaces online oroffline4 Perform partial database backup or recovery operations5 Allocate data storage across devices to improve performance使用多重表空间 ， 可进行如下任务1. 控制磁盘空间的分配2. 为数据库用户分配指定的磁盘空间额度3. 控制数据的可用性 ，是某个表空间联机或脱机4. 进行备份恢复操作5. 通过设备控制数据的存储 ，