##在这种模式下，数据库记录用于实例和介质恢复所需的所有日志。如果数据库处于归档模式下，你可以把日志归档到磁带上。如果数据库处于非归档模式，那么你能够进行实例恢复，但是不能够进行介质恢复。

Direct-Path INSERT without Logging

In this mode, Oracle Database inserts data without redo or undo logging. Instead, the database logs a small number of block range invalidation redo records and periodically updates the control file with information about the most recent direct write.

##在这种模式下，数据库不记录数据插入时的redo和undo日志，但在新区标记invalid状态和修改数据字典的时候会产生少量日志，并且定期的在控制文件中更新当前的direct write信息

Direct-path INSERT without logging improves performance. However, if you subsequently must perform media recovery, the invalidation redo records mark a range of blocks as logically corrupt, because no redo data was logged for them. Therefore, it is important that you back up the data after such an insert operation.

##Direct-path INSERT without logging能够提高性能。然后如果你随后就进行介质恢复，那些被标记为invalid状态的块会报逻辑错误，因为没有为这些块记录日志。因此在直接路径之后进行数据备份是很有必要的。

Beginning with release 11.2.0.2 of Oracle Database, you can significantly improve the performance of unrecoverable direct path inserts by disabling the periodic update of the control files. You do so by setting the initialization parameterDB_UNRECOVERABLE_SCN_TRACKING to FALSE. However, if you perform an unrecoverable direct path insert with these control file updates disabled, you will no longer be able to accurately query the database to determine if any data files are currently unrecoverable.

##oracle11.2.0.2开始，使用Direct-path INSERT时，如果你通过把DB_UNRECOVERABLE_SCN_TRACKING 设为FALSE来禁用定期更新控制文件机制，那么数据插入性能会得到极大的提升。但是如果这这样做了，那么你就无法通过数据库查询那些数据文件时无法恢复的了。

See Also:

Oracle Database Backup and Recovery User's Guide for more information about unrecoverable data files

The section "Determining If a Backup Is Required After Unrecoverable Operations" inOracle Data Guard Concepts and Administration

Additional Considerations for Direct-Path INSERT

The following are some additional considerations when using direct-path INSERT.

##下面列出了使用direct-path INSERT的其他注意事项：

Compressed Tables

If a table is created with the basic compression, then you must use direct-pathINSERT to compress table data as it is loaded. If a table is created with OLTP, warehouse, or archive compression, then best compression ratios are achieved with direct-pathINSERT.

See "Consider Using Table Compression" for more information.

##如果你的表是basic压缩表，那么想要插入的数据会被压缩，必须使用direct-path INSERT(此时传统路径插入的数据是不会被压缩的)。如果你的表是oltp，warehouse，archive模式的压缩表，那么direct-pathINSERT方式插入的数据压缩效率是最高的(oltp等模式的压缩表，对普通方式插入的数据也会进行压缩，但不是在插入时即进行压缩)

Index Maintenance with Direct-Path INSERT

Oracle Database performs index maintenance at the end of direct-path INSERT operations on tables (partitioned or nonpartitioned) that have indexes. This index maintenance is performed by the parallel execution servers for parallel direct-pathINSERT or by the single process for serial direct-path INSERT. You can avoid the performance impact of index maintenance by making the index unusable before theINSERT operation and then rebuilding it afterward.

See Also: