Original Export and Import Versus Data Pump Export and Import

If you are familiar with the original Export (exp) and Import (imp) utilities, it is important to understand that many of the concepts behind them do not apply to Data Pump Export (expdp) and Data Pump Import (impdp). In particular:

• Data Pump Export and Import operate on a group of files called a dump file set rather than on a single sequential dump file.

• Data Pump Export and Import access files on the server rather than on the client. This results in improved performance. It also means that directory objects are required when you specify file locations.

• Data Pump Export and Import use parallel execution rather than a single stream of execution, for improved performance. This means that the order of data within dump file sets is more variable.

• Data Pump Export and Import represent metadata in the dump file set as XML documents rather than as DDL commands. This provides improved flexibility for transforming the metadata at import time.

• Data Pump Export and Import are self-tuning utilities. Tuning parameters that were used in original Export and Import, such as BUFFER and RECORDLENGTH, are neither required nor supported by Data Pump Export and Import.

• At import time there is no option to perform interim commits during the restoration of a partition. This was provided by the COMMIT parameter in original Import.

• There is no option to merge extents when you re-create tables. In original Import, this was provided by the COMPRESS parameter. Instead, extents are reallocated according to storage parameters for the target table.

• Sequential media, such as tapes and pipes, are not supported.

• When you are importing data into an existing table using either APPEND or TRUNCATE, if any row violates an active constraint, the load is discontinued and no data is loaded. This is different from original Import, which logs any rows that are in violation and continues with the load.