![]() ![]() Multiple files can be created by specifying multiple locations in the form directory:file in the LOCATION clause and by specifying the PARALLEL clause. One way to alleviate the problem is to create multiple files in multiple directory objects (assuming those directories are on different disks) when executing the CREATE TABLE AS SELECT statement. If there is insufficient space for all of the data, then an error is returned for the CREATE TABLE AS SELECT statement. The dump file must be on a disk big enough to hold all the data being written. This topic describes parallel loading and unloading. If DISABLED is specified, then no data is compressed for the upload operation. Choosing a compression level based on your environment, workload characteristics, and size and type of data is the only way to ensure that the exported dump file set compression level meets your performance and storage requirements. It is recommended that you run tests with the different compression levels on the data in your environment. The compression ratio generally increases from low to high, with a trade-off of potentially consuming more CPU resources. These measures vary on the size and type of inputs as well as the speed of the compression algorithms used. The performance of a compression algorithm is characterized by its CPU usage and by the compression ratio (the size of the compressed output as a percentage of the uncompressed input). This feature requires that the Oracle Advanced Compression option be enabled. To use these compression algorithms, the COMPATIBLE initialization parameter must be set to at least 12.0.0. If the name generated is not a valid file name, then an error is returned and no data is loaded or unloaded. If no extension is supplied for the file, then a default extension of. If %p or %a is not used to create unique file names for output files and an external table is being accessed in parallel, then output files may be corrupted or agents may be unable to write to the files. If the % character is followed by anything other than one of the characters in the preceding list, then an error is returned. If there is a need to have a percent sign in the file name, then this symbol substitution must be used. log was specified as the file name, then the agent would create a file named exttab_003.log. For example, if the third parallel agent is creating a file and exttab_%a. This number is padded to the left with zeros to fill three characters. The agent number is the unique number assigned to each parallel process accessing the external table. %a is replaced by the agent number of the current process. For example, if the process ID of the access driver is 12345, then exttab_%p. %p is replaced by the process ID of the current process. The symbol substitutions supported are as follows: The access driver does some symbol substitution to help make file names unique in the case of parallel loads. If you use words in identifiers that are reserved by the ORACLE_DATAPUMP access driver, then they must be enclosed in double quotation marks. Reserved Words for the ORACLE_DATAPUMP Access Driver.Restrictions When Using the ORACLE_DATAPUMP Access Driverīe aware of restrictions that apply to accessing external tables with the ORACLE_DATAPUMP access driver.Learn how to improve ORACLE_DATAPUMP access driver performance. Performance Hints When Using the ORACLE_DATAPUMP Access Driver.You can use the ORACLE_DATAPUMP access driver to unload and reload data for some of the unsupported data types The ORACLE_DATAPUMP access driver resolves many data types automatically during loads and unloads. Unloading and Loading Data with the ORACLE_DATAPUMP Access DriverĪs part of creating an external table with a SQL CREATE TABLE AS SELECT statement, the ORACLE_DATAPUMP access driver can write data to a dump file.When you create the ORACLE_DATAPUMP access driver external table, you can specify certain parameters in an access_parameters clause. ![]() To modify the default behavior of the access driver, use ORACLE_DATAPUMP access parameters. Using the ORACLE_DATAPUMP Access Driver. ![]()
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