This section describes important differences between loading data with external tables, using the
ORACLE_LOADER access driver, as opposed to loading data with SQL*Loader conventional and direct path loads. This information does not apply to the
ORACLE_DATAPUMP access driver.
If there are multiple primary input data files with SQL*Loader loads, then a bad file and a discard file are created for each input data file. With external table loads, there is only one bad file and one discard file for all input data files. If parallel access drivers are used for the external table load, then each access driver has its own bad file and discard file.
The following are not supported with external table loads:
CONCATENATE to combine multiple physical records into a single logical record.
Loading of the following SQL*Loader data types:
GRAPHIC EXTERNAL, and
Use of the following database column types:
LONG, nested table,
REF, primary key
With SQL*Loader, if a primary data file uses a Unicode character set (UTF8 or UTF16) and it also contains a byte-order mark (BOM), then the byte-order mark is written at the beginning of the corresponding bad and discard files. With external table loads, the byte-order mark is not written at the beginning of the bad and discard files.
For fields in a data file, the settings of NLS environment variables on the client determine the default character set, date mask, and decimal separator. For fields in external tables, the database settings of the NLS parameters determine the default character set, date masks, and decimal separator.
In SQL*Loader, you can use the backslash (\) escape character to identify a single quotation mark as the enclosure character, as follows:
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '\''
In external tables, the use of the backslash escape character within a string raises an error. The workaround is to use double quotation marks to identify a single quotation mark as the enclosure character, as follows:
TERMINATED BY ',' ENCLOSED BY "'"