| --- |
| title: Using a Custom Format |
| --- |
| |
| You specify a custom data format in the `FORMAT` clause of `CREATE EXTERNAL TABLE`. |
| |
| ``` |
| FORMAT 'CUSTOM' (formatter=format_function, key1=val1,...keyn=valn) |
| ``` |
| |
| Where the `'CUSTOM'` keyword indicates that the data has a custom format and `formatter` specifies the function to use to format the data, followed by comma-separated parameters to the formatter function. |
| |
| HAWQ provides functions for formatting fixed-width data, but you must author the formatter functions for variable-width data. The steps are as follows. |
| |
| 1. Author and compile input and output functions as a shared library. |
| 2. Specify the shared library function with `CREATE FUNCTION` in HAWQ. |
| 3. Use the `formatter` parameter of `CREATE EXTERNAL TABLE`'s `FORMAT` clause to call the function. |
| |
| - **[Importing and Exporting Fixed Width Data](../../datamgmt/load/g-importing-and-exporting-fixed-width-data.html)** |
| |
| - **[Examples - Read Fixed-Width Data](../../datamgmt/load/g-examples-read-fixed-width-data.html)** |
| |
| |
