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.