Describes how to set a custom datatype for a Participants Database field form element

pdb-set-decimal-datatype.php

<?php
/**
 * @wordpress-plugin
 * Plugin Name: Set Decimal Datatype
 * Description: set a custom datatype for a Participants Database decimal form element
 */
add_filter( 'pdb-form_element_datatype', 'xnau_set_decimal_type', 10, 2 );
/**
 * sets the datatype for decimal fields
 *
 * @param string  $datatype the default datatype
 * @param string  $form_element the form element type
 * @return  string  the datatype to use for this form element
 */
function xnau_set_decimal_type( $datatype, $form_element )
{
  if ( $form_element === 'decimal' ) {
    $datatype = 'decimal(14,8)'; // change this to the decimal configuration you need
  }
  return $datatype;
}

After you install and activate this plugin, you must save some change to your decimal field definition (on the Manage Database Fields page) so that the database is updated as well. If you create a new decimal field, it will get it's decimal format from this plugin.