According to http://drupal.org/node/443540:
Field storage modules could be written to store field data in a variety of ways including HyperTable, Amazon S3 or CouchDB
but I have no idea how to do
According to http://drupal.org/node/443540:
Field storage modules could be written to store field data in a variety of ways including HyperTable, Amazon S3 or CouchDB
but I have no idea how to do
Did you take a look at the Field Storage API documentation page? http://api.drupal.org/api/drupal/modules--field--field.attach.inc/group/field_storage/7
It's listing the hooks you need to implements to declare a new storage backend (hook_field_storage_info()) and to plug a field on a storage backend (hook_field_storage_OP()).