Implements hook_field_storage_delete_field().
function field_sql_storage_field_storage_delete_field($field) {
// Mark all data associated with the field for deletion.
$field['deleted'] = 0;
$table = _field_sql_storage_tablename($field);
$revision_table = _field_sql_storage_revision_tablename($field);
db_update($table)
->fields(array(
'deleted' => 1,
))
->execute();
// Move the table to a unique name while the table contents are being deleted.
$field['deleted'] = 1;
$new_table = _field_sql_storage_tablename($field);
$revision_new_table = _field_sql_storage_revision_tablename($field);
db_rename_table($table, $new_table);
db_rename_table($revision_table, $revision_new_table);
drupal_get_schema(NULL, TRUE);
}