'Performs single delete operation on single index.
It\'s very similar to update functions (that\'s why data is in arguments)
:param index: index to perform operation
:param data: not important (because of update operations)
:param doc_id: document id
:param old_data: current data in database'

def _single_delete_index(self, index, data, doc_id, old_data):

    index_data = index.make_key_value(old_data)
    if (not index_data):
        return
    (key, value) = index_data
    try:
        index.delete(doc_id, key)
    except TryReindexException:
        return
