Populating an XML index is parallelized, providing both inter-document and
intra-document parallelism, by using multiple pull-type parser processes
to parse respective XML documents in parallel and to call respective
`instances` of the function that generates the index entries based on
parsed XML node information. The function is configured to operate
according to a cursor-type interface model, whereby each function
instance can operate on one node at a time in a controlled pull manner
rather than in an uncontrolled streaming manner. Hence, the index load
procedure flow can be in the control of an application or routine, via
the pull parsers, rather than in the control of a serial stream-based
parser.