[Virtuoso-users] Transitivity query - get all transitive parent classes of a given class

[Adam S. <a.s...@gm...>]

Hello everyone,

I want to get all transitive parent classes of a given class. The data
is already stored in a Virtuoso  server with SPARQL 1.1 and the
ontology contains 1 159 021 classes.

The query that I executed is:

========================================
query 1
========================================
SELECT DISTINCT ?classuri {GRAPH <http://maze.org> {
?subclass owl:SubClassOf+ ?classuri
OPTION (TRANSITIVE , T_DISTINCT, t_in(?subclass), t_out(?classuri),
t_max(6), T_DIRECTION 1 , T_NO_CYCLES).
FILTER(?subclass = <http://maze.org/concept/4788>)
}}

but the process never ended in spite of increasing the
TN_DEFAULT_MAX_MEMORY parameter from 100MB to 5GB (after recompiling
the server again). I concluded: to many loops in the data. In fact,
there exists more than 2000 pair of classes where for each pair, each
class is a subclass from each other.

Then, a friend of mine changed a little bit the previous query. He
removed the property path "+" from the query because he is still using
SPARQL 1.0 in his Virtuoso server and he removed both t_in and t_out
parameters from "transitive option". Then, He run the following query
and it worked.

========================================
query 2
========================================

SELECT ?classuri WHERE
{ GRAPH <http://maze.org> {
  ?subclass rdfs:subClassOf ?classuri OPTION (TRANSITIVE, T_DISTINCT
,T_NO_CYCLES, T_MIN(0)).
  FILTER (?subclass = <http://maze.org/concept/4788>)
}}

========================================


My question is:

Which query is doing what is expecting? It means, to get all
transitive parent classes of a given class. Why?

Thanks in advance

Adam