Oracle improvement (ancestor)

Using nuxeo 5.6 HF14 with pathOptimization in default-repository-config :
<!-- pathOptimizations after hot fix : https://jira.nuxeo.com/browse/NXP-10210 -->
<pathOptimizations enabled="true" version="2" />

The current function : FUNCTION NX_ANCESTORS(ids NX_STRING_TABLE) does a table acces full on ancestors

1st try for optimization to avoid full table scan

/* Avoid full table scan and replace with full index scan */
FUNCTION NX_ANCESTORS(ids NX_STRING_TABLE)
RETURN NX_STRING_TABLE PIPELINED IS
BEGIN
FOR r in (SELECT /*+ INDEX(ancestors) */ DISTINCT(ancestor) AS ancestor FROM ancestors WHERE hierarchy_id MEMBER OF ids) LOOP
PIPE ROW(r.ancestor);
END LOOP;
END;

Final optimization to avoid index full scan

/Replace MEMBER OF by IN (and cast) /
FUNCTION NX_ANCESTORS(ids NX_STRING_TABLE)
RETURN NX_STRING_TABLE PIPELINED IS
BEGIN
FOR r in (SELECT DISTINCT(ancestor) AS ancestor FROM ancestors WHERE hierarchy_id IN (SELECT column_value FROM TABLE(CAST(ids AS NX_STRING_TABLE)))) LOOP
PIPE ROW(r.ancestor);
END LOOP;
END;

What do you think about this ? Is it the good way ?

Documentation : http://www.oracle-developer.net/display.php?id=301

(Sorry for bad english i'm french)